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DOCUMENT RESUME

ED 056 858 SE 012 046

TITLE science Grade 9, Science Curriculum Materials.

INSTITUTION Rochester City School District, N.Y.

PUB DATE 70551p.

,RS PRICE MF-$0.65 HC-T,/9.74DESCRIPTORS *Curric-alum Guides; *General Science; Grade 9;

Laboratory Experiments; Laboratory Procedures;*Physical Sciences; Resource Materials; *ScienceActivities; Secondary School Science; *TeachingGuides

ABSTRACTThis curriculum guidc, is the third in a series of

general science guides modified from the New York State ExperimentalSyllabus, Science 7-8-9 to meet the needs of students whose interests

are in areas other than science. The guide is laboratory-oriented andconiZ-ains many open ended, pupil activities in five activity blocks;orientation, forces at work, the chemistry of matter, energy at work,and li\,ing with the atom. This collection of activities is intendedfor -cse by teachers as a suggested course of study, reference source,and topical outline, and is not a series of lesson plans. The fiveactivity blocks may be followed in any sequence. Introductorydiscussion presents topics and suggestions for the teacher concerningareas such as the outcomes from a science program, the basic skills

used in science, time sequence, teaching slow learners, teachingrapid learners, developing reading skills in the science program, andmultimedia instructional materials. (PR)

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SCIENCE

GRADE 9

1970

Division of Instruction

City School District

Rochester, New York

2

ACKNOWLEDGMENT

This ninth grade curriculum guide is the third in a

series of general science outlines which has been designed

to follow the State Experimental Syllabus, Science 7-8-9.

Adaptations and modifications were made from the State out-

line so that the citywide program in science at the ninth

grade level would more nearly meet the needs of an urban

school system. Emphasis throughout, is placed on teacher

flexibility in selecting, modifying and using this guide as

determined by appropriate classroom interests.

Material changes in content and sequence were suggested

by teachers and members of the Science Council during the

1967-68 nd 1968-69 shool years. These suggestions were re-

viewed and revised by Mr. Hartman Pogue of West High School and

Mr. James Nicols of Monroe High School, both experienced ninth

grade teachers. Dr. Samuel W. Bloom, director of Science,

edited and prepared the final manuscript for intolio-Pfi--,

Dr. George J. RentschAssistant Superintendentfor Instruction

Secretaries:

Miss Carol VandenBergMrs. Blanche Greenholtz

Summer - 1970

Page

kmledgment

troduction

Outcomes from a Program in Science vi

Basic Skills Used in Science

Time Sequenceviii

Teaching Science to Slow Learners xiii

Teaching Science to Rapid Learners xvi

Developing Reading Skills in theScience Program

xviii

Multimedia Instructional Materials xxi

Message to Teachersxxii

Lock 0 - Orientation0-1 to 0-35

Lock I - Forces at Work 1-1 to 1-102

lock J - The Chemistry of Matter T-1 to J-151

lock K - Energy nt Work K-1 to K-121

lock L - Living with the Atom

ppendix

Key Words

Block L..

Block T2

Block J

Block K

Block L

INTRODUCTION

These tentative curriculum materials for the ninth

grade general science program included in this curriculum

guide are an extension of the experimental syllabus in

Science 7-8-9 developed by the State Education Department

and modified through experience and use in the Rochester

schools. The general pattern followed in grades 7-8-9 is

toward biological orientation at the seventh grade, a modi-

fied earth and space science course at the eighth grade, and

a physical science emphasis at the ninth grade.

The units or blocks suggested in this curriculum guide

have been prepared to introduc^ a number of science concepts

corpi.dered essential in the development of scientific literacy

for all children. In addition, these units are designed to

lay a strong foundation for the more specialized science areas

offered at the upper grade levels.

This curriculum guide is intended solely for use by

teachers as a suggested course of study, reference source, and

a topical outline. The teacher should feel free to deviate fro-a

the guide as necessitated by the need for individual instruction

and by the interests of the class. THIS GUIDE IS NOT A SERIES

OF LESSON PLANS. The blocks may be followed in any sequence.

For supplemental information, the teacher is referred to the State

Blocks I, J, K, L and Experimental Part I.

All starred (*) items refer to enrichment materials to

be used at the discretion of the teacher. ThIs symbol (#)

denotes an activity. Although the units of measurement used

in the metric system are preferred in scientific fields, the

English system of measurement remains the more meaningful to

our pupil population. Teachers should use that system of

measurement which has the most meaning to pupils and which

relates more nearly to their everydry life. However, emphasis

should be placed increasingly on the use of the metric units

of measurement.

Since most c1asses in the high schools contain pupils

with a range of ability, varied reading skills, different

degrees of motivation and occupational expectations, the

teacher is urged to select from the many suggested activities

those that are more suitable and relevant to the particular

class. A large number of interest developing activities are

provided to implement the development of major understandings.

Considerable more activities have been provided than can be

performed during the regular school year. The teacher should

be selective...chocse the appropriate activities which will

broaden the science interests of the class and individuals

within the class.

At this point in the child's development, it may be educa-

t'3nally more defensible to enlarge a pupil's horizon than to

concentrate in narrow fields of science. A child's interest

may be more easily aroused if stress is placed on concepts which

iii

have the greatest general interest such as those concerning

machines, aircraft, space exploration, drug use, an'i consumer

application. Relating suAentific concepts to the everyday

environment and experiences of the pupil will Inake su1/4:n under-

standings more meaningful. Thus, the pupil will br.lcome Increasingly

aware of the role of scienc:e to nIs everyday world experiences.

Teaching emphases should include a considerab3e oppor-

tunity for lal.oratory experiences, individual project oppor-

tunities, and individual and small group involvement. It

is the expectation that these ninth grade students will

develop and be guided to a basic understanding of concepts

through many varied activities: independent study, class

discussions, demonstrations, and experimentation. The teaching

situation should provide for a ligh degree of flexibility in the

'<:lection of science experiences, choice of concepts to emphasize,

and the use of multimedia instructional materials.

A great deal of flexibility is given teachers in the

selection of course content from the suggested topical outline.

Although numerous science teachers consider preparation for

later science courses to be the principal or only aim of science

instruction, this is not a primary goal within the City School

District. While goals relating to preprofessional preparation

in science are appropriate for students planning to become

scientists, physicians, and engineers, only a small minority

of the total population is engaged in these professions. Well

in excess of 90 percent of adults are not engaged in occupations

iv

directly related to science. Thus, the choice of subject

content and the methodology used in the classroom should be

math_ chiefly for its contribution to the child's scientific

literacy. Literacy in science is essential for every indlvidual

who hopes to function effectively in our twentieth-cenzy

society.

Even though an individual does not plan to engage in

science or science-related occupations, he needs some basirl

understanding of scientific ideas to be able to comprehend

the phenomena and changes in the natural world in which he

lives. He needs to become aware of the chianges that science

is making in his environment, its long ranige ecological effects,

and its effect upon him as an individual. The selection of

science content at the high school level should contribute

to this general goal by providing the base upon which the

individual may become increasingly more literate.

The impact that science now exerts upon all aspects of

living is continuous and ever-increasing. At the high school

level, science instruction should be concerned primarily with

the observation and interpretation of the common phenomena of

the environment. At this level, science instruction should be

centered around those materials which seem most significant for

everyday living. Pupils should be encouraged to explore the

environment for themselves, become familiar with career oppor-

tunities in science, and every effort should be made to achieve a

familiarity with the world of science outside the classroom.

In the present age of expanding technology it is a

curious paradox that science teaching is still largely a

matter of the memorization of content, much of which is

rapidly becoming obsolete. The possibilities of experi-

mental procedures, of direct observation, and of first hand

experiences have been only partly explored.

The science teaching methods must be creative and

open-ended. Traditional approaches should be minimized

in favor of puDil-oriented activities. A comparative guide

follows:

TRADITIONALAPPROACH

INQUIRYAPPROACH

information INQUIRYtelling ASKINGreading about DOINGstructured learning OPEN ENDdemonstration EXPERIMENTATIONrigid procedure FLEXIBILITYdogmatic assertions QUESTIONING, ASSUMPTIONSfacts and principles PROCESS

The goal of an effective science program would be to pro-

vide a learning situation which facilitates some favorable form

of student behavior after instruction has been completed. The

liklihood of a student putting his knowledge to use is influenced

by his attitude for or against science. Teachers do influence pupil

attitudes toward subject matter and toward learning itself. There-

fore, an cveall objective of science teaching is the extent with

which pupils leave a class as favorably inclined toward science as

possible. If a pupil is favorably inclined toward science, he will

remember what has been taught, and will willingly learn it,ore about

science.

vi

Outcomes from a Program in Science

Outcomes that can evolve from a high school science

program include the ability to:

- ques,tion the what, the how and the why

- form independent judgment

- make careful plans for solving problems

- make careful observations

- locate and use reference materials effectively

- read science content with understanding

- develop a scientific vocabulary

- interpret accurately simple charts, tabl3s, and graphs

- communicate with exactness and precision

- follow instructions and directions

- recognize and use safety principles

- apply principles of science to new situations

- cooperate effectively with others

- live and work in one's environment

vii

BASIC SKILLS USED IN SCIENCE

One of the major objectives of any course in science is to

develop the basic skills used by working scientists. The fol-

lowing skills should be considered vital to the proper develop-

ment of a scientific attitude.

Ability to identify and define a problem

Ability to colaect data

Ability to organize data

Ability to interpret data

Ability to observe carefully

Ability to collect evidence

Ability to formulate an hypothesis

Ability to test an hypothesis

Ability to predict the effects of known causes

Ability to establish causes from known effects

Ability to generalize conclusions

Ability to devise a new experiment

Ability to develop a control for an experiment

viii

Time Sequence

The units or blocks included in this curriculum guide

have been designed for maximum flexibility by teachers in

planning the year's work. A working guide to a time sequence

might be:

Block 0 - Orientation 1 week

Block I - Forces at Work 9-10 weeks

Block J - C emistry of ittr

Block - Energy at Work

Block Z - Living With the Atom

3-11 weeks

10-11 weeks

5- 7 weeks

33-40 weeks

A. Block 0 - Orientation

The Orientation Unit (Block 0) is review material. Teachers

should review this material only to the extent of assuring a

degree of competency by pupils in understanding the scientific

approach and in the students' facility in using measuring instru-

ments. Some teachers may wish to devote time to the nature of

science at the beginning of the term; others will prefer to weave

the activities and understandings into their program throughout

the year. The section on measurement may be used when it is most

appropriate for the quantitative treatment of the content which

follows.

Although mathematics is the basic component for a real under-

standing of scientific concepts, the minimum use of mathematics is

advised at the ninth grade level. The experienced teacher will

adapt his teaching methods to include mathematical manipula-

tions when the child is ready and able to think symbolically.

With many children, the approach at the nintl-) !,-,rade level should

be qualitatively.

B. Block I - Forces at Work

Block I has been designed for approxir'Ltel 10 leeks of

instruction. Because of time limitations, n. 811 c the activities

listed can be performed. The teacher should lpropriate

activities which will broaden the interests of par' cular class.

In classes where this course may be a termina-_ ;arse in the

iphysical sciences, it is suggested that stress: p1,ed on con-

cepts and understandings which have an immediate relationship tc

the environment of the individual: automobiles, aircraft, space

exploration, machines, etc.

Approximate time intervals are suggested as a guide for the

average class:

Forces 2 weeks

Forces and work 2-3 weeks

Forces and fluids 2 weeks

Forces and motion 3 weeks

9-10 weeks

6

Block J - The Chemistry of Matter

This unit is designed to accomplish several objectives:

...to present a reasonable amount of content in

the area of chemistry which may be useful topupils in their everyday life

...to prepare students with some insights intomechanisms of chemical reactions and chemistry

in preparation for future courses in biology sid

chemistry

...to give students a first-hand experience withlaboratory apparatus and techniques

Judicious selections of content should be made to avoid

such meaningless activities as the memorization of chemical

symbols, formulas and uses of isolated compounds, and the

Dalancing of chemical equations by rote. Emphasis should be

placed on the applications of chemistry in the everyday ex-

perience of students with illustrations meaningful to the consumer.

This block has been designed for 8-11 weeks of instruction.

The approximate times given below suggests the stress to be given

for the various areas.

Introduction and Role of Chemistryin Society 2-3 weeks

Properties and changes in matter 1-2 weeks

Introduction to atomic structure 1-2 weeks

Common chemical changes 2 weeks

Common compounds and mixtures 2 weeks

8-11 weeks

xi

D. Block K -_Enfroy at Work

The topical outline included in this block permits many

interpretations. Any major topic could be t.le basis for instruc-

tion for a full year 2ourse. It is importanr, that teachers present

both the content and the appropriate activities at the level of

their pupils' competencies. Teachers should select activities

appropriate to the abilities of their pupils and to provide ample

opportunity and time for the quantitative treatment of some con-

cepts. Review the previous preparation of pupils in the area of

magnetism, sound and heat energy to avoid needless duplication of

content.

Approximate time intervals suggested as a guide for average

classes:

Electrical Energy 4 weeks

Magnetism 1 week

Light 2-3 weeks

Sound 1 week

Heat Energy 2 weeks

10-11 weeks

Block L - LIvInG with the Atom

Increased public interest in nuclear energy, radioactivit,

the atomic structure of matter has led to the development of

s unit as an important part of the science curriculum and cAle

d for students to understand the effects of nuclear transfor-

ions on society and the environment.

The unit is designed to accomplish several objectives:

...to develop and expand the pupils' naturalcuriosity about this topic

...to develop an appreciation of the presentand potential uses of radioactivity and nuclearenergy

...to foster an intelligent understanding of thedangers of radiation exposure

...to provide pupils with a basic understandingof the future role that atomic energy may playin society

Block L has been designed for approximately six weeks of

5truction with one to two weeks devoted to a survey of org:mic

?mistry. It is suggested that emphasis be placed in the class-

DM on the constructive and creative uses of radioactivity,

dioisotopes, and nuclear reactions. The depth of treatment of

is topic must vary, obviously, with the abilities, needs and

terests of the pupils. Pupils should be given the opportunity

observe as many phenomena as possible through demonstrations or

periments as long as they may be done safely

14

Teaching Science to Slow Learners

1r working with the slow learners, one must be aware that

they show a wide range of ability within a given class. Many

persons think they know a slow learner when they see one, so

thought the teachers of Edison, Churchill, Einstein and a

good many other geniuses.

It is a great injustice to assume that because

a student is slow in reading, he is necessarily slow in

everything. If such an attitude is taken, a pupil's best

talents may go unnoticed and his possibilities unrealized.

The most important factor in the success of the course

for slow learners is the teacher. No matter how soundly based

any or all of the material is, unless the teacher is prepared

to accept slow learners as fellow human beings, unless his

expectation of what they can do is realistic, unless he is

willing to try to see the world as the slow learner sees it,

unless he really wants to teach slow learners, a successful

year's science course is not likely. Slow learners are slow

about many things, but they are not slower than anyone else

in their sensitivity to the way in which the teacher feels about

them.

Behavioral goals are part of the course. True learning

is more than acquisition of knowledge. It involves change in

behavior of the learner.

xiv

Characteristics of Slow Learners andGuiding Principles for Teaching:

The slow learner has a short attention span.Make class activities and discussions brief.Divide class time into short (10 to 15 min.)

segments. Set minimum requirements that

cover essential aims.

He has a poor memory.Focus class attention on major ideas andconcepts. Relate the course to his needs

and environment. Make it meaningful to him.Be firm but fair.

He has a poor vocabulary. His reading is_ usually_twoor more years below grade level.

Do not expect him to read material beyond his

capacity. Give clear and simple explanationsof words which he is unlikely to understand.

His ability to follow directions is_poor.Think through all explanations for allassignments. Present them briefly, clearly,and as specifically as possible. Show him

or write them rather than tell him.

His study habits are disorganized.Keep homework assignments at a minimum, prefer-ably none. Plan work to be started in the class

period, finished at hom.

He has ia_zE._deap.00radenerallrrustmeni, to school life

and often has little understanding of conventionalstandards of behavior.

Do not expect overnight changes in behavior.Do not expect much success on the basis oflectures. Plan situations in which he canlearn what the standards are and why mostpeople accept them.

He has little ability to use standard reference works.Work with the most simple reference tools andgive him help and instruction on their use.There are many firms that give good freematerial.

XV

He finds great difficulty in sitting still and listeningfor a whole class period.

Make provisions for activity which will givehim an opportunity to talk to other studentsand move around for part of the period.

He has frequently experienced failure.Provide opportunities to experience success.Praise him for even minor accomplishments.Give him encouragement along the way.Have him win.

He does not grasp general and abstract ideas.Relate work to first hand experiences.. Be

specific and concrete. Help him make specificapplications.

He can learn.Don't expect him to learn rapidly. Knowhis mental and achievement levels. Keepthe assignments at his mental level.Repetition is important.

He has the same fundamental needs and emotions as thebright pup11.

Because he frequently has less satisfactionin having his needs met, strive to give himaffection, praise, a sense of belonging, andto re-establish confidence in himself. Create

an atmosphere of warmth and acceptance. Taketime to discuss problems even if they are notpart of the science curriculum.

xvi

Teaching Science To Ra id Learners

The nature of the academically able student provides

some guide lines which apply to his education. He learns

rapidly, has varied interests, and is adventuresome.

The academically able student needs to be encouraged

to work with science materials and to acquire competency in

laboratory techniques and methods. The student should be

encouraged to work independently while under the guidance

of the teacher.

The introduction of the quantitative approach to

science should be encouraged as the able younster can

deal readily with mathematical calculations. The concept

and practice of dimensional analysis can be incorporated in

the high school science program.

Characteristics of Rapid Learners andGuiding Priaciples for Teaching:

The material_presented must meet his needs and his alreadyestablished interests.

Since he is academically able, the teachermust present materials in accordance with thislevel of ability. This does not mean that he hasinterests in every topic nor that all able studentshave the same interests.

He needs activity.Listening and watching do not provide anadequate outlet. Plan for individual dif-ferences, provide independent study dppor-tunities and extensive laboratory experiences.

The teacher must assess each student.The teacher must learn the specific skills,facts, attitudes, and understandings each onehas or does not have.

xvii

He needs to have a knowlede of his progress and results.

Help the pupil achieve a sense of successand confidence by providing a clear-cutknowledge of his sLccess or failure.

The academically able student has a ooint ofsaturation.

Saturation may happen when the teacher attemptsto teach the subject too long, in too great adepth, or with relatively meaningless rote

activities.

HE needs competition.Competition operates as one of the outstandingincentives in his school learning.

Creativity.The rapid learner is generally creative, inno-vative, and learns to do things in an unorthodoxmanner. However, the teacher cannot assume that

the t-r.ight child will develop creativity on his

own. He needs guidance and support.

Too frequently teachers reward memory workand divergence is discouraged. Teachersshould avoid requiring meaningless tasks,over-repetition, too much drill and lookingsimply for rote memorization. Creativechildren do not function well in such an

atmosphere.

Motivation is not a bag of tricks which the teacheruses to produce leALEILaE.

Motivation depends on such factors as thechild's purpose or intent to learn, his self-concept and self-confidence, his levels ofaspiration, and his knowledge and appraisal ofhow well he is doing in relation to his goals.

Class atmosphere.Class atmosphere and democratic leadership ofthe teacher will go a long way to accomplishinggoals with superior students. Inflexiblesclhedules, threats or autocratic control cuts offcommunication of pupils with each other and the

teacher.

13

xviii

DEVELOPING READING SKILLS IN THE SCIENCE PROGRAM

Teachers cannot assume that children entering a ninth

grade science class are reading at the ninth grade level of com-

prehension. The facts are different. In an average ninth grade

classroom, teachers will find a reading range from the fourth

grade level to eleventh or higher levels. Moreover, readings

and reading skills in the sciences are unique to the subject and

pupils must be taught how to read the science text, how to follow

instructions, how to study science. Science has a special, techni-

cal vocabulary which must be understood before the science con-

cepts can be comprehended.

Many of the problems of reading science materials are

common problems in all the content fields. These problems appear

exaggerated in science due to the specialized science vocabulary.

If a teacher is to be successful teaching the concepts in science,

she must also be a reading teacher and teach pupils how to ap-

proach readings in science. Five steps should be considered

in the basal, science reading lesson:

a. developing reading readiness

b. the initial reading of the material

c. developing word recognition skills

d. discussion and rereading

e. follow-up activities

xix

Ways of Meetin Problems in Readin Science Material

a. Difficulties of Vocabulary

In order to develop the concepts of science through

the use of language, the learner must use the exactlanguage of science and relate it to his own exper-ience and his reading.

A science book contains a considerable vocabulary

of scientific words in addition to the basal vocabu-lary and these words must be taught and understood. It

is important that the teacher anticipate vocabularydifficulties at any level.

Most science textbooks have some means of calling the

attention of the pupil to a technical word when

it is first introduced: bold-face or italicized type.The teacher's job is to convince students that theycannot consider the reading completed until they have

mastered the spelling, pronunciation, and the meaning

of the terms. Students must stop, look at the word,

vocalize it, read the definition, read and reread ituntil they are able to assign a definite meaning to it

in their minds.

Probably the single most significant aid to students

in mastering vocabulary is the precept and exampleof the teacher in the 'e of terms. Scientific terms

are rigorously defined and teachers should be precise

in their use of such terms.

b. Difficulties of Conctepts

Explanation of scientific experiments that can be observed

by the pupil is often difficult. Some students accept

what they observe without trying to understand the

explanation. Others will try to understand but need

help, while still others will perform experiments and

will read and understand the explanation without help.

Each of these groups need a different means of instruction.Diagrams, similes and every aid possible should be used

to make clear those concepts that cannot be made clear

by experiments. Guided discussions often aid in clari-

fying concepts.

I 1

XX

c. Difficulties Due to Following Reading Related to Diagrams

Many diagrams are found in science material. In orderto understand the discussion the diagram must be read.Some pupils find reading diagrams difficult becausethey do not connect the discussion of a diagram to thediagram itself. The teacher can often help the studentwho is in difficulty by showing him that pictured inthe diagram is a fact that has come within his experi-ence. She will need to give direct teaching in readingdiagrams, beginning with very simple concrete illustra-tions and proceeding to more abstract generalized ones.The pupil may try to express some of his experimentsin the form of a diagram.

d. Difficulties Due to Need to Follow Directions

In science many experiments are performed which makeit necessary for the student to read to follow directions.These directions should be read slowly and thoughtfullyso that the experiment may be followed step by step inthe proper order. Specific training will need to begiven. As the student reads directions and does experi-ments, the teacher can detect any difficulty he may behaving and give him added instruction.

e. Difficulties in Seeing Relationships and FormulatingGeneralizations

Seeing relationships and forming generalizations maybe difficult for some pupils. They will need manyopportunities to consider relationships and reachconclusions or generalizations.

The rate of reading science materials will need to beslower than the rate at which children read stories in

other content areas. It is important to help studentsadjust their rate of reqding to the purpose at hand.

f. Difficulties in Differentiating Facts from Opinions

Students' reading experiences in science should be guidedtoward developing abilities to differentiate between factand opinion in their reading, to recognize the differencebetween books written for entertainment and those whichare sources of accurate science information, to learn theimportance of copyright dates and authors in determiningwhether reading materials are authentic or not, to ques-tion the accuracy of what appears in print, and to checkconflicting statements with other reliable sources.

Skill in reading science materials will need to be de-veloped. Teachers have the responsibility of teachingpupils to read science materials, meaningfully.

x xi

Multimedla Instructional Materials

Finding a suitable textbook for ninth grade science

is a difficult task. The reading levels of most general science

textbooks together with the excessive technical vocabularies

are beyond the range of most ninth grade students except the

more able. There is no one textbook currently available that

combines the concepts to be learned at a reading level that can be

easily comprehended. Moreover, teachers will find that it is

unlikely that any single textbook follows th :ity or the state

course outline. Teachers should plan, therefe, to ue multiple

textbooks written for differen l'eading leve_

single concept films, tapes, and other instr

developing their day-to-day series of activiL

Appropriate multimedia materials are available from the

Educational Communications Department. A film catalog listing

current films is available in each school. A special listing of

science films is prepared for each science teacher early in the

school year. Be certain to obtain your copy. New science films

are continually being added to the film library. As new films

are received, schools are notified. Similarly, special programed

learning materials are available for individual pupil use. A

list of such materials may be obtained from the Programed Learning

Office, 410 Alexander Street.

Many other types of ins ructional aids are available to

assist teachers to enrich and improve their instructional programs.

Plan a visit early in the school year to the Preview Center at

410 Alexander Street to examine the latest materials available for

teacher use.

film, filmstrips,

onal me...,tia in

2-3

xxii

Messalgf to Teachers

This ninth grade general science curriculum guide has

been revised in terms of classroom needs. The content emphasis

in the regular State Education Department program in ninth grade

general science is toward the science oriented student. It does

not effectively meet the needs of students whose goals, interests

and objectives are in areas other than science. For such pupils,

a modification of the State program is necessary.

It is desirable and quite essential that the non science

major bs familiar with the basic concepts and understandings

inherent in the physical sciences at a level which he can zom-

prehend. All students, as individuals and as members of

society, should have functional knowledge of their immediate

environment in terms of fundamental basic science principles.

These principles and understandings should be related to the

pupil's needs, interests, activities, daily experiences, degree

of sophistication, and future occupational objectives.

Flexibility of Prozramiu

As a teacher, you have latitude and flexibility in develop-

ing your program in ninth grade general science. This printed

course of study should be considered only as a guide; it is not

a series of lesson plans. It is the expectation of the curri

culum committee that the basic concepts and understandings listed

will be covered through the year. Many more activities and

concepts have been listed than can possibly be covered during the

year. Feel free to change, delete or modify the pupils' experiences

and activities listed in this guide as determined by the class or by

individual students.

Laboratory Orientation

This is a laboratory oriented program. Plan to provide

as many different student activities as possible within the

time period. Teacher demonstrations should be kept tc a minimum

with indivf.dual pupils or small groups performing the exercises

for the larger grou , The science classroom anc. laboratory should

be considered a won:shop area with many different types of activi-

ties taking place. If possible, student stations shoul(._ be ma-';r,,,

available for individual proje:T won:.

The units _nd laboratory sugrestions contained in this

science guide are designed on a five time a week basis for an

entire school year.

Mathematical Computations

Mathematical computations should be kept at a minimum

and used only as a tool to develop understandings. When mathe-

matical manipulations are needed, teach the class the fundamentals.

Do not assume that every class member can manipulate numbers or

relate to arithmetical concepts. Avoid any manipulations more

complex than a simple ratio, two or three number multiplication

or division, solving for one unknown, and the construction of

graphs along the positive x-y quadrant.

xxiv

PAe-ancy

Illustrath:1.3, sample activities, laboratnr7

xperiences, classroom discussions, should be related closely

to the everyday activities, interests and environrient of the

individual. Draw science analogies, examples and illustratior

from the immediate neighborhood of the school and the home.

nupils interested in their immediate environment to which they

2an relate through knowledge and familiarity. Teachers should

not hesitate to alter the prepared lesson of the if the

interests of the class indicate a change of emphasis.

26

BLOCK 0

THE NATURE OF SCIENCE,

TOOLS, AND MEASUREMENT

27

The

0-2

ORIENTATION

,.. of Science, Tools, and Measurement

REFERENCE OUTLIN_ MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

I. Science as a Dd

A. Question

1. defin- Dblem

B. Explore

1. reasa.:._ _Lor gath-ering

2. reasons for analyz-ing datF

3. suggesr, -possiblesoluticils

14. select a reasonable

solution

C. Experiment

1. according to plan

a. st--_,Te hypothesisb. li material

rel.Liredc. ou7=ine procedure

(1) defin,:controls

Important T0.onsidere7:

defineiriables

Note to teacher: This OrentationUntt may serve either as an intro-ductory unit;or the concepts andskills introduced when approprtatethroughout the school year.

A control is a clearly definedstandard by which one cancompare or measure an experi-mental object, condition orprocess with a known andunaltered reference.

Tts are indicated by the v'!.lbol Mr9terials

. ,r1 enrichment nature are 1.ndicated by an

MATERIALS

jar withscrew top

thermometerscardsrubber bandspitcherice watercandleoptical illusions

KEY WORDS

analyzecontroldatadefinehypothesisproceduresolutionvariable

0-3

ACTIVITIES

#Set up a "heat trap" as shown in thediagram to illustrate the principle of thegreenhouse, cold frame, or solar house. The

shorter infrared radiation from the sunlightpasses through the glass and heats up thematerial inside. The longer heat waves that

are reradiated cannot get out through theglass, hence the temperature rises.

\ sunny window 1."1:..\\

\

IA

(1)

\ \

\ \ \N \, N \\

N-Ii...1 . I, , \ ''

, ,1

1

,;, ........

Cords i-o shade i

1-nermorneters ,..1c:

#Given a pitcher of ice water. Note theappearance of drops of water on the outside of

the pitcher.

(1) List those facts which you think are relatedto the observed phenomena.

(2) Theorize as to whether the moisture on thepitcher comes from the water inside or fromthe air outside.

(3) Substantiate your theory by gathering morefacts.

#Light a candle. Give a minute or so for

observation. ,Extinguish. Write observations.Differentiate between observation and conclusionswhich may be drawn. Fallacy of basing observations

on prior experience.

23

0-14

REFEFNCE OUTLINE MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

d. perform experi-ment; recordobservations

e. take measure-ments(1) offset illu-

sions(2) diminish

biased obser-vations

(3) insureaccurateconclusionsor generali-zations

f. relate observa-tions

g. draw conclusions(tentative)

h. repeat procedure Scientists repeat experiments todetermine the accuracy andreliability of the originalobservations.

(1) danger of asingle test

(2) danger in generalizing

D. Conclusion(s)

1. correlate evidence

2. summarize observa-tions

3 relate to hypothesis

MATERIALS

cardboardbeakerswaterthermometer

KEY WORDS

biasedconclusioncorrelategeneralizationillusionobservationsummarizetentative

0-5

ACTIVITIES

In both top figures in the diagram the topand bottom lines are all equal. Both lines areof equal length in the bottom figures.

Pupils will find it interesting to redrawthese figures in their notebooks. Lines onwhich the illusions are based should be measuredvery carefully to make sure that they are reallyequal in length.

> < >#Cut out a piece of cardboard about two

inches square. On one side draw a bird cage.On the other side draw a bird and color it redor some other bright color. Slit the eraser ofa pencil with a knife, insert the card and lock

it in position with a short p:n. Rotate thepencil rapidly between the palms of the hand andthe bird will appear inside the cage.

When we look at something the image persistson the retina of the eye for a fraction of a

second. If the light from two objects enters the

eye in rapid succession they appear to be super-imposed because of this persistence of vision.

Moving pictures are projected at the rateof 24 frames per second. The rapid successionof images creates the illusion of smooth motionbecause of the persistence of vision. Much the

same thing happens when we watch television.

#Feel the water in a glass to determine its

temperature. Guess its warmth. Compare with theestimate of your classmates, then test with athermometer.

Place one hand in a beaker of fairly hot

water. Keep it there. Place the other hand ina beaker of lukewarm water. How would you des-cribe yor sensation of heat and cold?

REFERENCE OUTLINE

E. Application(s)

1. develop relation-ships

2. determine exten-sions and limita-tions

F. Communication(s)

1. share discoveries

2. encourage addi-tional investiga-tion

3. substantiateresults

II. Provision for universalreferences; standards formeasurement

A. Numbers and units

0-6

MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

Scientists try to apply theirconclusions to other situationsinvolving similar problems.

Scientists share data, discover-ies, and theories in order toencourage others to furtherinvestigate and verify or dis-prove their work.

Note: Whenever possible emphasizethe MKS system, not CGS.

Scientific instruments provideuniversal methods to observe and/ormeasure angles and direction,length and distance, weight,capacity, rate and time, temper-ature, pressure and various kinds

of energy.

All measurements have two distinctparts; a number and a unit ofreference. The unit tells what isto be counted; the number tellshow many units are contained inthe subject being measured. Many"units" originated in relation tothe human body; thus early stan-dards influenced the developmentof present standards.

Early Egyptians defined the cubitas the distance from the point ofthe elbow to the tip of the middlefinger of the outstretched hand.

0-7

AATERIALS ACTIVITIES

Develop a workable experiment/demonst_tion outline with students. It shouldinclude a standardized heading with the otherpertinent information as outlined by thebasic scientific method.

KEY WORDS

applicationcommunicationextensionsinvestigationlimitationsrelationshipstandardsubstantiateuniversal

One suggestion might be:

Name Experiment/Demonstration*

Class Period

Problems/Hypothesis:

Materials:

Procedure: Observation:

(Note: It is suggested that each observationfollow the procedure step it accompanies.Observations where made are to be numberedwith the same number as the particularprocedure step. e.g.;

1.2.3.

ConclusfLons(s):

1.2.

3.

Application(s):

*(Fold in center of paper)

Tpractica:_ applications wherever necessary.The "wlay" of it all.)

REFERENCE OUTLINE

B. Fundamentalquantities

1. length; dis-tance

a. definition

b. metric units

0-8


This was standardized in about4000 B.C. at what is now 46.3 cms.

Span - distance between tip ofthumb and little finger of theoutstretched hand.

Palm - the breadth of fouxfingers.

Nail - distance between thelast two joints of the middlefinger.

Digit - the breadth of themiddle finger measured at themiddle.

. Foot - the length of a foot.

. Fathom - distance betweenoutstretched arms.

The primary of fundamental dimen-sions are length, mass and time.

The metric system (France 1790)is a decimal system in whichlarger or smaller units are ex-pressed by moving the decimalpoint the proper number of placeswhen multiplying or dividing byten or a multiple of 10.

Length may be defined as thedistance between two definedpoints.

The standard of length in themetric system is the meter.

1 meter (m.)=1ength stand1 decimeter (dm.)=0.1 meter1 centimeter (cm.)=0.01 meter1 millimeter (mm.)=0.001 meter1 kilometer (km.)=1,000 meters

34

bar

MATERIALS

rulers1 mm. grid paperpapermeter sticks

KEY WORDS

decimal systemfundamentallengthmassprimarytime

0-9

#Understanding S-bdivisions of Meter Sticks

Have each pupil make a 10 cm. ruler. Theprocedure for making the ruler should be illus-strated by the teacher, step by step, on theboard.

Each pupil should have a half sheet of1 mm. grid graph paper and a rectangular pieceof stiff paper whose dimensions are at least10 cm. x 3 cm.

Ask the pupils to outline a 10 cm. x 3 cm.rectangle on their grid graph paper. Then havethem mark off on the graph paper divisions forcentimeters, .5 centimeters and millimeters Lnorder, with different length lines for eachtype of subdivision; the lines for the centi-meters should be the longest and those for eachdifferent subdivision shorter than those forthe preceding one. The teacher shc d illus-trate this by drawing it on the board. Callattention to the relationship between thedifferent subdivisions on the ruler and di-ussthe advantages of this scale. Have the pupilscut out the ruler and pas,e it on the stiffpaper for use later in measuring.

#Measuring Distances Directly with aMeter Stick

Before the class period make a list of well-defined distances in the classroom that areeasily accessible. Avoid using distances over1 meter which would necessitate moving the meter.

The selection of common objects, of which thereare several in the room, will eliminate thepossibility of congestion as a result of severalpupils wanting to make the same measurement atthe same time. Using meter sticks and the 10 cm.rulers that the students have made, measureother distances, decide on a reasonable degreeof acCuracy for each, and make a separate list ofthe answers or answer that you would acceptas correct.

0-10

REFERENCE OUTLINE MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

MATERIALS

meter sticksmetric scalesyardsticksposter board

0-11

ACTIViTIES

Illustrations:1. The longest dimensions of the cover of

the textbook.2. The height of a chalkboard.3. The thickness of a door.4. The width of a floor board of floor tile.5. The length of an unused piece of chLlk.

6. The width of a pupil's desk.

Write the li-Lt on the board or make dupli-cate copies of the list and give each pupil a

copy. Ask the pupils to make the measuremenLband to write the answers to each item, to the

required accuracy, after the number of the item

written on the board of in the space provided on

the duplicate form. Check the answers forcorrectness and discuss further those whichpresented any difficulty.

#Comparing the Metric and English Systemsof Measurement

Obtain a meter stick, or a metric scale, anda yardstick. Have a pupil read the first 16

division lines on each scale. Note that in theEnglish system the denominator varies (1/16",1/8", 1/4", 1") while in the metricsystem, the denominator is always tenths (.1 cm.,.2 cm., .3 cm 1 6 cm.)

On a large poster board, draw a rectanglewh-pse length is more than 12 inches and labelits dimension correct to the nearest 16th of aninch. On a second poster draw a congruentrectangle, and label its dimensions in metricunits, correct to the nearest 10th of a centi-meter; i.e., millimeter. Have the pupils com-pute the perimeter and the areas of the tworectangles. Note that multiplying metric units

is frequently easier than multiplying fractions.

Have the perimeters and areas expressed intwo different units, such as square inches andsquare millimeters and square centimeters.Note that to change a unit in the metric systemit is necessary to change only the decimalpoint; in the English system, however, it isnecessary to multiply or divide fractions.

Ask pupils to r'.ontrast the difficuJty ofmeasurement and computation in the two systems.

0-12


c. instrumentsfor measur-ing

(1) meter-stick

(2) dividers(3) calipers

2. mass (and weight)

a. definitions

(1) mass

(2) weight

The use of scienbific instru-ments (including measuringdevices) helps us to accumu-late more accurate data andmakes possible more highlydeveloped and universalmethods of research.

Although the terms "mass" and"weight" are frequently used _Ln.a manner which seems to implythey are synonymous, there is afundamental difference betweenthe two.

Mass is the quantitative measureof the inertia of an object; itis independent of the varyingeffects of gravity. Mass is thequantity of matter in an object.

Weight is an expression of force;it represents the pull of gravityon the mass of an object.(Quantitatively this force (weight)is equal to the mass of the objecttimes its acceleration due togravity). The mass of an objectalways remains constant.

b. metric units The standard of mass is thekilogram.

*optional

The gram is the common measurement.

1 kilogram (kg.)=Standard mass1 gram (gm.)=0.001 kg.1 milligram (mg.)=0.000001 kg.=

0.001 gm.

43-8

0-13

MTF ACTIVITIES

booksrubber bandscardboardmar.J.lespaper clipsstring

KEY WORDS

accelerationconstantexpressionforcegravityindependentinertiainstrumentsmattermeasurequantitativesynonymousweight

#How do we measure the gravity of theearth?

Demonstrate the principle of a springbalance scale by using a rubber band for thespring and one marble as the unit of weight.Suspend the scale from the end of a rulerinserted near the top of a stack of books.Slip a strip of cardboard under the ruler sothat the end hangs down along one side of thestack of books. Assemble the rubber bandbalance as shown and adjust the position of therubber band over the ruler so that the pointeris near the strip of cardboard. Make a markon the cardboard at this point and indicateit as zero.

Calibrate the scale by dropping marblesinto the cardboard box and marking it off intoconvenient divisions. The pointer shouldreturn to zero after the scale has been cali-brated and all marbles have been removed fromthe box.

\Puler

Rubber bond

Bent- paper clip

Smallcardboardbox

Cardboard sl-rip

Marbles

#Weigh some object, such as a piece of rock,

on the rubber band scales and note its weight in

marbles. Discuss possible means of calibratingthe scale in ounces.

0 -1/4

REFERENCE MA7_-_11AL MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

MATERIALS

booksspring (slinky)cardboardmarblespaper clipsstringspring balancevarious metriccontainers

KEY WORDS

0-15

ACTIVITIES

#Eubstitute a light spring for the rubberband, such as the spring from an old window-shade roller, Recalibrate the scale, usingunits appropriate to the tension and elasticityof the spring.

#Weigh common objects found in the class-room in English and metric units. Springbalances with both scales are inexpensive tobuy or may be borrowed. Pupils should becomefamiliar with metric weight units.

#Weigh out definite amounts of severalsubstances, such as a pound of sand and apound of water. Notice that a pint of waterweighs one pound. Develop the understandingthat the weight of a body is the force ofattraction between that body and the earth.Spring balances and beam balances reallymeasure the pull of gravity. To lift a heavyobject it is necessary to exert an upward forcewhich will overcome the pull of gravity.

#Understanding the Metric Units of Weight

Ask the pupils to bring to class containersthat illustrate the use of metric units ofweight such as 8-ounce (226 gm.) food containers.

Have the pupils learn the following commonmetric units of weight:

Basic unit = 1 gram1 milligram = .001 gram 1 000 milligrams = 1 gm.1 kilogram = 1,000 grams 1,000 grams = 1 kg.

One kilogram is a little more than 2 pounds.(1 kg. = 2.2 lb.)

One pound is a little less than 500 grams.( 1 lb. = 454 gm.)

41

0-16


c. instrumentsfor measur-ing(1) scales

(2) balances

3. time

a. definition

b. units

c. instrumentsfor measuring(I) clocks,

watches2) pendulum(3) metronomes

C. Derived quantities

1. area

a. definition

42

Spring scales and spring balancesare used to determine the forcewith which the earth attracts aconstant mass (weighing).

Platform and pan balances are usedto compare masses. They are usedto determine the mass of an ,7')ject

by comparing the unknown mass withknown masses (massing).

Qualitatively, time may be des-cribed as our sense of thingshappening one after another.

The unit of time is the second.It is approximately equal to theinterval between "ticks" on aclock which makes 86,400 tic;kswhile the sun moves from its noonposition on one day to its noonposition the next day.

Area is a functi-n of two dimen-sions (L2); iz; is measured insquare centimeters or square meters.

0-17

MATERIALS ACTIVITIES

stopwatchglobechalkU.S. mapcardboarddrawingmaterials

KEY WORDS

arL.?a.

balancederivedintervalqualitativescaleunknown

#Tbe study of time can be approached in aninteresting may by showing how the ability toestimate time varies. Divide the class into two

groups and ask one group to sit quietly with their

eyes closed and to raise their hands at the end of

two minutes. Members of the other group can ob-

serve the variation in the estimates. Repeat theprocedure with the groups interchanged.

Discuss ways of estimating time, using pulserate or respiration rate and repeat the procedureafter pupils have recognized the need for usingsome rhythmic procedure such as counting seconds

by Saying "one thousand and one," "one thousandand two," etc.

#Calculate the number of degrees in a bandrepresenting an hour's difference in time (360'; 24------15°). Lay out the 24 standard time meridjanson a slate globe. Point out that these meridiansextend through the centers of the time zones.

#0n a map of the United States showing thestandard time zones locate the meridians thatdetermine the standard time used in each zone.Discuss the reasons why time zones are necessaryand why the borders are very irregular. Askpupils to give examples of radio and televisionprograms that illustrate time differences acrossthe country.

Make a diagram explaining how the time zonesshift when daylight saving time is used.

#Developing a Formula for the Area of aParallelogram

Have two congruent parallelograms cut fromcardboard and backed with #00 sandpaper for useon a flannel board. Recall that the area of aparallelogram depends upon its base and itsheight. As shown in a, draw a line perpendiculartr) its base at one end and cut off the righttriangle formed. Place the triangle along theother side of the original parallelogram to forma rectangle as shown in b. Identify the dimen-sions of the rectangle and the formula for its

0-18


0-19

ACTIVITIES

area. Develop the formula A = bh for thisparallelogram. Co3or with crayon the lineswhich are used to find the dimensions. Then,as shown in c, place the triangle in itsoriginal position to re-form the originalparallelogram. Note where the dimensions maybe measured in a parallelogram.

e.Height

Variation: Keep the upper base of the secondparallelogram and cut off the right triangleshown in (J. Continue in the same manner asshown in e and f to show that height may bemeasured in more than one place.

#Deriving a Formula for the Area of aTriangle

Collect several rectangular cards. Usescissors to cut into triangles as shown in aIn each separate figure, leave one triangleone position and place the remaining triangltriangles over it, as shown in b, so that itcompletely covered, and so that the equal sicoincide. Con..:ider what fractional part oforiginal rectangle must be contained in thetriangle. (one-half). Also consider the cliffsions (length and width) of the original rectangle and the formula for its area. (A =luDevelop a formula, A = 1/21w, for the area ctriangle. Show that the base and height oftriangle are the length and width of a corrE)onding rectangle. The more convenient forn-A = 1/2bh can then be used.

0-20


46

0-21


steel tapegraph board

KEY WORDS

To obtain obtuse triangles, prepare uhecards ahead of time by cutting them intoparallelograms of various sizes and shapes.Then cut along the longer diagonal, as shownin c, and place the top triangle so that itcompletely covers and coincides with the bottom

triangle. Relate the area of the obtuse tri-angle to the area of the parallelogram.

If the rectangles and parallelograms arebacked with #00 sandpaper, this demo-70- .-tion

can be easily and effectively perforr. .41 a

flannel board.

/

#Significant Circle Dimensions

To illustrate that the area of a circledepends on the circumference of the circle, pullout a steel tape and bend it into a circle whosecircumference is 30 cm. Hold this circle against

the graph board as shown. Estimate the area ofthe circle. Now pull out the tape and form acircle whose circumference is 60 cm. Estimatethe area of this circle. Repeat with largercircles. Discuss the effect of the variation ofthe circumference of a circle on the area of the

circle.

To illustrat that the area of a circledepends upon the radius of a circle, draw on agraph board with a compass three circles whoseradii are 5 cm., 10 cm., and 15 cm., respectively.Estimate the area of each circle by counting thenumber of square cm. enclosed in each. (if the

graph board represents squai'e inc. 2s, find the

square inches and convert to square centieters).The number of square centimeters enllos..a are78.54 sq. cm., 314.16 sq. cm. and 7n, sq. cm.

respectively.

0-22


0-23


geometric shapesof a common usablenature

metric measuringdevices

Discuss the effect of this variation of theradius on the area of the circle. When the radiusis doubled the area is multiplied by 4; that is22; when the radius is tripled, the area ismultiplied by 9; that is 32. Note that a varia-tion of a radius or diameter results in variationin two dimensions, length and width.

Problems: How many times tl-ie amount carried

by a 10 cm. diameter pipe cal> be '.3arried by the

same length of (1) 20 cm. diametr pipe? (2) 30

cm. diameter nipe?

#Appreciation of Volume Measurements in

KEY WORDS Daily Life

capacity As a class demonstration, have some pupils

irregular measure the dimensions of an object in the class-

pure number room and then have the class compute its volume.

ratioregular Discuss items in common use whose volumes

volume are important. Identify the geometric shape orcombination of shapes which are apparent in each

of the items. Tell what dimensions are neededto compute the volume of each and what instru-ment'3 or tools are needed to measure thesedimensions.

0-24


0-25


cottonleadcm. rule

KEY WORDS

ITEM SHAPESIGNIFICANTDIMENSIONS

INSTRUMENTS

Pile ofCoal

ConicalSolid

Height, dia-meter of itsbase

Meter StickSteel Tape

CementConduit

Cylin-dricalShell

Outer d-meter, erdiameter,Length

Outside calipersInside cal:ipersSteel Tape

Cup-boards

Rectang-ularPrism

Length, widthheight

Steel Tape

Refrig-erator

Rectang-ularPrism

Length, widthheight

Steel Tape

#Comparing "Weights"

a. "Weigh" out approximately 454 grams (one lb.)

of cotton and approximately 454 grams of lead.Then, using a 3entimeter rule, estimate thevolume occupied by each subStance.

How do your observations help you to knowmore about "density?"

b. Compare the "weights" of equal volumes ofcotton, lead and water.

(1) How do your observations relate to anunderstanding of the term "specific gravity?"

(2) How are density and specific gravityalike; unlike?

REFERENCE OUTLINE

2. volume (solids)

a. definition

b. metric units

0-26


Volume is a function of thl-eedimensions (L3); it is measuredin cubic units e.g., cubiccentimeters or cubic meters, anddescribes the amount of space anobject occupies.

c. instruments for The relationship between mass andmeasuring (see volume of an object is known aslength) its density. Density may be

expressed in 1bs./ft.3(Weightdensity in the English system maybe expressed in lbs./ft3). Thespecific gravity of a substance isa ratio represented by a purenumber which tells the number oftimes a substance is as heavy asan equal volume of water.

d. regular solids

e. irregular solids The volume of irregular solids may(optional) be measured indirectly. (Any

displacement demonstratior

3. capacity andliquid vo)ume

a. definition

b. metric units

c. instruments formeasuring grad-uated cylinders

* optional

Capacity is a measure of liquidor dry content.

In the metric system, the standardof volume is the liter; it is usedfor both liquid and dry measure.

0-27

MATERIALS ACTIVITTF

various liquid #Capacity of Common Liquid Containers

containersgraduate a. Have ready several different common liquidserving containers containers for individual use whose capacity should

be known drinking glasses, fruit glasses and cups.Fill each with water to the customary level andpour the contents into a graduated measure to learnthe capacity of each in milliliters. Make a listof the containers and their capacities.

KEY WORDS

b. Have ready several different serving containerswhose capacity should be known - pitchers, bowls,teapot and coffemaker. Add known quantities of

water to each container until various desiredleveTh are reached. Make e. chart listing thecapaities of the various containers measured.

c. Set up problems:

1. A 12-ounce can of frozen lemonade concen-trate mixed with three cans of water willfill a pitcher of what capacity? How many8-ounce glasses can be filled with thismixture?

2. A woman is going to serve iced tea at adinner for eight people. She plans toserve the tea in 8-ounce glasses with lcecubes that take up 2 oz. in each glass. If

she allows two glasses for each person,how many potfuls of strong tea should shemake beforehand, assuming that the teapotholds three standard measuring cups?(1 cup = 8 oz.)

Plan to serve hot cocoa to a group of 10friends after skating. If the cups hold7 oz., about how many quarts of milk shouldbe on hand? Allow for extra cups if desired.

0-28


MATERIALS

mercurywatergraduates

KEY WORDS

0-29

ACTIVITIES

#Measuring Small Quantities of a Liouid

Reading should be made at the cer.ter of thesurface of the liquid because of the ibeniscus (thecurved upper surface) caused by capillary action.The graduate should be held level and the readingshould be made at eye level. The diagram at theleft shows a liquid such as water in a gradu-te.The one at the right shows a liquid such asmercury.

40

#Understanding Metric Units of Capacity

a. Help the pupils make a list of common items

which are measured in liters, milliliters orkiloliters.

b. Have the pupils learn the following metricunits of volume which are useful in measuringsmall quantitites and which are used for bothlicluid and dry measure.

1,000 milliliters = 1 liter

1,000 liters = 1 kiloliter

1 liter = 1.06 quarts (11quid) and .91quarts (dry) or approximatelyone quart.

0-30

REFERENCE OUTLINE

4 temperature

a. definition

b. units(1) °F;°C

(Conversions)*


Temperature may be regarded as thedegree of hotness (or coldness) thata body possesses. It may bemeasured in degrees of Fahrenheitor degrees of Celsius. Thetemperature of an object depends onthe motion (average kinetic energy)of its molecules.

c. instruments for Note: Teacher option to employmeasuring-- graphs. The development of and(1) thermometer the use for predictability, etc.

(2) thermocouple

5. pressure*

a. definition

b. units(1) gm/cm2.kg/m2

c. instruments formeasuring(1) barometer(2) manometer

6. rates - speed;frequency (optional)

a. definitions

*optional 56

Pressure is the force Der unit area.

Speed has dimensions of both timeand length (distance).

Speed represents the magnitude Ofvelocity (velocity possesses bothmagnitude and direction).

Frequency may be regarded as thenumber of vibrations per second orthe number of waves that pass agiven point per second or the numberof events occurring per giveninterval of time.

MATERIALS

bi-metal stripwirebatterieslampsource of thermalenergyring standsvarious wires ofdifferent metalsgalvanometer

KEY WORDS

CelsiusdimensionenergyeventFahrenheitfrequencykineticmoleculepressureratespeedtemperaturethermocouplethermometervelocityvibrationwaves

0-31

ACTIVITIES

#The principle of the type of thermostatused to regulate room temperature can be demon-strated very easily, by means of the apparatusshown in the diagram. A bimetallic bar (unequalexpansion bar) is clamped in horizontal positionto a support. A wire attached to the bimetallicbar is placed in a circuit with dry cells and asmall lamp. The end of a wore leading from thelamp is attached to another support so that ittouches the end of the bimetallic bar. Heatingthe bar with a candle causes it to bend upwardand break the circuit. As soon as the bar cools,it bends downward again and completes the circuit.The lamp, of course, represents the motors thatdrive the furnace and circulators.

#Scrape the paint from a piece of coat

wire. Twist together one end of this wire and theend of a copper wire. Connect the opposite ends

Galvanometer

57

0-32

FERENCE OUTLINE MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

58

0-33


KEY WORDS

of these wires to a sensitive galvanometer.Heat the junction of the iron and the copperwires with a candle flame. Note the deflectionof the galvanometer needle. Try a bunsenburner flame.

This device is a simple thermocouple. The

principle illustrated is made use of in electricthermometers for measuring temperature insideengines and in other inaccessible places.

SS

0-34


b. units

c. instruments formeasuring(1) see time(2) see length

7. angles (direction;location)

a. definition

b. units (degrees,minutes, seconds)

c. instruments formeasuring-protractor(1) magnetic

compass(2) sextant(3) clinometer

*optional

A degree is a unit which isequivalent to 1/360th part ofthe circumference of a circle.

60

MATERIALS

variousthermometerscorkmagnetizedneedlewatercardboard

KEY WORDS

anglescirclecircumferencedegreeequivalentprotractorsextant

0-35

ACTIVITIES

#Understanding Scales Used in Temperature-Measuring Devices

Invite the pupils to bring to class someinstruments or sketches of scales of suchinstruments used to measure temperature. Theteacher should point out the many kinds ofthermometers, such as centigrade, Fahrenheit,clinical, candy, deep-fat, meat, oven, andcar radiator thermometers. Thermostat scaleswill vary on these instruments.

During the class period, have individualpupils explain the different scales used. They

should note the units used, the method of showingsubdividions and the upper and lower limits ofthe scale. Encourage the use of the chalkboardfor showing subdivisions. Have the pupils explainhow to decide on the value of each subdivision,why some subdivisions are not numbered and whythe upper and lower limits differ according to

the use of the thermometer.

#A compass can be made by pushing amagnetized needle through a cork and floating ithorizontally on water in a vessel made of glass,aluminum or pottery.

Flol- cork

M ag n eti zed _Waterneedle

#Show pupils how to use a watch for acompass. Point the hour hand in the directionof the sun. South will then be midway betweenthis and the figure 12 on the watch.

Set up a simple problem in dead reckoningand solve it with only a watch for an instrument.

SI

BLOCK I

FORCES AT WORK

I-1

FORCES AT WORK

Forcesdirection and amountbalanced and unbalanced forcesgravitation

Forces and Workworkenergypowermachines

Forces and FluidsdensitypressurePascal's LawArchimedes' PrincipleBernoulli's Principle

Force and MotionspeedvelocityaccelerationNewton's Laws of Motionconservation of momentum

Important conceDts are indicated by the symbol (#). Materialsconsidered of an enrichment nature are indicated by an asterick,

* )

1-2


I. Forces A force is a push or a pull.

A force is any action that pro-duces or tends to produce a changein the motion of an object.

A. Direction and Amount The effect that a force has on anobject is determined by both themagnitude of the force and thedirection of the force.

1. magnitude The magnitude is the size or amountof a force.

2. direction

B. Balanced and unbalancedforces

1. balanced

In the meter, kilogram, second (MKS)system of measurement, the magnitudeof a force is expressed in units ofnewtons.

The direction of a force is thedirection that the force tends tomove an object.

Two forces equal in magnitude andacting in the same direction areequal to one force with twice themagnitude of a single force andacting in the same direction as thetwo forces.

Two forces equal in magnitude andopposite in direction cancel eachother.

A balanced force is a force that isopposed by one or more forces sothat they cancel eaoh"other.

A balanced force cannot produce achange in motion.

MATERIALS

KEY WORDS

forcemagnitudedirectionnewtonbalanced force

I-3

ACTIVITIES

At this point teachers should introduceor review appropriate material. It is suggestedthat most pupils be given the experience of usingthe MKS system in which the meter, kilogram, andsecond are the fundamental units of length, mass,and time, respectively, and the newton is thederived unit of force. Pupils should also havesome opportunity to use the more familiar English(FPS) system in which the foot, pound, and secondare the fundamental units of length, force, and

time, respectively.

One newton is equal to 0.224 pounds or justa little less than 1/4 pound.

One pound is equal to 4.46 newtons or justa little less than 41/2 newtons.

#To become familiar with the magnitude ofa newton force in relation to the familiar lift-

ing, pushing, and pulling forces, have pupilscalculate forces such as their own weight innewtons. This is done by multiplying weight inpounds by 4.46.

There will be only insignificant errors inindicating on laboratory scales 100 grams asbeing equivalent to 1 newton and 1 pound as beingequivalent to 4.5 newtons.

#If equal and opposite forces act on a cord,it is difficult for students to understand thatthe tension in the cordis the same as eitherforce and not their sum: Clamp a pulley at eachend of the front edge of the demonstration table.Hang a 200-g. mass on the end of each of twopieces of cord, pass the cords over the ptqleysand attach them at the center with wire hooks,easily made from paper clips. After suitableairing of opinions as to the tension in the cord,disconnect the hooks and insert a spring balance.Then let the class discuss the probable readingsof two spring balances, end-to-end between thehooks, and then demonstrate this. Ask what the

The use of the MKS system is optional

I-4


2. unbalanced An unbalanced force is a force thatis not completely opposed by one ormore forces, leaving a net force toact.

An unbalanced force always producesa change in the motion of a body.

MATERIALS

KEY WORDS

unbalanced forceequilibrium

1-5

ACTIVITIES

balance reading would be if one of the masseswere replaced by a rigid connection. To try

this, attach the spring balance to a clamp

fastened at the middle of the front edge of

the table.

At this point the concept of a force asa push or a pull should be established, but

its association with motion should be minimized

until consideration of the laws of motion.Call attention briefly to various familiarforces: weight, muscular contraction, molecularforces reoulting in material strength andelasticity, and friction.

Especially, identify weight as a forceand justify the use of weight units in express-ing the magnitude of forces. Hang a weight from

a coiled spring and show that extensions of the

spring caused by other forces can be expressedin weight units since they produce the sameeffect as weights.

1-6


C. Gravitation Gravitation is a weak force ofattraction between any two objects.

1. universal nature All objects in the universeattract each other.

2. mass Mass is the amount of matter ina body.

3. distance

4. weight

The greater the mass of two bodies,the greater the gravitationalattraction between them.

The greater the separation betweentwo bodies, the smaller thegravitational attraction betweenthem.

Weight is the amount of thegravitational attraction betweena body and the earth.

68

1-7


.Gravity is a special case of gravitation,

and is the force of attraction between the earth

and an object. Gravity is the force with which

pupils are most familiar. Not all textbooks make

this distinction; the two terms are often usedinterchangeably.

KEY WORDS

gravitationgravitymassweight

It is difficult if not impossible, todemonstrate the gravitational attraction betweensmall objects with the apparatus available inmost school laboratories. In 1798, HenryCavendish used a torsion balance to measure thegravitational attraction between lead ballshaving diameters of two inches and eight inches.Compared to the force of gravity on the lead,the force of gravitational attraction betweenthe balls was in the order of magnitude of 10 -8 .

Th4 means that the first force was 100,000,000(100) times that of the second.

Teachers should introduce the use of "powersof 10" when applicable. This is a review ofmaterial studied in the mathematics courses ingrades 7 or 8.

#Disregarding relativistic effects, theamount of matter in a body (its mass) alwaysremains the same, even when the body isweightless.

Since weight is the gravitational forcebetween the earth and a body, the body's weightwill decrease with increasing distance from the

earth.

Since weight is a force, it can be completelyopposed by another force or set of forces toproduce a weightless body.

#Comparison of Masses and of Weights

The relative masses of several objects canbe determined by using a constant force toaccelerate the objects. The device shown on thefollowing page is designed to provide thisconstant force by allowing the rubber band to bestretched the same amount each time. Similardevices using a spring or rubber band aresatisfactory.

83

1-8

REFERENCE OUTLINE MAJOR UNDERSTANDINGS AND.FUNDAMENTAL CONCEPTS

1-9


Rest the apparatus on a flat table. Place

an object in the cut-out portion to stretch the

rubber band. Release the object and note itsmaximum speed and distance of travel. A variety

of objects can be used, but empty milk containerspartially filled with sand and gravel areespecially recommended. (When the same types ofcontainers are used, the effects of friction areessentially the same each time.) Objects havinggreater masses will travel slower than objectshaving less mass. Instruct the pupils to arrangethe objects in a sequence from the smallest massto the largest mass. (The same type of comparisonis theoretically possible on any planet or inspace.)

KEY WORDS

Use scales or spring balances to weigh the

objects. Line them up in order of increasingweights. Compare with the previous results.(On another planet the comparisons of the weightswould be the same, but the weights indicated onthe spring balances would differ.)

Object.DowalSiicks

Rubber band

#Mass and Weight on the Different Planets

Use the chart below to help calculate yourweight on the surface of each of the planets ofthe solar system. Multiply your present weight

by the value in the second column to find yourprobable weight on the associated planet. Columns

3 and 4 of the chart refer to a typical personhaving a mass of 50 kilograms and a weight of490 newtons (110 pounds) on Earth.

I-10


-11


KEY WORDS

Planet Multiply yourweight by

Masson Planet

Weighton Planet

Mercury .3 50 Kg 147 nt (32 lb)

Venus .9 50 Kg -441 nt (99 lb)

Earth 1.0 50 Kg 490 nt (110 lb)

Mars .33 50 Kg 182 nt (42 lb)

Jupiter 2.65 50 Kg 1300 nt (292 lb)

Saturn 1.14 50 Kg 557 nt (125 lb)

Uranus .96 50 Kg 470 nt (106 lb)

Neptune

1

1.1 50 Kg 538 rv: (121 lb)

Pluto (7) 50 Kg (?)

These tables are for reference. Pupils should not be expected

to memorize this information but should know how to use it.

#Using a Platform Balance to Determine Mass

A platform balance provides a precise andrapid means of comparing the relative masses of

two objects. Since the force of gravity is

greater on large masses than it is on smallermasses, two objects may be suspended fromopposite ends of an equal arm balance, and anydifference between the pull of gravity on eachbecomes readily apparent.

A crude balance made by using commonmaterials such as a dowel stick, string, and twoempty milk containers will give results that aresurprisingly accurate. Have the pupils make their

own balances and determine the mass of a numberof small objects, by balancing the unknownsagainst known masses.

#Metric Mass and Weight Measures

Weigh objects in both the English and themetric systems to show the relationships betweenthe mass and weight units in both systems.Express familiar masses in grams and kilogramsand weights in newtons.

1-12


1-13

MATERIALS ACTTVITIES

A search of most kitchen storage cupboardswill provide many cans and boxes whose massesare expressed in grams and whose weight isexpressed in ounces or pounds. Display examples.

Point out that one of the major merits ofthe metric system lies in the relationshipbetween its units of length and mass; one cubiccentimeter of water has a mass of one gram.

Develop the idea that the size of units isnot in itself an advantage and that one systemis not capable of greater accuracy than theother. Also stress that both systems are basedon arbitrary standards since the originalintention to base the meter on the circumferenceof the earth has never been achieved.

KEY WORDS


II. Forces and Work

A. Work

1. definition

2. measurement

Work is done whenever a force actsto move an object through a distance.

Work is measured by the product ofthe force and the displacement inthe direction of action of the force.

3 units One joule is the work done when aforce of one newton acts through adistance of one meter.

*Until the metric system is more commonly used in everydayaffairs, teachers may teach either the preferred MEE systemor the English system

,oRDS

Joule

OPtiptlal

1-15

ACTIVITIES

#Regardless of the difficulty of a task,there is no work done in the scientific senseunless a force or a force component causes adisplacement in the direction of action. Thus,no work would be done in merely holding a weightregardless of how heavy it is, whereas workwould be done lifting the smallest atomic particle.

Joule is pronounced "jool". Other units ofwork are the erg (a force of one dyne actingthrough a distance of one centimeter) and thefoot-pound ( a force of one pound acting througha distance of one foot).

It is suggested that pupils also have someexperience with problems dealing with the foot-pound. However, the dyne and erg should not tediscussed at this level.

Whenever an object does work, it losesenergy. Conversely, when work is done on anobject, it gains energy.

*Work and energy are scalar quantities sincethey are independent of direction. The basicunits for energy and work are the joule, the erg,and the foot-pound. In addition to these units,the electron volt is a useful energy unit foratomic phenomena and is equal to 1.602 x 10-19joule.

#Comparing Amounts of Work

Place a box on a table. Assume that thetable top is 1 meter above the floor and the boxis 1/4 meter high. Make several piles of booksor notebooks with each pile weighing a newtoneach. Place them on the floor at the base of thetable. Remind the pupils that a joule of work isperformed when a newton of force is exerted overa distance of a meter. Have the pupils performvarious amounts of work such a 2, 2.5, and 5.75joules by lifting one or more piles from thefloor to the table or to the top of the box.

77

REFERENCE OUTLINE

73

1-16


1-17

4ATERIALS ACTIVITIES

* Point out that most of the pupils' exertion islifting their own weight as they bend and standerect, rather than the relatively small amountsof work that are done in lifting the light books.Continue this activity until the pupils havedeveloped a secure feeling for the relativevalues of the newton force and the joule of work.

After pupils have computed the work involvedin lifting an object weighing 2 newtons to a heightof one meter, challenge them to compute the work .done in carrying it a horizontal distance of 10meters from the point one meter above the ground.The answer is not 20 joules since the 2-newtonforce is not in the direction of motion. Actuallythe work is negligible but there is insufficientinformation to solve the problem.

EY WORDS

*optional

1-18


B. Energy Energy is the ability to do work.

1. potential energy Potential energy is the energypossessed by an object because ofits position or condition.

Potential energy is equal to thequantity of work that was performedto bring it to that position orcondition.

By restoring an object to itsoriginal position, potential energyis transformed into kinetic energyand work is done.

2. kinetic energy Kinetic energy is the energy anobject has because it is moving.

80

1-19


#Energy and the Piledriver

KEY WORDS

energypotential energykinetic energy

Potential energy and the work done by afalling object can be shown with a simple device.Drive a nail into a piece of soft wood byallowing a weight to fall on it. Guide thecylindrical steel or brass weight by a largediameter glass tube, or a cardboard mailingtube 1/2 or 1 meter long. Start the nailstraight with a hammer. Measure the originalheight of the nail and its height after a blowfrom the falling weight. From the originalheight of the driver and its weight, compute itspotential energy. Using these figures, calculatethe average force with which the nail resistsbeing driven (weight of object x heightfallen = average force x distance nail moves).

In the discussion, point out that thisresistance is the force necessary to deceleratethe falling weight in a short distance in whichit is stopped.

#Work Done by a Falling Object

Drive a finishing nail halfway into eachend of a short wooden dowel. Attach a paperpinwheel to one of the nails with masking tapeand suspend the apparatus so that the dowelrotates freely. Tape one end of a string to thestick and attach a weight to the bottom of thestring. Demonstrate that work is done on theapparatus by rotating the stick with the fingersuntil the string is fully wound. At this point,the work done has increased the potential energyof the weight. Releasing the weight rotates thepinwheel and the original work is recovered.

gi

1-20


MATERIALS

KEY WORDS

1-21

ACTIVITIES

Show that more work can be stored and recoveredas heavier weights are substituted in thisdemonstration. Point out that some of the work

done was used to overcome friction and cannotbe recovered easily.

#Effects of Mass and Velocity on Kinetic Energy

Place a string through an empty thread spooland stretch the string across the classroom.Strike the spool with a rubber stopper on a dowelstick to propel the rider along the string. Show

that the greater the mass of the rubber stopperand/or the greater its velocity as it hits thespool, the greater will be the kinetic energyapplied.

1-22


3. conservationof energy

Energy is neither created nordestroyed during the process oftransformation from one form toanother.

Recall, however, that there is anequivalency between mass and energyaccording to Einstein's equation:

E = mc2

1-23


#Conservation of Energy--Galileo's Experiment

KEY WORDS

conservationof energy

Hang a pendulum from a clamp attached to avertical support rod, and behind it mount a meterstick which is perfectly hortizontal. A tightly-stretched horizontal string can be used insteadof the meter stick. Show that if a pendulum is

started on one side at the level of the meterstick, it will swing as high cn the other side,ignoring friction losses. Discuss the changefrom potential, to kinetic, and back to potentialenergy, making clear their equivalence.

Clamp a horizontal rod B to the pendulumsupport A, so that it will project and interrupt,the motion of the pendulum to make it swing inan arc of smaller radius. If started at thelevel of the meter stick, the bob will swing tothe same height.

Ask the pupils to predict the height of thisrod when it will force the pendulum to loop

around it. Demonstrate this.

#Potential and Kinetic Energy

The "cum-bak" is an interesting child's toywhich can be used to illustrate energy concepts.It consists of a cardboard cylinder containing arubber band stretched between its ends and alongits axis. From the center of the rubber band hangs

a weight. When the cylinder is rolled, the weightwinds up the rubber band and when the initialkinetic energy has been used, the rubber bandunwinds, making the toy come back. When wound up,

85

I-724


C. Power Power is the time rate at whichwork is done.

*Two units of power are the wattand the joule per second.

*One watt equals one joule persecond.

*optional

1-25


KEY WORDS

powerwatt

it will roll up an incline. If slightly wound,and started down an incline, it will graduallyslow down to a stop and may reverse itself.

Compare its behavior with that of anidentical cylinder in which the weight andrubber band have been replaced by an equalweight of lead shot held in place against oneend by paraffin.

A simple pendulum, or a weight bobbing upand down on the end of a coiled spring can beused as a device in which energy is repeatedlytransformed. Ask where the energy is entirelypotential, entirely kinetic, and a combinationof the two types. Have pupils explain why themotion eventually ceases.

A double incline can be made of strips ofglass and a cylindrical weight allowed to rollback and forth. Glass strips up to 30 centi-meters in length and several centimeters wideare often available from glaziers as discards.The slope of the inclines should be very gentle,perhaps 1 in 50. The period of such anarrangement is long enough to permit identifi-cation of the various energy states as they occur.

#0ther units of power are the kilowatt, thefoot-pound per second, and the horsepower. Onekilowatt equals 1000 joules per second. Onehorsepower equals 746 watts (or 550 foot-poundsper second).

Although the horsepower is well establishedas a power unit in the English system of units,introduction of the watt as a mechanical unit ofpower is gaining in popularity because it providesan immediate conversion between mechanical powerand electrical power.

1-26


NAT0IA

10).1911k

1-27

ACTIVITIES

b Humans

Pupils May measure the power they candevelop in rUnning upstairs. The work done isthe ploduct Of the student's weight, the numberof steps and the height of the risers. Theteacher should make sure that pupils doing thisare in good health before allowing the trial.

Point °Tat tnat such a large power (in manycases more than one horsepower) can only bedeveloped by a human being for brief and

infrequent Periods. Suggest that the same testattempted on the stairs of the Empire Stateguildln, or of some tall local building ormonument, "Uld prove this conclusively.

Rave 12011Dils calculate their power in wattsDY.mUltiplYIng their weight in newtons by the

height of the stairs in meters, and then dividing

the Dboduct by the time in seconds. Each 746watts is equ Ivalent to 1 horsepower.

#measurin the Power Develo ed b an

tieing simple Prony brake to measure thepower tbat developed bY an electric motor isa good culmIriating activity for reviewing tl-aconcepts of torce, work, and power in a practicalindustrial application. This activity isprobably best performed as a demonstration withtne j1S performin g the computations. It isdesizbable to have a revolution counter which mayDe available in the Physics laboratory.

force. Apply a frictional forceto an-aIectriZ-iotor by suspending two scales(calibrated in newtons) from a horizontal supportand connecting rope between the scales and themotol, nu1leY as shown in diagram below. Adjustthe tercsion of the rope so that there is anoticeaDle difference in scale readings when themotol, is o Pel'ating- This difference in readingsis caused by friction between the rope and thepulley.

REFERENCE OUTLINE

1-2 8

MAJOR UNDERSTANDINGS AND.

FUNDAMENTAL CONCEPTS

1-29


Work. Permit the motor to perform aquantity of work by applying the frictionalforce while the pulley rim travels a measur-able distance. This distance is determined bymultiplying the circumference of the pulley bythe number of revolutions that it makes duringthe trial period. One way for pupils tomeasure the circumference is by cutting a lengthof string to fit around the pulley and thenstretching the string out against a meter stick.Because the motor will probably be turning toofast to count revolutions, it is suggested thata small revolution counter by used. The work(in joules) = force (in newtons) x distance(in meters).

Power. Use a stop watch (or a watch witha sweep second hand) to time the period duringwhich the motor is performing the measuredquantity of work.

KEY WORDS

The power (in watts) = work (in joules)divided by the time (in seconds). Because themotor is not 100% efficient, the mechanicalpower, measured by the prony brake method, willbe somewhat less than the electrical power whichis consumed in operating the motor.

1-30


D. Machines inGeneral

Machines are devices which trans-- form work into a more useful formby changing the speed, direction,distance, and/or the amount of aforce.

1. effort Effort is the force that isapplied to a machine.

2. resistance

3. work input

4. work output

5. the law ofmachines

6. uses of machines

Resistance is the force which amachine can overcome with a giveneffort.

The work input of any machlt isthe product of the effort and thedistance through which this forceacts.

The work output of any machine isthe product of the resistance andthe distance through which thisforce acts.

If there were no friction, theamount of work that is put intoa machine (work input) would beequal to the amount of work thatthe machine accomplishes (workoutput).

Some machines increase the amount ofa force by decreasing the speed anddistance through which the forceacts.

Some machines increase the speed anddistance through which a force actsby decreasing the amount of a force.

Some machines change the directionof a force.

7. the mechanical The mechanical advantage of anyadvantage of a machine is the number of times thatmachine it will multiply the effort.

92

1-31


#In discussing this area teachers should usethe law of machines to stimulate thinking. Thisequation is: -effort x effort distance = resistancex resistance distance. It can be shown that ifthe effort is smaller than the resistance, thenthe effort distance is larger than the resistancedistance.

Mechanical advantages are ratios and there-fore are never accompanied by a scientific unitof measurement. Thus, a mechanical advantageof "5" would indicate that the effort is multi-plied five times by the machine and a mechanicaladvantage of 1/5 would indicate that the effort isbeing reduced by a factor of 5. A fractionalmechanical advantage is useful in situations whereit is desired to sacrifice force to gain increaseddistance or increased speed. A mechanicaladvantage of 1 is not useful in multiplying force,speed, or distance, but can be helpful inchanging direction. For example, it is easierfor people to push downward than upward.

KEY WORDS

machineeffortresistancework inputwork outputmechanicaladvantage

1-32


E. Simple Machines

1. lever

a. mechanicaladvantage

b. work output

All simple machines are variationsof the lever and the inclinedplane.

Simple machines include the lever,wheel and axle, pulley, inclinedplane, wedge, and screw.

Complex machines are made of twoor more simple machines.

The lever is_a rigid bar which isrotated about a pivot (pivotalpoint) called a fulcrum.

The effort arm is the perpendiculardistance from the fulcrum to pointwhere the effort is applied atright angles to the lever.

The resistance arm is the perpendi-cular distance from the fulcrum tothe point where the resistance isapplied at right angles to the lever.

The mechanical advantage of a leveris the ratio of the length of theeffort arm to the length of theresistance arm.

The work output is the product ofthe resistance and the resistancearm.

c. work input The work input is the product ofthe effort and the effort arm.

*Review only ...pupils have been exposed to a study of simple

machines in their elementary science program.

94

MATERIALS

KEY WORDS

simple machineleverwheel and axlepulleyinclined planewedgescrewfulcrumeffort armresistance arm

1-33

ACTIVITIES

Machines of the lever type utilize the prin-ciple of the turning effect produced by a forceabout a pivotal point. The torque, or turningeffect, is the product of the perpendicularforce and the pivotal arm length. Thus, manycombinations of forces and pivotal arm lengthscan be multiplied together to obtain a givenproduct. The machine is the mechanism whichchanges the relative values of force and distanceto those desired.

Machines of the inclined plane type resolvea force into two or more components. The effortis applied to overcome one of these componentsand thus move the resistance in the generaldirection that is desired by along a path thatis usually longer than that which would benecessary without the machine.

Teachers may wish to refer to Block B, TheBody in Action, pp. 6-13 for resource materialon forces, levers, and work. If this topic hasbeen previously studied in Block B, it should bereviewed briefly. If the topic has not beenpreviously taught, include examples of the partsof the human body which serve as levers.

Pupils should be given the opportunity towork with levers to discover the various relation-ships. Most pupils should discover that, when alever is in equilibrium, the torque which tendsto produce motion in one direction is essentiallyequal to the torque which tends to produce motionin the opposite direction. The computed torquesare usually not equal because the weight of thelever has been disregarded.

#Levers may be found operating in manydevices which are in daily use. Have pupilsdetermine the location of the fulcrum and thepoints of application of the resistance and effort.Some of these devices are shown in the followingdiagrams.

I-34


1-35


KEY WORDS

#First Class Lever

Tie a strong rope around a heavy object suchas a box filled with rocks or sand. Challengethe pupils to lift the object from the floor bypulling upwards on tha free end of the rope usingonly one hand that is fully extended. CAUTION:Place padding at the fulcrum to avoid marring thedesk. Use a long rigid stick Csuch as a windowpole) set up as a first class lever tc demonstratethe advantages of this simple machine. Permit thepupils to calculate the mechanical advantage bydividing the length of the effort arm by the lengthof the resistance arm and then check their results

1-36


1-37


by comparing the distance that the resistance israised when the effort moves 10 centimetersdownward.

KEY WORDS

1-38


2. inclined plane

a. mechanicaladvantage

An inclined plane is a flat surfacethat. is slanted so that one end ishigher than the other.

The distance along the slant betweenthe ends is called the length of theplane.

The difference in elevation betweenthe ends is called the height of theplane.

The mechanical advantage of aninclined Plane is the ratio of thelength of the plane to its height.

b. work The work output is the product ofoutput the resistance and the height of the

plane.

c. work The work input is the product of theinput effort and the length of the inclined

plane.

1-39


#Mechanical Advantage of the Inclined Plane

KEY WORDS

A commercially-made inclined plane withvariable height is often available in the labora-tory.

A simple, inexpensive, and rugged arrangementfor demonstrating an inclined plane is shown here.The plane is a 2 x 20 x 100 cm. smooth board witha pulley at one end. A notch is cut across theplane on the underside at the pulley end. Thesupport which fits into this notch is made of apiece of wood 2 x 10 x 30 cm., nailed at rightangles to a piece 2 x 10 x 20 cm. as shown.

This support can be used in three positionsto give three different heights to the incline.Either the long or the short member of the supportmay elevate the end of the plane, or the supportcan be laid on its side so that the 10-cm.dimension is vertical.

Place a wooden block on the incline to actas the resistance and pour sufficient sand intoa small tin can to provide the effort. Adjustthe amount of sand so that the block moves with aslow uniform velocity up the incline when started.The magnitude of the resistance and effort may bethen determined with precision by weighing them onan accurate balance that is centrally located inthe laboratory. Determine the mechanical advantageof the inclined plane in each position.

101

I -4- 0

REFEREN CE OUTL INE MAJOR UNDERSTANDINGS ANDFUNDAMENTAL C ONCE PT S


*Weight always acts in a downward direction

towards the center of the earth. When an object

is resting on an inclined plane, the weight is

resolved into two smaller components. One of

these components is acting in a direction that is

parallel to the inclined surface. The other

component is at right angles to the incline and

is fully supported by the surface of the plane.

Thus, the effort to move the object along the

plane can be relatively small because it only has

to overcome the weight component that is parallel

to the incline.

KEY WORDS

When an object is lifted, work is done. The

object has a greater potential energy due to its

position at a greater height. This increase inpotential energy is numerically equal to the work

output.

The work input would be equal to the workoutput under ideal conditions. Under actualconditions, however, an additional amount of work

is always required to overcome the frictional

forces between the object and the surface of the

inclined plane.

*Variations of a Lever--The Wheel and Axle

Models of a wheel and axle designed forlaboratory use are sold by science supply companies.

Laboratory manuals describe numerous experiments

in which they may be used.

The wheel and axle comprise a lever capable

of continuous rotation. Its ideal mechanicaladvantage can be obtained from its lever arms(the radii) or from the distances moved by effort

and resistance (the circumferences). Its value

lies not only in its numerous traditional appli-

cations but also in the usefulness of its

variants--the crank, and gear systems of all sorts.

103

1-42


3. variations ofthe lever

The-pulley and the wheel and axle.may be considered variations of thelever.

4. variations of the A screw is an inclined plane thatinclined plane is twisted into a spiral shape.

F. Compound Machines

A wedge consists of two inclinedplanes back to back.

Compound machines are composed oftwo or more simple machines whichact together to overcome a resistance.

104

1-143


AVariations of the Inclined Plane--The Screw

KEY WORDS

compoundmachines

The old-fashioned, screw-adjustment pianostool makes a good demonstration. Pass a turn of

cord around the top of the stool, seat a student

on it and pull the cord. Use a spring balance to

meas,Ire the force necessary to keep it turningonce started. The useful weight lifted is the

weight of the pupil. These figures determine the

actual mechanical advantages.

Calculate the ideal mechanical advantage from

the pitch of the screw and the circumference of

the stool. Compute the efficiency from the

mechanical advantages.

Call attention to the importance of friction

in increasing the usefulness of most screws. Also

point out that a screw is always used in combina-

tion with some sort of lever and is never used by

itself as a simple machine.

#Actual Machines

Pupils should have an opportunity to handle

and analyze real.machines which are not merelylaboratory model-s. If an overhead support has

been built in the classroom, the block and tackle

or chain hoist can be '1,1,1ed to lift large weights.

The jackscrew and the alitoziobile jack in their

numerous versions also lend themselves well to

the analysis.

The load to be lifted may be a student, or itmay be a bucket of wet sand or-plain water.

Compute th,2 ideal machanical advantage from the

dimensions of the machine or the distances movedby effort and resistance. Calculate the actualmechanical advantage from the forces actuallyused. Then calculate the efficiency from these

mechanical advantages.

if)5


II. Forces and Fluids

A. Density Density is a measure of the amountof matter in a given space.

Density is the relationshipbetween the mass of an object andits volume.

The density of some liquids can beincreased by dissolving substancesin them.

Note: There has been some confusiaqbetween the comparison of ml and cmpin volume measurements. The Inter-national Conference on Weights andMeasures in 1964 re-defined the literto avoid confusion:

1 milliliter (exactly)=1 cubic centimeter (exactl:

1 ml = 1 cm3

Similarly, a ml of pure water at itsmaximum density now has a mass of0.999 972 008 grams, not exactly 1 gm.The difference is so slight that ex-cept for very precise scientific work,one ml of H20 weights one gram.

Either ml or cm3 may be used bypupils at this level in relatingvolume relationships.

106

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#Density is sometimes confused witli weight.

Iron is more dense than wood, but it would beincorrect to say that iron is heavier than wood.

This distinction becomes apparent when we comparethe weight of a wooden door with the weight of aniron needle. Although an iron ship is heavy, thematter is dispersed so that the average densityof the ship is actually less than that of thewater on which it floats.

KEY WORDS

fluiddensity

If the density of a liquid is less than thedensity of a substance to be dissolved in it, thedensity of the solution will usually increasewhen the solute is added.

Densities of Various Liquids and Solids

Solid

Density

(g/cm3

) Solid

Density

(g/cm3

)

Bone 1.7-2.1 Porcelain 2.4

Brick 1.4-2.2 Rubber 1.2

Camphor 0.99 Sandstone 2.1-2.4

Clay 1.8-2.6 Slate 2.6-3.3

Cork 0.2-0.3 Wax, sealing 1.8

Granite 2.6-2.8 Wood:

Ice 0.92 Apple 0.6-0.8

Limestone 2.7-2.8 Balsa 0.1

Marble 2.6-2.8 Bamboo 0.3-0.4

Paraffin 0.9 Birch 0.5-0.8

Hickory 0.6-0.9

Maple 0.6-0.8

Oak 0.6-0.9

Pine 0.4-0.9

Poplar 0.3-0.5

Liquid

Density at Room

Temperature (g/cm3

)

AlcoholCarbontetrachloride

.0.8

1.6

Glyaerine 1.3

Kerosene 0.8

Mercury 13.6

Milk 1.03

Sea Water 1.03

Turpentine 0.9

Water 1.0

Metal

Density

(g/cm3)

Aluminum 2.7

Brass 8.2-8.7

Copper 8.9

Gold 19.3Iron 7.8

Lead 11.3

Silver 10.5

Zinc 7.1

1-46


B. 'ressure *

optional

Pressure is the force per unit-area.

Pressure is calculated by dividingthe total force by the area overwhich the force is applied.

Pressure is ekerted by solids,liquids, and gases.

I-147


'Units of measurement become especiallyimportant in differentiating among various physical

terms. Pressure is indicated by notations such as

5 newtons per square meter (5 nt/m2) or 2 centi-

newtons per square centimeter (2 cnt/cm2). Have

pupils realize the importance of habitually stating

the magnitude accompanied by the appropriate unit

of measurement. Thus, it would be correct to

state that a force is 5 newtons, but stating that

a pressure is 5 newtons would be meaningless.

KEY WORDS

pressure

..-Concept of Pressure

Have a student lift a weight, such as a I-kg.standard mass, by a fine wire looped to form a

handle. Then relieve his discomfort by using aroll of stiff cardboard for the handle--causingthe same weight to act on a larger area andreducing the pressure.

Cite such examples of high pressure as:

The pressure under the tip of a phonographneedle may be over one ton per square inch,

even though the force exerted by the tonearm is only a fraction of an ounce.

A girl teetering on one high heel exertsmore pressure on the ground than theEmpire State Building does.

Have pupils compute-the pressure they exert

on ice when ice skating. If snow shoes (or theirapproximate dimensions) are available, repeat the

computation.

!Force Developed by Air Pressure

Pupils may have seen this demonstration before.

Do not repeat if this is the case.

Normal air pressure is approximately 10newtons per square centimeter. After calculatingthe surface area of a large can and the force of

the air on its surface, remove the air from theinside by boiling a small amount of water and

1-48


1. variation ofliquid 'pressurewith depth.

The weight of a liquid causes itto exert a pressure.

Liquid pressure increases indirect proportion to the distancebelow the surface of the liquid.

MATERIALS

KEY WORDS

ACTIVITIES

allowing the steam to fill the interior. Remove

the heat and seal the can by screwing on its cap.When the steam cools, it will be observed thatthe can is twisted and collapsed by an invisibleforce that is comparable to the weight of an

automobile. This is an old classroom demonstra-tion that never fails to imp-ess those who have

not seen

#Variation of Water Pressure with Depth

The principle that water pressure dependsupon its depth can be demonstrated with theapparatus shown in the diagram below.

REFERENCE OUTLINE

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1-51

MATERIALS ACTIiITIES

#The difference in water pressure ondifferent floors in some buildings is frequentlyvery noticeable. The milk carton demonstrationshown in the'diagram should provide a basis forunderstanding the reason. Adjut;t the supplyentering the carton so that water continues toflow from all four holes in the side of the carton.

KEY WORDS

Some pupils may not know that very tallbuildings have water supply tanks above the topfloor. A picture showing the rooftops of anyolder city will reveal many of these tanks. In

more modern buildings these tanks are enclosedby the roof or placed in a tower.

I--52


*2. variation of

liquid pressurewith density

Liquid pressure varies directly-with density.

*3. direction of At any point pressure'is thepressure same in all directions.

1-53


KEY WORDS

#The principle that water pressure at any

depth is the -same in all directions can be

demonstrated with the apparatus shown in the

diagram below.

* Measuring the Upward Pressure of Water

The following is a technique which might be

used as an individual laboratory exercise formeasuring the upward pressure of water at various

depths.

Obtain a wide glass tube that is between 2

and 5 centimeters in diameter and is at least 15

centimeters long. If the end of the tube is not

perfectly flat when purchased, it may be preparedby grinding it with emery or carborundum powder.Then attach a thread to the center of a thin

square of glass (which should be just a little

larger then the hole in the glass cylinder) using a

water-proof quick-drying cement. Weigh the glass

square and string. Set up the apparatus as shown

in the diagram, holding the glass square to the

bottom of the cylinder with the thread until the

upward pressure of the water is sufficient tosupport the weight of the square. Weigh a small

container of sand. Release the thread and slowly

pour sand into the cylinder until its weight

3 5

REFERENCE OUTLINE

4. effect of theshape of thecontainer

1-54


Pressure is not affected by thevolume of the liquid or by theshape of the container.

1-55


KEY WORDS

overcomes the upward force of the water and glasssquare and the added sand will equal the upwardforce of the-water at the measured depth. Dividingthis force by the cross sectional area of thecylinder may be used to determine the waterpressure. If sufficient time is available, it is

suggested that this be repeated for various depthsof water. Graph the data.

#Intuitive thinking might lead us to believethat a large container of water would exert morepressure than a small container of water filledto the same depth. However, if a hollow tube joins

the two containers at the same depth, it isobserved that the water levels in the containerswill be exactly equal. This would be true onlyif the pressures were equal.

REFERENCE OUTLINE

C. Hydraulics and*Pascal's Law

1. transmissionof pressure

2. applicationof pressure

Optional

1-56


Pressure that is applied to afluid is transmitted equally inall directions without loss.

Comparatively large pressures maybe exerted on a confined fluid byapplying a force to a piston ofsmall cross sectional area.

1-57


#Hydraulic Pressure Transmission

KEY WORDS

Pascal's Law

To illustrate that pressure applied to afluid is transmitted equally in all direction,drill several tiny holes around the walls and inthe bottom of a small empty can such as used forfrozer orange juice. Make a close fittingpiston by nailing the top that was removed fromthe can to a dowel stick and covering it withseveral thicknesses of cloth secured with a rubberband. When the can is filled with water andpressure is applied to the piston, streams ofwater will shoot out in all directions.

Con t-op

Dowel

Clof-h heldwil-h rubberbond

Nail

#Use a hot water bottle to show the principleof the hydraulic lift. Insert a one-hole stopperand a piece of glass tubing in the mouth of thebottle. Make it as secure as possible. Attach a

5 or 6 foot length of rubber tubing tc the glasstubing and connect a funnel on the other end.

Now lay the bottle on the floor and place aflat piece of board on it. Ask a pupil to standon the board. Hold the funnel as high as possibleand pour water into it. Note the results. Thisdemonstration presents a good opportunity to discussthe difference between force and pressure.

119

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3. multiplicationof force

D. Archimedes'Principle

1. displacement

*2. buoyancy

Transmitted pressure can exert agreat force on a large surfacethat is in contact with the fluid.The magnitude of this force can beincreased indefinitely by increas-ing the surface area affected.

When an object is submrged, itwill displace a volume of fluid(liquid or gas) that is equal tothe volume *of the object.

An object partially or entirelyimmersed in a fluid has moreforce (due to the fluid) pushingup on the bottom tban force

pushing down on thetop.

The uplifting force of a fluid,called buoyancy, is equal to theweight of the liquid that theobject displaces.

00

I-59


KEY WORDS

Archimedes'Principledisplacementbuoyancy

#Determine the volume of a small solid bydropping it into a graduated cylinder that ispartially filled with water. Observe thedifference in water levels.

Lower larger solids into a can or tub thatis filled to the brim with water. Have the

pupils collect all of the displaced water and

measure its volume with a graduated cylinder.

When the object is fully submerged, the volume of

displaced water will be equal to the volume of

the object. If a laboratory-type overflow canis used for this experiment, a little vaselineshould be rubbed at the end of the spout toprevent seepage in order to obtain accurateresults.

#Archimedes' Principle for Floating Objects

Put an overflow can on one pan of a balance,

fill it with water, and balance it accufately,after allowing the excess to flow off into abeaker. Now lower into it a block of wood andwhen the wood is floating freely and the water

has stopped overflowing, the apparatus will again

be balanced, showing that the weight of the wood

exactly equals the weight of the water displaced.

1-60


3. apparent lossof weight

122

While an object is submerged ina fluid, it will "appear" toweigh less.

MATERIALS

KEY WORDS

1-61

ACTIVITIES

'Apparent Loss of Weight

Does an-object immersed in a liquid really

lose weight? Or is its weight merely transferredto some other support?

Weigh the object in air. Note the readingwhen the object is in water as shown. Comparethe change in reading of the platform scale withthe decrease in reading of the spring balance.

Mark the new water level with a rubber bandaround the outside of the container, and afterremoving the sinker, add water to the cortaineruntil the scale reading is the same as when thesinker was under water. The new water level willbe even with the rubber band, showing that theapparent difference in weight is the same as theweight of the displaced water.

REFERENCE OUTLINE

4. flotation

1-62


An object will float when the'buOyant force is equal to theweight of the object.

MATERIALS

KEY WORDS

1-63

ACTIVITIES

71tuoyancy Puzzles

a. How -can you change the condition ofequilibrium of the balance without touching thebalance or beaker, or adding or removing water?

(Dip finger into water.)

b. Push several thumbtacks into the baseof a short piece of candle so that it just floats.

Float the candle in a beaker of water, light itand ask the class to predict whether the candlewill sink, float higher, or remain at the samelevel as the wax is burned. Of course, thisdemonstratJon should be started at the beginningof a Period.

c. Can an object float in less than its own

weight of water? Use two containers of almost thesame diameter, so that the smaller one fits freely

in the larger, but without much space between.Load the smaller of the two so that it floats deepin water, then float it in water contained in the

other. Show by weighing that it is possible forit to float in less than its own weight of water.Have the class explain this apparent violation of

Archimedes, Principle.

d. What happens to the water level in apond if a boy drops a rock off a raft into thewater? Put enough lead shot in the bottom of abeaker so that it will float in water withoutoverturring.

Add as heavy a brass weight as the beaker

will hold while remaining afloat. The weightshould have a piece of string attached to it so

that it can easily be removed from the beakerafter the water level in the jar has been marked.

Remove the weight from the beaker placing it in

the battery jar. How do the water levels compare?

If this experiment had been performed on the Panof a triple beam balance, what changes in indicatedmass would have occurred?

Variation: What haPPens to the water level in

a pond if a boy jumps off the raft he has been on

-125

1-64


E. Bernoulli'sPrinciple

The pressure of a moving columnof fluid is affected by thevelocity of the fluid.

The greater the velocity of fluidthe lower will be the pressure atthe sides.


KEY WORDS

and floats? Instead of the brass weight use a

block of wood in the above experiment.

Variation: What happens to the water levelin the ocean when a ship sinks? Tip the beakercontaining the weight so that it fills withwater and sinks to the bottom. Or use a thickcafeteria-type coffee cup as the ship.

e. What happens when the ice cubes floatingin a brim full glass of water melt?

#Application of Bernoulli's Principle

Observing applications of the Bernoulli effectin the science laboratory presents an unusualopportunity for the pupils to "discover" one ofthe major principles of science from firsthandevidence.

a. Hold a plastic (or glass) soda strawvertically with the bottom immersed in a beakerof water. Use a second straw to blow air hori-zontally across the top. Note what happens tothe height of the water through the transparentstraw.

A low pressure is created below the movingair column in accordance with the Bernoulliprinciple. Pupils should be able to draw theconclusion that the height of the liquid variesdirectly with the speed of the horizontal airmovement.

b. Insert a funnel into a 20 to 30 cm.

length of rubber tubing. Holding the funnelupright, challenge the pupils to blow the ballout of the funnel.

The harder the pupils blow, the faster theair moves about the sides of the ball. Thecomparatively high pressure of the surroundingair prevents the ball from leaving the low pressurearea which is formed in the funnel.

127

-REFERENCE OUTLINE MAJOR UNDERSTANDINGS AND


I-67


KEY WORDS

Bernoulli'sPrinciple

If an air compresser or vacuum cleaner isavailable to deliver a steady stream of air intothe tuoe, the funnel may be inverted withouthaving the ball fall out.

c. Insert a pin through the center of asmall square of cadboard and rest it on athread spool so that the pin extends into thehole and prevents the cardboard from slidingoff. Using a straW, have pupils blow upwardinto the spool hole and try to dislodge thecardboard.

The air moving outward along the bottom ofthe cardboard creates a low pressure in accordancewith Bernoulli's Pl-inciple making this apparentlysimple task very difficult. While blowing inthe hole, have pupils try to invert the spoolwithout losing the cardboard. Have them explainwhy the cardboard al15 off as soon as the blowingstops.

d. Demonstrate another application ofBernoulli's Principle bY folding the ends of anindex card down to maxe a small bridge. Placethe bridge on a table and challenge the pupils toupset the bridge by blowing under it as hard asthey are able. Blowing underneath the bridgereduces the air pressure and the comparativelyhigh air pressure 1"rom above holds the bridgedown with increastqg force as the speed of theair below increases.

1 8

1-6 8

REFERENCE OUTLINE MAJOR UNDERSTANDINGS ANDFUNDAMETAL CONCEPTS

IV. Force and Motion

A. Speed -Speed is the rate at which dis-tance is covered in a unit periodof time. (The direction of travelis not considered in measuringspeed.)

B. Velocity Velocity is the speed of an objectin a given direction.

130

1-69


#Determining the Speed of a Moving Object

An object should be moving slowly at auniform rate when pupils measure the distancetraveled and the elapsed time. Suitable devicesthat meet these specifications are toy electrictrains and many battery operated toys.

Have one of the pupils act as timekeepercalling time every 5 seconds while another pupilmarks the position of the moving object at eachtime interval. If the object is moving at auniform rate, it will be found that consistentresults for the speed will be obtained by dividingany of the measured distances by the correspondinginterval of time.

Some pupils in the class should be able toplot a simple graph of distance versus time usingthe measured data. When the various points areconnected, the curve should be essentially astraight line.

KEY WORDS DISTANCE( IN SUITABLE

speed UNITS )

velocitydisplacement

0 5 10 15 20 25 30 35 40 45 50 55 60

TIME IN SECONDS

Velocity is a vector quantity that incorpor-ates both speed and direction.

#Difference Between Velocity and Speed

Have the pupils calculate the average speed ofa slowly moving toy electric train by dividing thedistance measured along a semicircular track by thetime it takes the train to cover the distance. Now

I -7 0

f"--P10E OUTLINE MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

1-71


measure the straight line distance between theinitial (A) and final (1B) position of the train.This straight line distiance is called the dis-placement. The average velocity of the train isobtained by dividing the displacement by the timeit took the train to go from A to B. Note thatthe values of the average speed and averagevelocity are different for this situation.

A

KEY WORDS

REFERENCE ouTLINE

1-72


C. Acceleration_Acceleration is the change orvelocity in a given time period.

units ofmeasurement

134

Acceleration is also defined asany change in a velocity.

Acceleration is expressed as avelocity change per unit of time.

A unit of acceleration is anyunit of velocity divided by aunit of time.

1-73


KEY WORDS

#In non-scientific usage, the termacceleration has peen limited solely to thechange of velocity by increasing speed. Becareful to point out that decreasing s peed andchanging direction are also implied in thescientific definition of ve1ocity change. Inperforming calculations, it is customary to asea + sign for positive acceleration and a - signfor negative acceleration.

*Have the pupils practice reciting accelera-tion units for a brief time so that they willhave greater meaning. This may be done bystating a velocity, "centimeters per second"followed by a pause, then adding "per minute."Caution the pupils not to state units of squareseconds. For example, 2 cm/sec2 is stated,"two centimeters per second...per second." Thispronunciation enhances the concept that an objectis gaining speed so that for each second oftravel the speed is increasing so that it is2 centimeters per second faster than it was theprevious second.

Examples of a variety of units of accelera-tion are:

After blast-off a rocket which isincreasing its speed at the rate of4 kilometers per hour each second, isaccelerating at 4 km/hr/sec.

FN,iction which reduces the speed ofa sliding object by one centimeter persecond for each second, results in anacceleration of -1 cm/sec2.

Acceleration is a vector quantity, but it iscustomary to state the direction on7y in caseswhere confusion would result or where the direc-tion is not obvious.

In3

1-74


2. examples

a. increasedspeed

b. decreasedspeed

A positive acceleration occurswhen the speed of an objectincreases.

A negative acceleration occurswhen the speed of an objectdecreases. This is also knownas a deceleration.

1-75


#Uniform Acceleration

KEY WORDS

acceleration

Positive acceleration is the rate of increaseof velocity with the result that greater distancesare traveled during successive time intervals.This is difficult to show with free fall becauseof the magnitude of the acceleration. Theacceleration of gravity may be "diluted" however,in several ways, so that the decreased motionand increased time make observation easier.

It may be desirable to use a metronome orpendulum to measure equal time intervals.Distances traveled in successive equal intervalscan be marked.

a. One of the simplest methods of studyingacceleration is by use of a roller on an incline.If a ball is to be used, it may roll in a groovebetween: (1) two steel rods, (2) two strips ofwood, (3) tongues of two flooring boards,(4) corners of two chamfered boards nailedtogether, or (5) two parallel pieces of bandironscrewed to a board. Such an incline should be6-8 feet long with one end elevated enough sothat the ball rolls smoothly and slowly in thegroove.

(1) (2) (3) (4) (5)

A cylinder such a 100-gm. brass weight, ifstartd accurately, will roll smoothly down aflat plank. A strip of glass 2 or 3 feet longand 5 inches wide makes a low-friction inclinedown which a weight will roll very easily.

In either case, measure the length and timeand compute the final velocity and the acceleration.

The ball also can be permitted to roll ontoa section of track which has been previouslyadjusted to slope just enough so that the ball

3 37

I -7 6


138

1-77-


KEY WORDS

neither accelerates or decelerates. Measureboth the time it spends on this section of thetrack and the length of the track. Compute the

final velocity. From this find the averagevelocity on the incline. By u-Ing the lengthof the incline, calculate the time spend inaccelerating and the acceleration. This can be

compared with the acceleration measuredpreviously.

b. The incline mentioned above may terminate

in a horizontal section on which the ball will beretarded for a study of deceleration.

c. A large, low-friction pulley can bearranged to support two masses which differ

slightly. By adjusting the difference in mass,acceleration can be made very slow.

d. A low-friction car can be acceleratedby the dropping of a weight at the end of a cord

passing over a pulley.

e. Determine the acceleration of an auto-

mobile by measuring the time it takes to achieve

a certain speed from a standing start. If it is

possible to measure or make a reasonably accurateestimate of the distance traveled while accelera-ting, compare this with the distance calculatedfrom the time and the acceleration. Disagreement

may be caused by the fact that the acceleration

of an automobile is not usually uniform.

f. Have students prepare a graph of a

uniformly accelerating object by plottingdistance traveled against time.

REFERENCE OUTLINE

c. change indirection

3. acceleration dueto gravity

a. universality

b. direction

c. magnitude

d. effect of airresistance

1-78


A central acceleration occurswhenever an 3bject is moved ina. path that is not a straightline.

The attraction between the earthand some other body is known asgravity.

Because of the pull of gravity,all objects near the surface ofthe earth accelerate during freefall.

The direction of the gravitationalacceleration is towards the centerof the earth.

The magnitude of the gravitationalacceleration is approximately9.8 m/sec2 in the MKS sxstem ofmeasurement. (32 ft/secq

Air resistance decreases theacceleration of objects duringfree fall.

140

I-79


KEY WORDS

accelerationof gravity

#A good example of a central accelerationis an object revolving at a constant speed ofone revolution per second. Its velocity isconstantly changing and it is being acceleratedat all times. The acceleration is directedtoward the center of revolution and so iscalled a central acceleration.

#Acceleration of Gravity Independent of Mass

Suspend two balls of the same size as highas possible above the floor by means of electro-magnets. One ball should be iron; the othershould be wooden with a nail in it. (Two steelballs of different sizes may also be used.) Coverthe pole of each magnet with a piece of cellulosetape. Connect the magnets through a switch to adry cell. Place a metal pan or metal wastebasketunder the balls. Open the switch. Note that onlyone sound is heard when the balls strike the metal.

The letter "g" is an abbreviation for theacceleration of gravity.

At increased altitudes, the pull of gravitydecreases and the value of g varies accordingly.Within a few hundred meters of the surface ofthe earth, this effect is small and cannot bedetected with the usual laboratory instruments.Therefore, for practical purposes, the accelera-tion of gravity may be considered to be a constantvalue for laboratory experiments.

#Effect of Air Resistance on Acceleration

a. The dependence of air resistance onarea and the concept of terminal velocity can beshown with a sheet of paper. Dropped in ahorizontal position, it quickly reaches its

terminal velocity. Dropped edgewise, it plummetsto the floor. Crumpled loosely, it falls quickly,but does not keep pace with a metal ball or coindropped at the same time. Wadded into a tightball and dropped with a metal object, it fallsalong with the other, and strikes the floor atabout the same time.

REFERENCE OUTLINE

D. Newton's Laws ofMotion

1. Newton's FirstLaw--inertia

142

1-80


An object resists efforts tochange its velocity.

An object at rest resists effortsto start it in motion.

A moving object resists effortsto increase its speed.

A moving object resists efforts todecrease its speed or stop it.

A moving object resists efforts tochange its direction of movementfrom that of a straight line.

Inertia is that property of matterwhich enables matter to resistefforts to change its velocity.

1-81


b. The "guinea-and-feather" tube is usedto show that the acceleration of freely fallingobjects is independent of mass if air resistance

is eliminated. This is a large glass tube con-taining a feather and a coin. At normal pressurethe feather flutters and the coin plunges asexpected when the tube is inverted. But whenthe air is removed, the feather and the coindrop together.

#Demonstrations of Inertia

There are many relatively simple demonstra-tions which pupils can use to illustrate the

principle of inertia. The following areillustrative:

a. Snatch a piece of paper from underneatha glass of water after showing that the glasscan be dragged along by gently pulling the paper.

b. Stand a book on edge on a strip of

paper and show that, if pulled slowly the bookwill move along with the paper, if pulled morequickly the book will fall over, and if thepaper is snapped out, the book remains standing.Have pupils explain how the laws of motionaccount for the behavior of the book in each of

KEY WORDS the three cases. Discuss tne part played byinertia when subway "strap hangers" lurch as the

Newton's First train starts or stops suddenly. Call attention

Law to inertia as the cause of injury and damages.inertia in automobile accidents.

c. Rest a coin on a card placed flat on

the tip of one finger. Flick the card out fromunder the coin with a finger of the other hand.The card should be about the size of a callingcard, and the coin a quarter or larger in orderto make the demonstration effective.

d. Make a stack of 5 or 6 checkers andknock the bottom one out by striking it with aruler. Repeat until you are down to the lastchecker. Coins can be used, and a hacksaw blade

or knife blade used flat to strike out the bottomone.

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1-83


KEY WORDS

e. Suspend a massive ball such as a 25 kg.

shot by a cord. The ball should be drilled at

ends of a di:ameter for hooks. A similar cordis attached to the bottom. A gentle pull onthe lower cord breaks the one supporting theweight. The falling ball may be caught in thehand or allowed to drop into a bucket of sand or

onto a pad of rags. A sudden pull achieved byswinging the arm breaks the lower cord. Havepieces of string of the proper length and withloops tied in the ends ready for quick replace-ment.

f. Hang a heavy ball, with a hook on oneside, as a pendulum. Using a length of lightcord, show that the pendulum can be drawn asideif pulled gently, but that the cord breaks ifyanked suddenly, resulting in almost no dis-placement of the pendulum. Attach the sidestring to a fixed upright, using a length thatwill be slack until the pendulum reaches thebottom of its arc. Draw the pendulum toward the

upright and release. Note that the cord willbreak when it is pulled taut.

g. Use a large knife to cut part waythrough an apple or a potato. Then strike theknife, cutting blade up, on the edge of thetable to slice through completely. Or with theknife part way through the object, hold it inthe air and strike the back of the knife a sharpblow to finish the cut.

145

REFERENCE OUTLINE

2. Newton's SecondLaw--overcominginertia

a. the inertia ofobjects atrest

b. the inertia ofobjects inmotion

c. magnitude ofmass

1-84


An unbalanced force will cause an-object to accelerate.

An unbalanced force applied to anobject at rest will result in anacceleration in the direction of

the fcrce.

A force applied to a moving objectwill cause it to increase speed,decrease speed, or change direc-tion of the force with respect tothe direction of the originalmotion.

Other things being equal, thegreater the mass of an object,the more difficult it is to over-come its inertia.

14-B

MATERIALS

KEY WORDS

1-85

AlVI

14eVit second law of motion,#According tO irry,t1151 v proportional to the

the acceleration jejot)0;1-,se-s-J 4_

mass and directly p'otl-leal L,0 the applied

tioll lly a 4 whereforce. Expressed 01 4),4tica ,

),'/Ilz)/1 ojsec2a Is the acceleraf is the force in,,ciansm is the mass in

development of allA thorough quaeort-ore for all pupils.

these concepts Is i'orlou)WI% reserved for pupilsNumerical problems og b

elementary algebra.liwith a good grondl'od L

#Newton's

To illustrate 14e9tkl's11:11roTril: =Me,two pulleys as h40-11,1

sopass a piece of'.je-g. ZN. It;11:1;11d1TotclelreTtethat a weight ha.nge'at c-Nnt,--eother end is near thefloor when a hanger, (m r.e ,o of 100 gm. 20 gm.,pulley. Put 150

g1110 l'''dard masses) on onetan10 gm., 5 gm., knd oth,1 s just enough moreside and adjust the .cends with uniformthan 150 gm. so tha (I,de$2ce_5 are used to holdspeed once startedqh b`",.ht hangers, it will

the weights ratheravoid the neceszitYAt.).L-ItoK

g up dropped weights

during the expebine

sta a mass is transferredNewton's Second Now if a 5...E1701, to -'-tt6-- a roecond, there is anLaw from the first zide,pito, he a total mass of some-unbalanced force a001.° on

what more than 30o 'OcTin,laclthe system willri to determine the

accelerate. Use a Asz-"ratot it takes the /31:N. to drop from its highest

oure the distance andposition to the fl001,t,Nle3 Transfer anothercalculate the aeceJ, to 'coni..sle the unbalanced5-gm. standard kas5,0.1-te'tou' acceleration. Con-force and again colivi 1.0,_the,,,,d calculating thetinue increasint trel c,oe y'is so great thatacceleration until 0. lz)ee at the accelerationtiming is unreliahl,,01 hoWetil

to 20 bY Plotting the datais proportional (3-1orci any irregularitieson graph paper. AOin the curve dremn,

.147

1-86


143


KEY WORDS

In similar fashion, by keeping the unbal-anced force constant, the total mass can be

varied and the acceleration shown to be inverselyproportional to the mass. Variation in frictionloss makes this inaccurate, but correcting forfriction at each trial is tedious.

#Coaxing a Coin with Inertia

A given force will produce a greateracceleration on a small mass than on a larger

one. An amusing parlor trick is based on thisprinciple. Lay a handkerchief on a table andset an inverted glass tumbler in the center.Place a dime under the tumbler and support therim with three pennies so that there is a smallopen slit between the handkerchief and the glass.Challenge the pupils to remove the dime withoutdisturbing or making any contact with thetumbler. If the handkerchief is scratched witha fingernail, the short jerks of the cloth willcause the dime to accelerate towards the beckon-ing finger. The larger mass, consisting of theglass and pennies, being more difficult toaccelerate, will have no apparent movement.

149

1-88


1:59

1-89


KEY WORDS

#The Laws of Motion and the Hydraulic Ram

The hydraulic ram may be used as an illus-tration of inertia and also to help with energyconcepts. Glass models are sold by sciencesupply companies, but a homemade version can beconstructed.

Invert a large bottle from which the bottomhas been cut. In its mouth insert a stopperfitted with a bent section of large diameterglass tubing. Couple a glass T to this andterminate over the sink with a three-inch pieceof thin-walled rubber tubing. A delivery tubeto carry water to a beaker (representing a homesupply of water) is connected to the third armof the T.

It is essential that there be no constric-tions between the bottle and the sink so thatflow of water is rapid. Pinch the rubber outletsuddenly and the water rises in the deliverytube. With sufficiently rapid water flow, thewater in the delivery tube can be raised higherthan the supply level, so that some water canbe transferred to the reservoir.

Supply

T-Pub

Reservoir

S ink

Discussion of the first and second lawusually involves the effect on passengers whenan automobile slows down or speeds up rapidly.It should be stressed that the passenger isnot propelled forward or pushed backward whenthe brakes are applied or the car accelerates.The inertia of the passenger tends to keep himin motion or at rest. Unless seat belts orsomething similar are used, the force betweenthe clothing and the seat alone is not largeenough to bring about the change in motion inthe time available.

REFERENCE OUTLINE

3. Newton's ThirdLaw--action andreaction

a. relation toforces

1-90


Every action is accompanied by a-reaction this is equal in magni-tude and opposite in direction.

It is impossible to ekert a forcein a given direction withouthaving an equal force in theopposite direction at the sametime.

152

MATERIALS

KEY WORDS

Newton's ThirdLawactionreaction

1-91

ACTIVITIES

#Newton's Third Law

A correct statement of Newton's Third Lawis: When two particles (or bodies acting likeparticles) interact, the force acting on thefirst is equal in magnitude but opposite indirection to the force action on the second.

To show the recoil due to a water jet,

use a 100 cm. length of light, flexible rubbertubing. Tie a piece of string about 10 cm. longon the tube at two points, so as to pull it intoan approximate right angle turn. Attach the tubeto the water faucet and turn on the water cautious-ly. With the water flowing gently, the tubestands out in a most unnatural position. If thewater is turned on hard for a moment, itswrithing is most instructive, but will showerwater on a good portion of the classroom.

#Action, Reaction, and Acceleration

Connect two small cars, such as are often usedwith the inclined plane, by a long, thin rubberband. Now if they are drawn apart to stretchthe rubber band, equal and opposite forces areexerted on the front of each car to reduce theshattering effect of the collision. Resultswill be most reliable if the cars are identicaland wheel-bearing adjustments and lubricationmake the friction in them as nearly alike aspossible.

If equal masses are carried by the cars,their point of meeting will be equally distantfrom the two starting points. If the total massof one is twice that of the other, it will travelhalf as far before the collision. (The forces

15:3

REFERENCE OUTLINE

b. relation tomomentum

E. Conservation ofmomentum

1. increasingmomentum

2. decreasingmomentum

*optional

I-92


Momentum is the product of themass and its velocity.

An increase in momentum isaccompanied by an equal increaseof momentum in the oppositedirection.

Momentum cannot be created nordestroyed.

The momentum of an object may beincreased by decreasing themomentum of another object.

The momentum of an object may bedecreased by increasing themomentum of another object.

154

MATERIALS

KEY WORDS

momentumconservation ofmomentum

1-93

ACTIVITIES

are the same except for small differences infriction, and the acceleration must be inverselyproportional to the mass. The distance isproportional to the acceleration.) Use uprightcardboard indicators on the table to mark thestarting points of the cars.

Bring out the point that this might be used

as a method of measuring mass, a method whichdoes not involve weight in any way.

#Action and Reaction with a Skateboard

a. Have a pupils stand with his left footon the ground and his right foot on a skateboard.Call the attention of the class to the backwardmotion of the skateboard as the pupil stepsforward with his left foot and attempts to keepthe right foot still. This demonstration worksbest with a smooth floor.

b. Have two pupils stand on skate boardsfacing each other. Show that it is impossiblefor either pupils to move the other withoutmoving himself in the opposite direction. If

the two pupils are approximately the same size,they will move with equal velocities and coastthe same distance. If one pupils is very muchsmaller than the other he will always move fasterwhether he is pushing the larger pupil or isbeing pushed.

This relatively complicated topic may be

discussed qualitatively. Excellent examples arecollisions of billiard balls, two automobiles,travelling in the same or different directions,and so forth.

#Recoil and Conservation of Momentum

a. The effect of recoil can be simplydemonstrated by this experiment. Put some waterin a small bottle, stopper it with a solidrubber stopper, hang it horizontally by twostrands of light wire (no. 30) and heat itcautiously. When the stopper pops out, the

1-94


1-95


KEY WORDS

bottle will recoil and some of the hot waterwill be spilled vertically below the support.All three of these phenomena should be discussedand explained in terms of Newton's law of motionand the law of conservation of momentum.

b. A more complex device to show theinfluence of recoil is constructed as follows.Prepare a platform approximately 1 x 4 x 5 ".Suspend it as a swing by thin wire (no. 30) fromfour screw eyes in the corners. Attach a stripof rubber (a heavy rubber band will do) to twonails near one end of the platform and hold itback with a loop of string passing over asupport made of a bent nail, and down to a nailon the opposite side of the swing. If a ballsuch as a heavy pendulum bob is placed in thepocket formed by the rubber band, and the stringis burned by a match flame held below the nail,the ball will be shot out and the platform willrecoil.

Prepare loops of string of the same lengthso that the "gun" can be reloaded quickly tocompare the effect on the bullet and the swingwhen balls of different masses are shot.

157

1-96


3. exchange ofmomentum

Momentum can be exchanged by twoobjects that collide, but thetotal momentum after. such aninteraction is always eaual tothe momentum before the event.

1-97

MATERIALSACTIVITIES

#Conservation of Momentum and Kinetic Energy

KEY WORDS

The construction of this device is an inter-

esting extra-class project for some pupils. It

is doubtful that the teacher should spend the

time on constructing it.

Make a wooden frame 140 cms. long, 30 ems.

high and 10 cms. wide. Suspend seven steel

balls of equal size from the top edges of the

frame. (An eighth ball somewhat larger in size

may be added later to make the demonstration

more complete.) The balls should be at least

3 ems. in diameter or preferably larger. The

cord is passed through and knotted on two metal

It ears" soldered to the ba1L. The points ofsupport are screw eyes with two loops of cord

taken around the shank so that the position of

each ball can be adjusted by turning the screw

eyes from which it is suspended. The positions

of the points of support for adjacent balls

should be exactly as far apart as the diameter

of the balls used. If a larger ball is used,

suspend it the same way at the end of the line

with its points of support a little farther

from the others to make up for its greater

diameter.

Bore 2-cm. holes in a line through the

top; these can be used to hold the balls not

being experimented with. Make tabs of card-

board bent at a right angle and cut to a point

on top, and high enough so that they almost

touch the balls. These tabs are used as

indicators to mark the positions of the balls

at various parts of the tests.

If the large ball is placed on top of the

frame, with the remaining ones accurately lined

up, and one of the small ones drawn back and

allowed to strike the line of balls, a single

ball will be driven out from the other side.

The impact of two balls will cause two to swing

out, and so on.

159

1-98


1-99


If all the balls except two adjacent onesare put on the top out of the way, it can beshown that when two equal balls strike, thereis an exchange of velocities.

KEY WORDS

If the large ball is stationary and isstruck by the small one next to it, it can beshown that the smaller one does not transferall its kinetic energy to the large one, butrebounds.

This rebounding can be used to help explainthe choice of material for moderators in anuclear reactor since the transfer of energy isgreatest when a neutron strikes an atom mostnearly its own mass.

* #The Laws of Motion and Conservation ofMomentum

The laws of motion and conservation ofmomentum may be illustrated in the followingmanner. Hang a weight from a spring supportedby a clamp on a ringstard. Choose the lengthand strength of the spi_ig, and the size ofthe mass to provide for as long a period ofoscillation as practical. With the apparatusresting on the desk and the weight bobbing upand down, discuss the part played in theoscillation by the inertia of the weight, asits extension changes. When this has beenthoroughly discussed, ask the pupils whetherthe table supporting the ringstand is playingany part in the oscillation. After an expressionof opinions, place the apparatus on the platformof a balance designed to handle large weights,and balance it with the weight quiet. Holdingthe balance stationary, start the oscillation

161

I-100


I-101


KEY WORDS

and then release the balance. Explain theresult in terms of the forces and also in termsof conservation of momentum.

The principle of conservation of momentumis presently having considerable applications inpredicting reactions that occur after collisionsof sub-atomic particles. It has also beendetermined that electromagnetic waves such asX-rays and photons interact with small particlesof matter which results in changes of momentum of

the matter. If the energy in the electromagneticwave is equated to mass in accordance withEinstein's equation, E = mc2, the law of conser-vation of momentum has been found to hold trueeven in these special cases.

163

ikoC14

Ttig

le 4

J-1

BLOCK J - CHEMISTRY OF MATTER

Introductionsafety in the laboratorytools of the chemist

Properties and Changes in Matterphysical and chemical propertiesphysical and chemical changes

Introduction to Atomic Structureprotons, electrons, neutronssimple atomic model (Bohr)periodic tablearrangement - atomic numbers

Common Chemical Changessimple representative examples (laboratory)simple explanation based on periodic tablechemical shorthand

common Compounds and Mixturesacids, bases, and saltssolutions and suspensions

interpretation of solubility charts

Introduction to Organic Chemistry

Role of Chemistry in Our Societychemical advancesconserving chemical resources

J-2

REFERENCE OUTLINE MAJOR UNDERSTANDING ANDFUNDAMENTAL CONCEPTS

I. Introduction

A. Safety in thelaboratory

1. rules of safety

A laboratory is as safe as theleast safe person. It is theresponsibility of each pupil toavoid accidents.

Prevention of accidents requiresknowing what to expect and how toperform the experiments as wellas maintaining a quiet, business-like manner.

a. general rules Read, understand, and followdirections; when in doubt, ask theteacher. Work quietly, thought-fully, and avoid rushing but alsoavoid wasting time.

b. prevention ofinjury

A laboratory is no place in whichto eat or drink. Avoid any situa-tion which may lead to any chemicalbeing taken internally. Mostchemicals are poisonous.

Keep your face away from the workarea. Protect your clothing andeyes by wearing rubber aprons andgoggles or eye shields, Manychemicals "eat" holes in clothing.Spattering of liquids or flyingparticles from a shattering sub-stance can cause serious eyeinjuries, cuts, and chemical burns.

Wash away with quantities ofwater any chemical spilled on theskin, clothing, or desk. Manysubstances can burn or irritatethe skin; others can cause firesor other reactions to occur.

Keep the desk, equipment, andhands clean at all times.

Use only a clean spatula to trans-fer solid chemicals.

166

3-3

MATERIALSAcTiy.$Is

SAFETY

fAsk smile ,e moreZtIstically talentedHang the chartspupils to prePS;.; Za.fea

in the room to )' 1711Arld p0P- Of their responsibilityfor safety.

d eCollect ari t

science papers

cart ons based upon labora-tory safety.

Arld kag0% most often found in

-rto°11,1ear

UNIVER)OT$Mix thoro0OhlIt ne Pa1*6t by weight of magnesium

0 acidoxide, one part, ' d wo parts powdered

t a clean, dry con-charcoal. PlaO` the ml/cte ntainer and label' It witD

tlame and dosage: one/ /gall

heaping spoonf0 II a 0 glass of warm water.

Store the °Iltldote in th% first aid supply area.

KEY WORDS

bUrnbusiness-likeinternallyirritatespatula

REFERENCE OUTLINE

4

C. accidentprocedures


While pouring liquids, hold thebottle stopper or cork so thatliquid will not get on the desk orother materials get on the cork.

Traces of chemicals can causesome other materials to react ordecompose violently.

When observing the odor of a sub-stance, fan the gas toward yournose. Do not put the nose directlyover the material. Some substancesare poisonous, others can irritatethe membranes of the respiratorysystem.

Know how and when to use thesafety devices. Use the fireblanket when a person's hair orclothing is on fire. Use thecarbon dioxide fire extinguisherfor other fires.

Report all accidents, even thesmallest ones. An injured personmay not realize he needs first aid.

Knowing what caused an accidentcan help prevent its reoccurring.

MATERIALS

gPaduatesreagent bottleswater

J-5

ACTIVITIES

POURING LIQUIDS

Demonstrate the proper procedure to usewhen pouring liquids from a bottle. Then havethe pupils measure specific amounts of theliquids from the reagent bottles.

KEY WORDS

decomposeextinguishermembraneodorrespiratory tractstopper

(Colored water makes a good starter.)

OPERATING SAFETY DEVICES

Be sure that pupils know when and how tooperate a fire extinguisher or apply a fireblanket.

Demonstrate how to use the carbon dioxide fireextinguisher. Point out that it is never directedat a person because serious cold burns can resultfrom the solid dry ice touching the skin. If a per-son's clothing gets on fire, a fire blanket is used.

TEACHER NOTE:

Always use goggles when there is a danger ofspattering, chipping, breakage, snapping, etc.

169

J-6


B. Laboratory tools

1. burners

a. structure The parts of the burner are thespud or gas opening, the air holesor ports, and the barrel.

Operation of the burner is based uponBernoulli's principle. As the gasunder pressure is released throughthe small opening of the spud, thereis an increase in the velocityof the gas causing a reduced pres-sure in the gas stream. Air rushesin through the air ports due topressure differences, and acombustible air-gas mixture passesup the barrel.

b. function Controlling the rate of burning ofa fuel provides a safe supply ofheat energy for laboratory use.

C. nature ofthe flame

In order for burning to occur,there must be a fuel, oxygen, orair, and sufficient heat toreach the reaction temperaturecalled the kindling temperature.

When a proper air-gas mixture isobtained, the gas burns with apale blue flame and has a cone-likeappearance. There is enough airbeing supplied to the burner forthe fuel to be completely burned.

The hottest point of the flame isat the tip of the inner blue cone.The hottest part of the flame iscalled the reducing flame.

The tip of the outer flame isrelatively rich in oxygen and isreferred to as the oxidizing flame.

J-7


KEY WORDS

Bernoulli's Principleburningheatkindling-temperatureluminousoxidizingpressurereaction temperaturereducedreducingspudvelocity

171

REFERENCE OUTLINE

.1- 8


The coldest part of the flame isinside the inner blue cone whichconsists of unburned gas and air.Things held inside the cone willnot get hot.

If the air openings of a burnerremain closed or not sufficientlyopened, the flame will be yellow,luminous, and sooty. The fuel isnot being completely burned.

If too much air is admitted, theburner "roars" and the flame maystrike back causing the gas toburn inside the barrel. The barrelgets very hot.

When a burner strikes back, turnoff the gas, close the air ports,relight the burner, and readjustthe air intake.

d. safety rules Light the match, then turn on thegas. If too much air-gas mixtureaccumulates, an explosion can occurwhen a match is lighted.

When lighting the burner, keep theface and other parts of the bodyto one side of the burner. Neverreach across a burner. Hair andclothing can be set on fire.

Always apply heat gradually and evenly.

When heating a test tube, point themouth of the test tube away fromyourself and others. As the liquidbegins to boil, it may spurt outacross the desk and burn someone.

Keep materials being heated at theback of the desk. If anythingbreaks or spills, there is lessopportunity for someone to get hurt.

MATERIALS

asbestos padwaterpotassiumpermanganateglycerinetripod stand

Fuel

J-9

ACTIVTTIES

FIRE TRIANGLE

Oxygen

Heat

1. Discussion of Fire Triangle infire prevention

2. Discussion of spontaneous combustion

3. Introduce terminology sUch asoxidation (slow and rapid)combustionkindling pointflash point

Discuss their interrelationships

Demonstrate spontaneous combustion as a resultof slow oxidation. Make a small cone-shaped pile ofpotassium permanganate crystals on an asbestos pad.Moisten it slightly and add a drop or two ofglycerine. In a minute or so it should burst into

flame.

J-10


J-11

ACTIVITIES

THE BURNER AND ITS FLAME

Allow each pupil to examine, dismantle, andreassemble a burner to identify its parts.

Demonstrate the proper way to ignite and adjustthe burner.

Emphasize the need for lighting theand not reaching across the burner.

Have the pupils study the differentduced when the amount of air is varied.

match first

flames pro-

Place a Pyrex beaker of cold water on a ringstand. Direct the blue flame toward the outside ofthe beaker. Gradually decrease the air intake. Theflame will deposit carbon only when the flame isyellow. In this case, there is not enough air intaketo completely burn the fuel.

Let the pupils investigate the nature of theblue flame.

Place a wooden splint across the barrel of aburner which is producing a blue flame. As thesplint starts to scorch, remove it from the flame,and study the pattern left on the splint. Comparethe result with scorch patterns produced when thesplint is held at different levels in the flame.Explain the reason for each pattern.

If the splint starts to burn, quickly removethe splint from the burner flame and extinguish thefire. The splint will always catch on fire at thetip of the blue cone. Point out that this area isthe hottest part of the flame.

REFERENCE OUTLINE

2. glassware - testtubes, beakers,flasks, bottles,graduated cylindersand funnels

J-12


Heat chemicals only when told todo so. Then carefully follow alldirections regarding the amount ofheat to use.

As a general rule, the rate of areaction increases rapidly with anincrease in temperature.

When using a bunsen burner, alwaysapply the heat gradually.

Glassware labeled Pyrex or fireresistant can be heated directly.However, one should apply the heat

, gradually to avoid unnecessaryextremes of temperature.

Most glass is a poor conductor ofheat and has a high degree ofexpansion as the temperatureincreases. As glass is heated itexpands unevenly since the glassdoes not have a uniform temperaturedue to its poor ability to conductheat. The uneven expansion causesstrains which make the glass breakor shatter when heated directly.However, glass may be heated in awater bath without breaking.

Pyrex or fire resistant glassexpands to a very small degree asit is heated. Therefore, it is notapt to break when direct heat isapplied gradually.

Bottles, funnels, and graduatedcylinders that are not Pyrex orfire resistant will shatter whensubject to the sudden change intemperature that occurs when directheat is applied.

3. porcelainware - Evaporating dishes should beevaporating dishes, placed on an asbestos gauze.-ormortars and pestles heated over a water bath.

Remove the heat source before allof the liquid has been evaporated.The contents may spatter if toomuch heat is applied. Keep the7q3fa:6e away from the dish.

J-15


KEY WORDS

REFERENCE OUTLINE

J-114


Mortars and pestles should neverbe heated or used for anythingexcept pulverizing solids. Somesolids explode upon being ground.

178

J-15


KEY WORDS

asbestosconductordirectionsevaporatingexpandspulverizingPyrexreactionresistsntshattertemperature

IDENTIFICATION OF EQUIPMENT

Have pupils examine and identify each of thefollowing pieces of equipment:

test tubestest tube holderstest tube rackclampsring standiron ringforcepstongswire gauze

179

clay trianglesbeakersflasksfunnelsevaporating dishesgraduated cylindersthistle tubesmortars and pestles

J-16

REFERENCE OUTLINE

4. assembling apparatus

a. cutting, firepolishing, andbending glass

(1) safety rule


Etching the glass with a fileproduces strains which reduce theforce (stress) required to breakor shear the material.

Newly cut glass tubes or rodsshould be fire polished to roundthe ends and reduce the possibilityof injury.

Glass becomes more fluid uponbeing heated. When fire polishingglass, hold the tubing at an angle,and rotate it so that gravity willnot cause the heated end to bendtoward the ground.

When bending glass, use a wing topon the burner since it is necessarytc have a larger amount of glassheated than in fire polishing.

Glass that has been heated in aflame cools slowly. Set the hotglass on an asbestos square tocool.

Do not let any one pick up glassthat has been heated until it hashad sufficient time to cool. Hotglass can cause very serious skinburns.

Discard any glass bend in whichthe bore has been pinched duringbending or fire polishing.

180

MATERIALS

KEY WORDS

etchingforceshearstrainsstresswing top

J-17

ACTIVITIES

GLASS TUBING

-

(a) Cutting glass tubing. At the desireddistance from one end of a length of glass tubingmake a deep scratch by drawing the file across theglass as it is held firmly on a flat surface. Holdthe tubing so that the cut is away from the body.Grasp the glass so that the thumbs are behind thescratch and the fingers are extended over the glass.Using the thumbs as a fulcrum, gently pull with thefirgers toward the body. The glass should breakeasily at the scratch mark.

If the scratch is not deep enough, a cleanbreak will not be made. The glass tubing may be held

in a towel to avoid injury to the hands and fingers.

After breaking the glass tubing, immediatelyfire polish the cut end.

(b) Fire polishing glass. The ends of glasstubing should always be fire polished.

Hold the tubing so that one end is justabove the blue cone of a burner. Rotate the glass,and remove it from the flame as soon as the endappears to be smooth. Too much heating may resultin the tube becoming sealed.

Caution pupils about touching hot glassas serious burns may occur. Do not allow more thanone pupil to heat glass in a burner at the same time.

181

REFERENCE OUTLINE

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J-19


(c) Bending glass. Fire polish the ends ofan 8-inch length of glass tubing. Now with a wingtop on the burner, hold the glass tubing lengthwiseabove the blue cone as shown in diagram a. Rotatethe tubing with both hands, and heat the centersection until it becomes soft and.pliable. Removethe glass from the flame and bend it to form a rightangle. If the hot glass is placed on an asbestossquare, the corner of the square can be used as aguide for making the bend. Discard any bend in whichthe glass bore has been pinched.

Emphasize the need for rotating the glasswith both hands while it is being heated. Demonstratewhat happens when the glass is held firmly in onehand and rotated with the other hand during theheating. The glass will coil up and can not be bent.

Compare glass bends made by using the bluecone of a burner with those made with a flame comingfrom the wing top. Note the bore of the tubing inthe bent part of each right angle bend. Ask thepupils to explain why the "wingtop" bend is

preferable.

KEY WORDS

J-20

REFERENCE OUTLINE MAJOR UNDERSTANDING ANDFUNDAMENTAL CONCEPTS

b. using delivery A thistle tube acts as a safety

and thistle device in a generator producing atubes gas. If any pressure should build

up, the liquid in the generatorwill be pushed up the thistle tube,and the pressure reduced. Unlessthe thistle tube allows for areduction of pressure, thegenerator may "blow up."

(1) safety rules Always wet both the glass and thestopper before trying to inserttubing into a stopper. The watepor glycerin used to wet the tubeacts as a lubricant.

II. Properties and changesin matter

Never push a glass thistle tube ortubing into a stopper. A twisting,turning motion should be used toinsert glass into the stopper.Pushing the glass may result In thetube snapping and glass beingpushed up through the palm of thehand.

Matter is anything that occupiesspace and has mass. Under theinfluence of gravity, mass hasweight.

Three clases of matter are ele-ments, compounds, and.mixtures.

Elements are not able to be brokendown into more simple substancesby ordinary chemical means, butmay be broken down into simplersubstances by nuclear reactions.

Most elements are classed as metals.

Compounds are composed of two or moreelements, chemically united, in adefinite proportion by weight.

Elements and compounds are often calledpure or homogeneous substances.

184

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KEY WORDS

J-22


Mixtures contain two or more sub-stances in varying amounts but theindividual substances can berecognized because they are notchemically united.

Mixtures are said to be heterogeneous

i8G

MATERIALS

gas collectingbottlesthistle tube2-hole rubberstopper

glass tubingmarble chipshydrochloric acidrubber hosepneumatic trough

KEY WORDS

chemically unitedcompoundselementsgeneratorhomogeneousheterogeneouslubricantmetalmixturesnuclearproportionspace

J-23

ACTIVITIES

Set up a gas generator as shown in the diagram.Use the apparatus to generate and collect carbondioxide. Show how to insert a thistle tube into a

stopper safely. Explain that the end needs to beunder the surface 6f the liquid so that the gas doesnot escape through the thistle tube. Place marblechips in the generator and slowly add dilute hydo-chloric acid. Show how to handle the bottle of acidand the stopper properly. Explain the reason forholding the stopper between the index and middlefingers.

Collect the gas in gas bottles that have beenfilled with water and inverted. In a vessel ofwater or a pneumatic trough insert the deliverytube under each bottle until it fills with gas.Test the gas by inserting a burning splint.

Exhibiting Matter

Ma'.e an exhibit of the different kinds of matter.Such a display might include the following:

Elementscoppersulfuraluminumironmercurytinzinc

Compoundswatercopper sulfatetable saltsandtable sugarmarble chips

187

Mixturescopper sulfate.andmarble chipssalt and sand orsawdust

muddy wateriron filings andchunks of roll sulfur

J-24


A. Physical properties All substances have specialphysical properties, e.g.;

_mass, weight, inertia, impenetrabilit2

1. Phases of matter The phase in which matter existsdepends upon how close together itsparticles are and how fast theymove.

a. solids

b. liquids

c. gases

When a change of phase occurs,energy is either absorbed orliberated.

Heat energy can be converted intokinetic energy of motion and/orpotential energy of position ofthe particles.

Kinetic and/or potential energy canbe converted into heat.

The particles of a solid arerelatively close together and moverelatively slowly.

The particles of a solid resist achange of position.

A solid has a definite shape andvolume.

The particles are farther apart andmove more rapidly in the liquidphace than in the solid phase.

Energy is absorbed when a solidliquefies and is released when a:Liquid becomes a solid.

A liquid takes the shape of thecontainer but has a definitevolume.

The particles are farther apartand move much faster in the gaseousphase than the particles in aliquid_or a solid.

J-25


KEY WORDS

189

REFERENCE OUTLINE

J-26


Energy is absorbed when a liquid- turns into the gaseous phase.Energy is liberated when the gascondenses into a liquid.

Gases have neither a definite shapenor a definite volume. They assumethe shape and volume of the container.

In the gasebus_ phase matter cangenerally be considered to bethe molecular form.

190

MATERIALS

KEY WORDS

absorbedconvertedenergygasheatinertiaimpenetrabilitykineticliberatedliquidliquefiesmassmattermolecularmotionphasepotentialsolid--weight

J-27

ACTIVITIES

PHASES OF MATTER

Use an.overhead projector to help develop theconcept of particle position and velocity in thephases of matter.

Obtain a supply of marbles and three clearplastic boxes of unequal sizes. Into the smallestbox put as many marbles as can be packed into asingle layer. Put an eaual number of marbles intoeach of the remaining boxes.

Set each box on the stage of the overheadprojector. Gently jiggle each box so that the marbles

move. Note the degree of movement and the distancebetween the marble particles in each case. Relatethe demonstration to particles in states of matter.

Best results for illustrating the gaseousphase can be obtained when the box is much largerthan that used to represent the other two phases.

11

EFERENCE OUTLINE

24' Other physicalproperties

J-28


Certain substances have specialcharacteristics of tenacity,ductility, malleability, elastic-ity, brittleness, hardness, andcolor. The properties vary indegree from substance to substance.

If a material resists being pulledapart, it has tenacity.

Malleable material can be beaten orrolled into thin sheets.

Ductile substances can be drawninto fine wires.

Brittle material tends to fractureunder shock or pressure.

Hard materials have the ability toscratch, etch, or cut othermaterials.

The color of a solid is the sameas the color of the light beingreflected from it.

B. Physical changes All matter can be changedphysically.

There is no change in compositionduring a physical change, but theremay be a change in form, phase, orenergy.

After a physical change has beenbrought about, the originalsubstance(s) involved in the changecan still be recognized by itsproperties.

MATERIALS.

hireWeights

(a) sheet copper

(b) piece of lead

(c) wire ofdifferentsizes andgauges

(d) heat sourcebobby pin orsubstitute

Moh's scalenail fileconper pennyglass

J-29

ACTIVITIES

TESTING TENSTLE STRENGTH

Illustrate the differences in tensile strengthbetween different metals. Use two wires of the samelength and diameter (No. 24 or 28 gauge). Supportthe wires from one end. Add weights until eachbreaks. The tensile strength varies directly withthe force needed to break the wire, and is a measureof the cohesive force between adjacent moleculesover the entire cross-sectional area.CAUTION: Be sure to wear safety goggles.

MALLEABILITY AND DUCTILITY OF SOME METALS

(a) Malleability of Copper. Demonstrate themalleability of copper. With a ball peen hammerpound a sheet of light-gauge copper into an ashtray.The wooden farm for ashtrays is usually availablefrom the art department or school shop.CAUTION: B sure to wear safety goggles.

(b) Malleability of Lead. With a ball peenhammer pound a lead fishing sinker into a "sheet."

(c) Ductility of Metals. Illustrate ductilityby passing around wires of different gauges andcomposition.

(d) Changing Ductility by Heating. Bend abobby pin back and forth several times to shcw its

ductility. It is difficult to break it by bendingand flexing. Heat the pin to redness in the bunsenflame and quench by plunging the pin into cold water.Tlne bobby pin is brittle now an,f_ can be broken easilyinto pieces.

TESTING HARDNESS

Ask pupils to look up in an earth science orgeology textbook the hardness scale used to testminerals. Then, using the hardness standards,determine the hardness of several materials. Includesome metals like copper, iron, and aluminum.

193

REFERENCE OUTLINE

J-30


J-31


If the hardness scale testing outfit is notavailable, some hardness ratings can be roughlyobtained by the following:Matter is s'cratched by a fingernail -

Hardness rating 1 - 2Matter is scratched by a copper penny -

Hardness rating 3 - 4Matter is scratched by a steel knife -

Hardness rating 5Matter scratches glass -

Hardness rating over 6

KEY WORDS

brittlenesscolorcompositionductilityelasticityformhardnessmalleabilityphasephysicalpropertiesreflectedsubstancetenacity

/95

J-32

REFERENCE OUTLINE MAJOR UNDERSTANDINGS ANDFUNDAMEMEUONCEPTS

1. Separating by A magnetic substance can be re-magnets 'moved from a mixture by means

magnet.of a

2. Dissolvingsubstances

Some substances are soluble;are not.

others

3. Filteringsuspensions

The degree of solubility of a sub-stance at different temperaturesmay be shown by a chart or grarh.

An insoluble substance can beseparated from a soluble one byfiltering. The insoluble materialis left on the filter paper. Thesoluble material is in the filtrate.

awastAlimini

MATERIALS

magnetiron filingscopper sulfateplastic bagfilter paper..funnelringring standwatch crystal orevaporating dish

KEY WORDS

filter paperfilteringfiltrateinsolublemagnetmagneticsoluble

J-33

AnTIVITIES

PHYSICAL CHANGES

In each of the following cases, pupils shouldobserve the original properties exhibited by thematerial and later explain why they know that aphysical change has occurred.

USING A MAGNET. Use a magnet to separate amixture of iron filings and copper sulfate crystals.Limestone, sodium chloride or any nonmagnetic sub-stance may be substituted the copper sulfate.

If a small plastic bag is slipped over the endof the magnet to be brought near the mixture, theiron will cling to the bag instead of the magnet.As the magnet is taken out of the bag, the ironfilings will drop off the bag.

FILTERING AND EVAPORATING. Add enough water toa mixture of copper sulfate and iron filings so thatthe copper sulfate is completely dissolved. Filterand evaporate the filtrate.

Marble chips or any insoluble substance may besubstituted for the iron filings in the mixture.

Demonstrate the method of folding and usingfilter paper. A piece of paper towel can be usedinstead of filter paper. If possible all pupilsshould have the opportunity to carry out thisactivity.

cri

13?

J-34


4 Evaporatingsolutions

Changing phase

A soluble substance can be re-covered from a solution by evapora-

tion.

A change of phase is a physicalchange since there is no changein the composition.

C. Chemical properties All substances have specialchemical properties.

1. Ability to reactwith

a. oxygen

Substances show varying degrees ofability to react with other sub-stances.

When substances combine withoxygen E d there is noticeablelight an heat given off, rapidoxidation or burning is occurring.

Some substances react with oxygenwithout any noticeable heat andlight being given off. Suchreactions are examples of slowoxidation.

b. water Some substances react with water.

c. an acid Some substances react with acids.

d. a base Some substances react with bases.

t.t:JS

MATERIALS

watch crystal orevaporating dish

heat sourcesodium chlorideWood's metaltest tube

KEY WORDS

acidlightoxidationreactsolution

J-35

ACTIVITIES

EVAPORATING SOLUTION

Assemble apparatus needed for evaporating asolution.

Recall the safety rules to be observed duringthe evaporation of a solution: Keep equipmentbeing heated at the back of the desk. Keep theface away from the work area.

Rapidly evaporate a saturated sodium chloride

solution. Call the pupils' attention to thespattering of the solid salt particles. Remindthe pupils that the salt particles are "boiling" hot.

Have pupils evaporate about 20 ml. of sodiumchloride or copper sulfate solution. Remind pupilsto remove the heat before all the liquid has beenevaporated to prevent possible decomposition of the

solid.

CHANGING PHASE. Melt a few grams of Wood'smetal in a Pyrex test tube. Pour the liquid metalinto a lightly greased dish or on the demonstrationdesk. Compare the properties of the alloy as itchanges from a liquid and back to a solid.

Wood's metal can be obtained from most chemical

supply houses.

VARYING DEGREES OF CHEMICAL ACTIVITY

TEACHER DEMONSTRATION ONLY. Show that elementsand compounds have varying degrees of chemicalactivity.

Using a copper strip, an iron nail, an aluminumstrip, a magnesium ribbon, calcium metal turnings,charcoal lumps, and copper sulfate crystals, demon-strate the following reactions and compare the

results. In no case use more than one small pieceof calcium turnings.

(a) Ability to Combine With Oxygen. Heat asmall piece of each substance in the oxidizing flame.Use long handle tongs to hold the substances as theyare heated. Note the rate of reaction.

Caution pupils not to look directly at the flamein which the object is being heated. Vigorous reac-tions, such as those with magnesium or calcium, canproduce harmful rays which may injure the eyes.

-1 9 9

J-36


J-37


(b) Ability to Combine With Water. Drop apiece of each substance into a few milliliters ofcold water. Note any evidence of a chemicalaction.

(c) Combining With an Acid. Put a tiny pieceof each substance into a few milliliters of dilutehydrochloric acid. Note any evidence of chemicalaction.

(d) Reacting With Bases. Add a tiny pieceof each material into a few milliliters of dilutesodium hydroxide solution.

(e) Comparing Results. Tabulate the resultsof each of the above reactions so that pupils maycompare the differing degree, if any, with whicheach substance reacts with oxygen, water, an acidand a base.

KEY WORDS

REFERENCE OUTLINE

D. Chemical changes

1. energy needed

a. heat

J-38

MAJCR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

Matter can be changed chemically.

Chemical change results in theformation of one or more mew sub-stances, each having its ownproperties by which :It is recog-nized. The properties of theoriginal material can no longer bedetected since the material nolonger exists.

Chemicals react according to edefinite combining ratio. If thecorrect ratio is not used, theexcess reagent will not combineand may be identified.

A chemical reaction involves aspecific amount of energy beforethe reaction can occur. The energymay be taken in or given off andmay be in such forms as heat, light,or electricity.

When heat is absorbed during achemical change, the action iscalled endothermic. Some or all ofthe products formed by endothermicreactions tend to be unstable andexplosive. Nitrogen compounds arein this class.

2 n

MATERIALS

sugarconcentratedsulfuric acid

beakertest tubemercuric oxideheat sourcecopper sulfaterock saltwashing sodaalum

KEY WORDS

chemical changecombining ratedefinitedetectedelectricityendothermicformationidentifiedoriginalreagentspecificunstable

j- 39

ACTIVITIES

Put four tablespoonfuls of ordinary sugarinto a 250-ml. beaker. Add sufficient concentratedsulfuric acid to thoroughly wet the sugar. Afterthe reaction occurs discuss the evidences of achemical change, including the heat produced by thereaction. Observe care in handling the sulfuricacid and in disposing of the black mass of porouscarbon that results.

Coverwithconcentratedsulfuric

acid

Demonstrate the decomposition of mercuricoxide by heating. Put about one-half teaspoonfulof mercuric oxide in a Pyrex test tube and heatwith a Bunsen burner. Use a test tube holder andclamp it next to the mouth of the tube. Call atten-tion to the little drops of mercury that form onthe sides of the tube. Test the gas produced witha glowing splint to show that it is oxygen.

Heat some dry copper sulfate (blue vitriol)crystals in a Pyrex test tube, supporting it so thatthe mouth is pointed slightly downward. Steam(water) is driven out as the crystals are heated.Heat the entire tube as uniformly as possible toprevent condensed water from running back andcracking the glass. Notice that the copper sulfatehPs lost its blue color and is almost white. Ifsome water is added to the white powder after ithas cooled, the blue color returns.

Repeat this procedure with some rock saltcrystals, washing soda, alum and other crystallinesubstances. Notice that some of these substancescontain water and others do not. This combinedwater is known as water of crystallization.

REFERENCE OUTLINE

b.edlectricity

J-40

MAJOR UNDERSTANDINGS PNDFUNDAMENTAL CONCEPT

MATERIALS

carbon rodsdry cellsbeakerwirecopper sulfatesolution

test tubeswaterdilute sulfuricacid

KEY WORDS

J-141

ACTIVITIES

Electricity is used in many ways to produce

chemical changes. Attach a carbon rod from anold dry cell or flashlight cell to the negativeterminal of a battery by means of a wire. Lowerthis rod into a beaker of copper sulfate solution.Connect a wire to the positive terminal of the celland place the opposite end in the solution. A

coating of copper will be deposited on the carbon.Metal objects may also be plated with copper inthis way.

Copper sulfatesoluhon

Carbonrod from ciry cell

Show that water can be taken apart by energyof electricity. Remove the carbon rods from twoold flashlight cells and connect these by means ofwires to four dry cells in series, as shown inthe diagram. Four half a test tube full of dilutesulfuric acid into half a glass of water. Filltwo test tubes with this solution and invert themover the carbon rods. Notice the bubbles of gasthat rise and collect in the tubes.

When the first tube is filled with gas, coverthe mouth with your thumb; remove the tube andreplace it with another. Test this gas with aburning splint. The gas is hydrogen, which ignites

when it combines with oxygen from the air. Noticethat water forms on the inside of the test tube.

f 5

J-42


-143


Test the gas in the other test tube, when itis full, with a glowing splint. The oxygen causesthe splint to burst into flame and burn brightly.Point out that two test tubes of hydrogren areproduced to every one of oxygen.

Note: Where available, a sou!-'ce of low volta,seD.C. current should be substituted fothe dry cell batteries.

KEY WORDS

J-1424


C. light

2. energy produced Heat, light, or electricity may beproduced by chemical action

a. heat

b. light

c. electricity

When heat is produced by a chemicalchange, the action is called exother-mic. The products formed by exother-mic reactions tend to be stable.

2n8

MATERIALS

matchescandlebeaker

KEY WORDS

exothermic

J-45

ACTIVITIES

LIGHT AND CHEMICAL CHANGE

Obtain_ a precipitate of silver chlorideby adding some dilute silver nitrate to sodiumchloride solution. Note the white color of thesilver chloride solid. Set the silver chloridein sunlight. Observe how the color changes overa period of time. The sun causes the silverchloride to decompose. Relate the activity tothe use of silver chloride in the film used incameras.

CAUTION. Silver nitrate makes a causticsolution which can cause serious burns. Use onlyvery dilute solutions and be careful not to getthe silver nitrate on the skin.

Light a candle and point out some of thephysical and chemical jcbanges that are takingplace. Emphasize the (role of heat in changingthe solid paraffin to aiquid, the capillary actionof the'wick, the change of the liquid to vapor andthe final chemical change as the vapor burns. Pointout that all liquid and solid fuels change to avapor before burning.

Hold a cold glass vessel over a candleflame so that moisture condenses upon it.

21)3

J.-46


MATERIALS

copper stripzinc stripwiregalvanometerwater (tap anddistilled)sodium chloridesugarvinegareyealcoholbaking sodatin stripsteel striplead stripaluminum strip

KEY WORDS

J-147

AnTIVITIES

Burn magnesium ribbon. (The light fromburning magnesium contains harmful ultra-violet rays. Do not look directly at anyvigorous reaction producing light.)

Cut a strip of copper about 8 cm. longand 11/4 to 2 cm. wide. Cut a similar strip ofzinc. Fasten a wire to each and connect thewires to a galvanometer. Touch the copper andzinc together. Observe that there is no indica-tion of an electric current. Dip the stripsinto a jar containing distilled water. Repeatthe procedure, using in succession, tap water, saltwater and solutions of other common substancessuch as sugar, baking soda, vinegar, lye andalcohol. Rinse in clean water after each trial.Make a list of solutions by ;1,1-,ich the gaivanometerindicates that a current is r,roduced.

Try two strips of other metals such as tin,steel, lead and aluminum. For one experimentuse two strips of the same metal. List theessential parts of a simple cell.

As a final step insert the strip of copper andthe strip of zinc into a lemon and observe theaction of the galvanometer. Use other fruitswhich contain acid and compare the results.

Golvonomel-er

Pil

Galvonorneher

ZincSoluhonsto be used

Lemon

REFERENCE OUTLINE

3. changing the rateof reaction

a. catalyst

b. concentration

J-148

MAJOR UNDETISTANDINGS ANDFUNDAMENTAL CONCEPTS

The rate at which a reaction occurscan be changed.

A catalyst is a substance which canchange the rate of a themicalaction without its own compositionbeing changed at the end of thereaction.

A catalyst may be any substancewhich acce!erates or deceleratesa chemical reaction. (Some catalyststemporarily enter into the reactionto form complex substances whichimmediately produce new substancesand release or reform the catalyst.Other catalysts do not directly enterthe reaction but collect gas moleculesto their surfaces. The gas moleculescoming into closer contact combinewith each other more rapidly.)

As the concentration of the mate-rials increases, the rate of thereaction generally increases andmay get cut of control. For thisreason use only small amounts ofreacting substances.

According to the law of mass action,tne reaction velocity variesdirectly with the product of theconcentration of the reactants.

MATERIALS

dilute solutionof sulfuric acid

beakercopper stripzinc stripvoltmeterwirebell/bvzzer

MATERIALS

hydrogen perox-ide (3%)

manganese di-oxide

splintgraduate

MATERIALS

sodium thio-sulfate

watergraduatebeakershydrochlortc acidlined paper

J-49

ACTIVITIES

Prepare a dilute solution of sulfuric acidby slowly adding one part acid to 10 parts ofwater in a Pyrex beaker, When the acid is coolput a fresh copper strip into the solution. Ob-serve that there is little evidence of chemicalaction. Next put a new strip of zinc into the

solution. Observe the formation of bubbles of agas which indicates that chemical change is takingplace. Also examine the surface of the 'inc afterit is removed from the acid.

Put both the copper and zinc strips into theacid and conne3t to a %roltmeter. Observe thevoltage and then connect the wires to an electricalbell or buzzer.

The explanation should be limited to the ideathat as a result of chemical action the zinc tendsto develop a negative charge (an excess of electrons)and the copper a positive charge (a scarcity ofelectrons). When connected by a conductor, electronsflow from the zinc to the copper.

USING A CATALYST IN A CHEMICAL CHANGE

Put 10 ml. of 3 per cent hydrogen peroxideinto a test tube. After a few minutes observe thebubbles which have appeared. Insert a glowingsplint into the mouth of the test tube and note thatlittle or no oxygen is given off.

Sprinkle about one-quarter teaspoonful ofmanganese dioxide into the hydrogen peroxide.Observe that the gas bubbles form faster. Testthe gas with a glowing splint.

The use of any hydrogen peroxide stronger than3 per cent is not recommended. The 3 per centhydrogen peroxide is the solution used as an anti-septic and may be obtained at drug stores.

EFFECT OF CONCENTRATION UPON VELOCITY OFREACTION

Make a solution containing approximately 10 gm.of sodium thiosulfate (hypo) in 100 ml. of solution.

J-50


J-51

MATERIALS ACTiVITIES

Into three 150-ml. beakers, place 10.0 ml.,5.0 ml., and 2.5 ml. of solution. In the secondand third beakers add 5.0 ml. and 7.5 ml. ofwater respectively so that each beaker contains10 ml. of solution. Place the beakers over asheet of lined papel, on a table

Add 10 ml. of hydrochloric acid (approxi-mately 1N) to each beaker. View the lines on thepaper by looking down through the solution. Whitecolloidal sulfur forms in eacb case. With a stopwatch determ:i.ne the times required for the mixtureto become opaque enough to make the lines invisible.Pretest the experiment and adjust the normality ofthe HC1 if the time of rilaotion is not satisfactory.

(Traces of poisonous sulfur dioxide may be

obLerved from this reaction. Be sure to have theroom well ventilated while the experiment is beingdone.)

KEY WORDS

acceleratecatalystcomplexconcentrationdeceleratelaw of mass actionrate

REFERENCE OUTLINE

c. temperature


As the temperature increases, therate of the reaction usually in-creases and may get out of control.For this reason, do not heat chem-icals unless told to do so. Thencarefully follow all directionsfor heating.

d. surface area The smaller the particles ofreactants are, the faster theycombine.

Many reactions are safely carriedout by using solutions of thereactants.

e. other factors There are other factors such aspressure of combining gases andthe nature of the reactants thataffect the rate of reaction.

21 G

MATERIALS

J-5 3

ACTIVITIES

EFFECT OF TEMPERATURE ON VELOCITY OFREACTION

Use the procedure listed in the previousactivity, but keep the volume of hypo constantat 10 ml. Vary the temperature of the hypo.Graph the results.

can with friction To get the varying temperature of hyno, bring

top some of the solution to a boil. As the sulutionfunnel cools, the desired quantities of hypo solutionrubber tube can be removed at different temperatures.candlelycopodium powder/ Cut a round hole in the bottom of a largecornstarch metal can having a friction top. Put a funnel

through the hole from the inside and attac:n arubber tube to it. Put a teaspcc4Iful of lyco-podium powder or cornstarch into the funnel. Seta lighted candle beside it and put on the cover.Attach the end of the rubber tube to a small airpump and blow a sharp blast of air into the can.A dust explosion results because the surraces ofmany particles of powder are in contact with theoxygen of the air and the flame spreads quickly.The lid of the can is blown off because of the rapidexpansion of air due to sudden heating.

steel woolasbestos padbunsen burneriron powdermagnesium ribboncopper strip

KEY WORDS

combining gasesnaturepressurereactants

Heat several different metals to illustratesome of the conditions which cause them to oxidize.Place some shreds of steel wool on an asbestospad and ignite them with a bunsen burner. Try toisnite solid pieces of iron. Sprinkle some ironpowder into a bunsen burner flame. Call attentionto the relation between the amount of surface ex-posed to the air and the ability of a metal to burn.

Hold a strip of magnesium ribbon and a stripof copper in the flame and compare the reactionsand the products.

REFERENCE OUTLINE

III.Introduction to AtomicStructure


Atoms occur singly as the smallestparticles of an element that canexist and still retain the physicaland chemical properties of theelement.

An atom consists of a nucleusaround which one or more electronsmay be found.

An atom can be considered to bemostly empty space.

For most practical purposes, theentire mass of an atom may beconsidered trl be in the nucleus.

There is no balance sensitive enoughto weigh an atom. The atomic weightis the weight of an atom as comparedwith the weight of a carbon atomtaken as 12 units.

The atomic weight of an atom is arelative weight in comparison tothe weight of an arbitrary standard.(Atomic weight is more properlycalled atomic mass.)

One standard is the 12.00000 unitstaken as the weight (mass) of thecarbon-12 isotope. Chemists andphysicists use this standard.

Another standard is the mass numberwhich is based upon the sum of thenucleons (protons and neutrons)each with a mass of one unit.Nuclear scientists use the massnumber standard.

A. Some Atomic Particles An atom contains protons, neutrons,and electrons.

1. nucleons The protons and neutrons areconcentrated in the central part ofan atom called the rucleus. Theyare called nucleons.

218

J-55


KEY WORDS

J-56


a. protons

(1) charge The proton carries a single positivecharge.

(2) mass The proton has a mass equal to oneunit.

(The mass of a proton or of aneutron is considered to be oneunit. An "isolated" proton actuallyhas a mass of 1.0081 units, and an"isolated" neutron has a mass of1.0087 units. However, when theprotons and neutrons make up anucleus, some of their masses havebeen converted into energy.)

J-57

MATERIALS

.

KEY WORDS

arbitraryatomatomic weightchargeelectronisolatedmass numberneutronnucleusnucleonpositiveprotonstandardstructure

ACTIVITIES

221

J--58


(3) atomic number The atomic number of an atomindicates the number of protons theatom contains. This is alao equalto the number of electrons in the

atom.

Each kind of element has its ownatomic number. No two elements canhave the same number of protons inthe nuclei of its atoms.

b. neutrons

(1) charge A neutron has no electrical charge;it is neutral.

(2) mass The neutron has a mass equal to oneunit.

(3) number of The number of neutrolls can be foundneutrons by subtracting the atomic number

from the mass number of the atom.

2. electrons

a. charge The electron has a s1ngle negativecharge.

b. mass

c. location in anatom

The mass of an electl,on is so smallin comparison to the mass of aproton that the mass of the electronis usually disregarded in detrmin-ing the mass of an atom.

The mass of the electron may beconsidered to be 1 of the mass

of the proton.

Electrons are located outside ofthe nucleus and are distributed inthe space which maKes up most ofthe atom.

In any atom there are as manyelectrons as protons.

222

J-59


KEY WORDS

atomic numbercomparisonnucleineutral

223

J-60


B. The Bohr atom

1. the nucleus

2. energy shells

Bohr's model of an atom is only oneof a numbJ:r of atomic models thathave been proposed.

There are more recent models ofatoms which help explain more aboutthe behavior of atoms than theBohr model can.

The Bohr model has been proved onlyas far as the hydrogen atom isconcerned.

The Bohr model serves quite well toillustrate atomic number, atomicweight, the principal valences, andmany chemical combinations of thefirst twenty elements.

The statements in this outlineconcerning the Bohr atom refer onlyto atoms with atomic numbers 1 - 20.Representations of atoms with atomicnumbers greater than 20 are compli-cated by exceptions to the simplerules stated.

The atomic number indicates thenumber of protons in the nucleus.(This is often represented by thesymbols, P or +.)

The difference between the massnumber and the atomic numberrepresents the number of neutronsIn the nucleus. (This is oftenrepresented by the symbol, N.)

The electrons are located outsideof the nucleus. Where they aredepends upon how much energy theyhave.

294

MATERIALS

KEY WORDS

Bohrenergy shellillustratesymbol

J-6 1

ACTIVITIES_

CONSTRUCTING ATOMIC MODELS

Using the chart below, pupils should be in-structed how to prepare atomic model diagrams.Reference should be made at this point to the useof the Periodic Table in supplying thegiven in the chart.

Atomic Atomic

Number Element Symbol Weight Protons Neutrons

information

ElectronArrangement

1 Hydrogen H 1 1 0 1

2 Helium He 4 2 2 2

3 Lithium Li 7 3 4 2,1

4 Beryllium Be 9 4 5 2,2

5 Boron B 11 5 6 2,3

6 Carbon C 12 6 6 2,4

78

NitrogenOxygen

N0

1416

78

78

2,52,6

9 FLuorine F 19 9 10 2,7

10 Neon Ne 20 10 10 2,8

11 Sodium Na 23 11 12 2,8,1

12 Magnesium Mg 24 12 12 2,8,2

13 Al(Aninum Al 27 13 14 2,8,3

14 Silicon Si 28 14 14 2,8,4

15 Phosphorus P 31 15 16 2,8,5

16 Sulfur S 32 16 16 2,8,6

17 Chlorine Cl 35 17 18 2,8,7

18 Argon Ar 40 18 22 2,8,8

19 Potassium K 39 19 20 2,8,8,1

20 Calcium Ca 40 20 20 2,8,8,2

Although the pupil should realize that theprobable arrangement of the electrons is thl'ee-dimensional and rather vague, the two-dimensionaldiagram is generally satisfactory for elementaryexplanations and is easier to draw.

In order to prevent misinterpretation due tovague or crowded diagrams, a relative2y uniformsystem of representation should be used. It issuggested that acceptable diagrams include thefollowing features.

A title beneath eacn diagram ..--------,//,-------, ''.,

, ,/ / ----,

.

\ \/ ', \

The nucleus represented as a i r , \ ,

,

circle at least i inch in, ,

1 ,

diameter 1 ; 12N/?

t , \,

\ \ "... ..' i /\ s. ---- // %

\ '-----

Socii-u-r;,--;11-om

such as "Sodium Atom"

In the nucleus the numbers ofprotons and neutrons clearlyindicated by number and codesuch as protons (11+ or 11P)and neutrons (12N)

J-62


J-63


The completed inner shells represented by dashed

arcs or circles about 1/4 inch apart with numbers

placed on each arc or circle to represent the

number of electros in eanh completed shell

The outer (valence) shell represented by adashed circle with a radius about 1/4 inch larger

than the radius of the preceding arc and elec-

trons in the valence shell clearly shown assolid cficles or by "e"

(a) Draw circles on a large sheet of paper. Paste

or fasten the paper on tackboard or heavy cardboard.

Use thumbtacks of three colors to represent the

particles.

(b) For use with an overhead projector draw circles

on a sheet of clear acetate with acetate-type ink(available in art stores). With a paper punch, punchout the particles from pieces of colored acetate orcellophane. Static electricity helps hold the

particles in position. The entire set may be con-veniently stored in an envelope.

KEY WORDS

J-64


In the Bohr model electrons areconsidered to revolve around thenucleus in one of several concen-tric circular orbits.

In newer models of the atoms, theorbits (energy levels) are neitherconcentric nor always circular.

The orbits are called shells orrings and can be denoted by theletters K, L, M, N, 0, F, or bythe numbers 1, 2, 3, 4, 5, 6.

Electrons in orbits near thenucleus have less energy thanthose in orbits farther from thenucleus.

Electrons may be raised to ahigher energy level by the additionof energy. When the electron dropsback to a lower level, the energywhich it has absorbed is releasedin the form of light. Thisaccounts for the different coloredflames which are produced whencertain substances burn or areheated to incandescence.

2)6'

MATERIALS

KEY WORDS

concentricenergy levelincandescenceorbitrevolverings

J-65

ACTIVITIES

TEACHER NOTE:

(The quantum-wave mechanics model ofthe atom is-beyond the depth and backgroundof most general science pupils. Teachersshould be interested in this newer modelsince it gives more useful information thanthe Bohr atom. College and some high schoolchemistry textbooks describe this model indetail.)

J-66


a. electrondistribution

(1) K-shell

(2) L-shell

There is a maximum-number ofelectrons which each orbit canhold.

The first (K) shell can hold nomore than two electrom.

The second (L) shell can hold nomore than eight electrons.

Atoms with atomic numbers 1 - 20can have no more than eight elec-trons in the third (M) shell.

b. classification Elements may be classified asof elements metals, nonmetals, or inert elements

depending on the number of elec-trons in the outermost shell.

(1) metals Atoms with 1, 2, or 3 electrons inthe outermost shell are classifiedas metals. They will react withnonmetallic atoms.

(2) nonmetals Atoms with 5, 6, or 7 electrons inthe outermost shell are classifiedas nonmetals and they will reactwith metallic atoms.

(3) metalloids Some elements with 3, 4, or 5electrons in the outermost ring mayhave properties of both metalsand nonmetals. (These shouldproh9_bly not be discussed as a classtopic at this point in the study ofchemistry.)

(4) inert elements Atoms with full outside shells areclassified as inert elements sincethey seldom enter into any chem-ical action.

230

J-67


KEY WORDS

classificationdistributioninertmetalloidsnon-metals

REFERENCE OUTLINE

J-68


c. chemical action The number of electrons in theoutermost shell determines the wayin which an atom will react chem-ically.

During chemical action, the atomsof metals and nonmetals try toform complete outer rings in whichcondition they are the most stable.

Metals tend to lend all of theelectrons in the last"shell inorder that a completed outermostshell remains.

Nonmetals tend to borrow electronsin sufficient quantities to bringthe electron number to the maximumamount for the outside ring. Theparticle gets ring completeness.

When an atom either borrows orlends electrons, it becomes acharged particle (ion) because thenumber of electrons no longerequals the number of protons.

There are always two oppositelycharged kinds of ions formed duringthe lending and borrowing of elec-trons. The two particles arrangethemselves in such a manner thatthey form a new compound. A loss ofan electron produces a positivelycharged ion, while the gain of anelectron produces a negativelycharged ion.

A deficiency of electrons (s) isnoted by a plus sign; an excess ofelectrons (s) by a minus sign.

In the solid state the ions assumedefinite positions in a crystallattice. The oppositely chargedparticles are held in place byelectrostatic attraction.

J-69


KEY WORDS

attractionborrowchemical actionchemicallycrystal latticedeficiencyelectrostatic

lendsufficient

REPRESENTING A CHEMICAL CHANGE WITH ATOMICMODEL DIAGRAMS

In diagraming the probable structure of ioniccompounds, use an arrow to show the shifting of avalence electron to its new position. The shiftingelectron(s) may be shown as solid circles in theoriginal position and as open circles in the newposition.

/

I/// \

/ / 17+ ;

/ \\ \

18N / TI , ,/ y/

Formation of Sodium Chloride

213

J-70

MAJOR UNDEPSTANDINGS ANDFUNDAMENTAL CONCEPTS

The value of the periodic tablelieS in its usefulness toscientists and others who studychemistry.

Early periodic tables based uponatomic weights led to predictionsof properties of elements that werenot known at the time. Thesepredictions led to the discoveryof many elements.

The periodic table is used toorganize and classify a large bodyof information about the elements.

The elements in the modern periodictable are arranged according toincreasing atomic numbers in sucha way that similarity is shown be-tween numbers of shells and numbersof electrons in the outermost shells.

Before the table can be read cor-rectly, its key must be understood.

The key shows the symbol of an ele-ment, its atomic number, and itsatomic mass (weight). (Any referencetable may have a key and the tablecannot be correctly used until thekey is understood.)

Since isotopes in different con-centrations may be present withina sample of an element, any deter-mination of atomic weight mayrepresent an average rather than aspecific atomic weight. The massnumber of the most common isotopeof the element can be usuallyobtained by rounding off the atomicweight to the nearest whole number.

2 4

MATERIALS

I A

2

3

7Li

3

23No

11

J-71

ACTIVITY

THE PERIODIC TABLE

II A10

Be424

Mg12

Trace the outline and boxes of the periodictable shown. Transfer the "skeleton" to a stencil

or ditto master, and duplicate enough copies sothat each pupil may have one. Refer to theactivity on page J-61 for the electron arrangementof the first 20 elements.

Atomic Mass(Approximate atomic weight)

Atomic Numbex

Key

8

III B IV B VB V1B VII B IE. II B

39

19

40Ca

20

Groups 14! He

III A IV A V A VI A VII A 2

11

5

27AI

13

12

628

Si14

14 16 190 F

7 8 9

31 32 35

15 10 17CI

20Ne

1040

Ar18

KEY WORDS

averageclassifyisotopekeyorganizeperiodic tablepredictionrounding-offwhole number

Lanphsnide Series Elements 58 through 71

Actinide Series Elements 90 through 103

235

J-72


J-73


Have the pupils number the periods and groupsand mark the zig-zag line running from boron to thebottom of period 6. With a crayon or coloredpencil shade in the area between the period numbersand the zig-zag line. Label the area metals. Thearea between the zig-zag line and group 0 shouldbe shaded with another color and be labeled non-metals. A third color may be used to tint group 0which is labeled inert gases.

KEY WORDS

Name several elements and ask the pupils touse the periodic table to determine whether theelements are metaalic, nonmetallic, or inert gases.

2.-37

REFERENCE OUTLINE

3. arrangement

a. groups

b. periods

4. use of table

a. predictingproperties ofelements

J-714


The elements are arranged incolumns and rows. The columnsgoing down the table are calledgroups. The rows going across thetable are called periods.

Groups contain elements which havesimilar chemical properties.

Elements within a group have thesame number of electrons in theoutermost shell.

Some gy!oups have special names suchas group 7A which is known as thehalogens and IA as the alkalimetals.

The horizontal rows are calledperiods. Each period contains allthe elements which have the samenumber of electron shells.

Scmetimes a period is called aseries.

The period number corresponds tothe number of shells or orbits.

The location of an element on thetable generally indicates the typeof element it is. Knowing thetype of element, one can expect theelement to have chemical propertiessimilar to the other elements ofthe same group.

J-75

MATERIALS

KEY WORDS

ACTIVITY

2-39

J-76


(1) metals

(2) nonmetals

Elements found left of the heavyblack line, which runs step-wisefrom boron (B) to the bottom ofperiod 6, are generally classifiedas metals.

More elements are classified asmetals than as nonmetals.

Elements between the heavy blackline and group 0 are classified asnonmetals.

24:0

J-77


KEY WORDS

Alkalifamiliesgroupshalogensperiodsseries

J-78

Rt,FERENCE OUTLINE MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

(3) metalloids Elements found along this line areclassified as metalloids for theyexhibit both metallic and non-metallic properties. These ele-.ments act as the "turning point"within groups such as 5A and 6Awhich contain typical nonmetals atthe top and metals at the bottomof the group.

(4) inert elements Elements in group 0 constitute a(rare gases) special group which do not readily

react. They are called noblegases, rare gases, or inert gases.

b. predictingactivity ofelements

(1) metals

(2) nonmetals

Members of group 0 are unique inthat they are the only elements tohave both electrical balance (equalnumber of protons and electrons)and a full electron load in theoutermost orbit.

Other atoms have electrical balancebut do not have a full electronload in the outside orbit. Whenthese atoms react, they tend tocomplete the outer orbit in someway.

Metals usually react because theylend electrons. In those metalswhose outer electrohs are furthestfrom the nucleus, the outermostelectrons are attracted least by thenucleus and are most easily lost.Therefore, the metals at the bottomof the table are tha most active.

When nonmetals react with metals,the nonmetals gain electrons. Inthose nonmetals whose outer elec-trons are nearest the nucleus,additional electrons are attractedto the nucleus most easily. There-fore, the nonmetals at the top ofthe table react most easily withmetals.

242

J-79


KEY WORDS

chemical balanceelectrical balanceinert gasesmetallicnoble gasesnon-metalrare gases

243

REFERENCE OUTLINE

IV. Common chemicalchanges

A. Reacting substances

1. two elementscombining to forma single compound

a. product formed

J-80


A chemical change produces one ormore new substances, each havirmits own set of properties by whichit can be recognized.

Two substances may react to formone or more new substances. Theproducts formed depend upon thenature of the reacting substances.

Two elements may combine to form asingle compound.

A metal combines with a nonmetal toform a compound known as a salt.The metallic atoms lend electronsto the nonmetallic atoms during thereaction.

A nonmetal may combine with anothernonmetal. Electrons are not loanedbut are shared by both kinds ofatoms. Carbon dioxide, sulfurdioxide, and the oxides of nitrogenare examples of compounds formedby two nonmetals sharing electronsin covalent bonding.

Oxygen unites with most elements toform oxides.

There are instances where a metalwill combine with another metal.During the formation of an alloy,s-ome metals combine. Someexamples are copper and tin formingCuSn and copper and aluminumforming CuAl

2.

MATERIALS

asbestos sheetzincsulfurbunsen burner

magnetringstandclampstest tubeiron powder(filings)

sulfurheat source

KEY WORDS

alloychemical com-bination

J-81

Asbestossheet-

-

ACTIVITIES

Mixture ofzinc and sulfur

The chemical union of a metal and a nonmetalis shown effectively by the reaction between zincand sulfur. Mix a pinch of powdered zinc with apinch of powdered sulfur and place the mixture inthe middle of a large asbestos pad. Ignite themixture with a bunsen burner flame after makingsure that pupils are at a safe distance from thedesk. Discuss the evidences of a chemical changeand develop the word equation for the reaction.

Mix 7 gm. of iron powder or iron filings and5 gm. of powdered sulfur. Test the mixture with amagnet and point out that the iron and sulfur maybe separated in the mixture. Pour the mixture intoa Pyrex test tube and support the test tube in aclamp on a ringstand. Heat the mixture gentl:y atfirst and then strongly. Keep the flame in uotionso as to heat the tube uniformly. When the contentsof the tube begin to glow, remove the heat and callattention to the evidence

Iron andsulfur

4agnet

Iron SulfurIron

sulfide

161111130111.Original mixl-ure Newcompound

of a chemical change. When the tube is cool, wrap itin a piece of cloth and break it with a hammer. Testthe mass with a magnet to show that a new nonmagneticsubstance, iron sulfide, has been formed.

245

EFERENCE OUTLINE

b. naming theproduct

2. an element and acompound reacting

J-82

MAJOR UNDERSTANDINGS ANUFUNDAMENTAL ::ONCEPTS

If a compound is composed of only ametal and a nonmetal, the name ofthe compound contains two parts.The first part is the name of thz)metal; the second is the name ofthe other element with its nameending changed from-ine or -en toide. (Examples - chloride, oxide)

Compounds ending with the letfes-ite or -ate contain thre or moreelements, one of which is oxygen.

In some chemical reactions, one ofthe elements in a comnound replacesanother element.

When a metal and a compound con-taining a metal react, the metalreplaces the metal in the compoundand a different compound is formed.

When a nonmetal and a compoundcontaining a metal react, the non-metal may replace the nonmetal inthe compound and a differentcompound is formed.

243

4ATERIALS

Deakercopper sulfatesolutioniron nails

test tubesevaporating dishsplintsheat sourcecopperzincironaluminumdilute hydro-chloric acid

KEY WORDS

chemical re-placement

J-83

ACTIVITIES

TEACHER NOTE:

It is not advisable at this level to considerany situation in which a metal replaces a nonmetal.

Although hydrogen may be classed as a nonmetal,it is advisable at this level to consider it as ametal since it has many chemical properties similarto those of a metal.

Drop a few iron nails into a beaker containingcopper sulfate solution. After a short time removethe nails and dry them with a soft cloth. Pass thenails around the class and ask for explanations of

the chemical change.

Develop the idea that some metals are able todisplace other metals from certain compounds insolution.

Demonstrate that some metals are able to displacehydrogen from acids. Put pieces of zinc, iron, alumi-

num and copper in four separate test tubes in a rack.

Burningsplini-

Copper AluminumZinc Iron

Infraredlamp

Add an equal amount of dilute hydrochloric acid to

each. Observe the reaction in each tube and testthe gas produced with a burning splint. Develop aword equation for the reaction.

Since pupils will not see evidence of the saltformed, filter the solution from one test tube inwhich a reaction has taken place and evaporate thedissolved salt to dryness.

24 7'

j-814

REFERENCE OUTLINE MAJOR UNDERSTANDINGS ANDFUNDAMENTAL-MMEPTS

24 B

J-85


An effective way to evaporate a solution isshown in the diagram. An infrared lamp is supportedas shown and the material being evaporated is pouredinto a watch glass or evaporating dish and placed afew inches below the lamp.

KEY WORDS

USING AN OVERHEAD PROJECTOR TO SHOW REACTIONS

Many interesting details of the reaction betweenan element and a metallic compound can be observedwhen they are projected on a screen by an overheadprojector.

Silver Trees. Put some silver nitrate solutionin a petri dish set on the stage of an overheadprojector. Drop a length of copper turning or wireinto the solution. After a few minutes a silver"tree" will grow and a blue copper nitrate area willappear around the "tree." The speed with which the"tree" grows depends upon the concentration of thesilver nitrate solution.

Similar trees can be grown from zinc, magnesium,or lead placed in a silver nitrate solution. Therate of growth will vary with the activity of themetal. Since the nitrates of these metals makecolorless solution, no color will appear aroundthe trees.

24

REFERENCE OUTLINE

a. activity of

J-86


Each element has its own degree of

elements chemical activity.

b. predicting thereaction

An element can replace only thoseelements which have a lower degreeof activity than it has.

An element in a compound can bereplaced by any element more activethan it is.

The elements may be listed accordingto their degrees of activity. Thelist is called an activity orelectrochemical series. Theactivity series may be used topredict whether an element and acompound will react.

The most active metals are found atthe top of the series.

A metal can replace any metal listedbelow it in the activity series.

Me most active nonmetal is foundat the bottom of the activityseries.

',A nonmetal can replace only thosenonmetals listed above it in theelectrochemical series.

9 n4- ,j

MATERIALS

KEY WORDS

activityactivity serieschemical re-placementsouble re-placementelectrochemicalseries

simple re-placement

J-87

ACTIVITIES

REACTION RATE VARIES WITH THE ACTIVITY OFA METAL

Place tw..) petri dishes on the overhead pro-jector, and into each dish pour the same amountof dilute hydrochlo'fic acid. Simultaneouslydrop a small piece of zinc into one dish and asmall piece of magnesium into the other dish.Compare the size and number of gas bubbles thatare formed. (If the metal is tarnished, it shouldbe cleaned before adding it to the acid.)

Other combinations of metals may be used.Copper wi 1 not react with the acid. Relate itsbehavior the activity series.

SINGLE REPLACEMENT REACTIONS

Give each pppil a piece of copper, zinc, lead,and iron nails. Also have available the followingsolutions: silver nitrate (2 grams/liter), coppersulfate, ferrous (iron) chloride, and sodiumchloride.

Instruct the pupils to place a clean piece ofone of the metals into 5 to 10 ml. of any one ofthe solutions in a test tube. After five minutesobserve the metal and note any formation of adeposit or change in the color of the solution.Identify the products by writirg a word equation.Check the activity chart shown below to determineif the reaction should occur.

ACTIVITY SERIES

Metals

(K) Potassium(Ca) Calcium(No) Sodium(Mg) Magnesium(Al) Aluminum(Zn) Zinc(Fe) Iron(Ni) Nickel(Sn) Tin(Pb) Lead(H) Hydrogen(Cu) Copper(Hg) Mercury(Ag) Silver(Au) Gold

5_1

Nonmetals

(F) Fluorine(C1) Chlorine(Br) Bromine(I) Iodine

J-88

Iv, A_JOR UNDERSTANDINGS AND

FUNDAMENTAL OUNCEPTS

J-89


(A complete electrochemicalseries includes the nonmetals.In this case the most activenonmetal appears at the bottomof the chart.

KEY WORDS

The nonmetals are sometimeslisted in a separate activitylist with the most active non-metal at the top of the list.)

For example, if iron and copper sulfate areplaced together, there will be a reaction which formsiron sulfate and copper. Iron is more active thanthe copper and replaces the copper. If, however,copper and ferrous(iron) chloride are placed to-gether, no reaction will occur since copper is lessactive than iron.

Pupils may repeat the procedure using differentcombinations of metal and solution. UNDER NO CIR-CUMSTANCES shoula pupils be given potassium, cal-cium, or sodium for any laboratory activity. Re-quire the identification of products to discouragepupils "playing" with chemicals.

253

J-90

REFERENCE OUTLINE MAJOR UNDERSTANDINGS ANDRUNDAMENTAL CONCEPTS

Two compounds may react to formone or more compounds.

3. two compoundsreacting to formtwo compounds

a. precipitation

Usually two compounds exchangeparts to produce two new compounds.

When the solutions of two compoundsare combined, one or both of theproducts formed may be insoluble.

A precipitate is an insoluble sub-stance formed during the :ceactionbetween two solutions.

(1) solubility A solubility table tells the degreetable of solubility of many substances.

(2) predictingprecipitation

A substance can be described assoluble, slightly soluble, orinsoluble.

Actually any sOpstance will dis-solve to some extent in water. If,however, only a trace dissolves, itis said to be insoluble.

The table of solubilities can beused to predict if a precipitatewill be formed during a reactionbetween two solutions.

After determining the possibleproducts, use the solubility tableto see if either product is insol-able. An insoluble product willappear as a precipitate and can beseparated from the remaining solu-tion by filtration.

3. Decomposition A single substance may break up toform more then one substance.

MATERIALS

KEY WORDS

chemicai tie-composition

exchangeinsolubleprecipitatesolublesolubility table

J-91

ACTIVITIES

PREPARING PRECIPITATES BY REACTING TWO COMPOUNDS

Make solutions of various compounds such ascopper sulfate, barium chloride, potassium iodide,sodium bromide, aluminum sulfate, potassium di-chromate, iron II (ferrous) sulfate, silvernitrate (2 grams/liter), and sodium hydroxide(4 grams/liter).

Tell the pupils that they can combine any ofthe solutions they wish as long as they do not usemore than 5 ml. of any solution and use no morethan twc> solutions at a time.

Require the identification of the precipitate.Pupils should write a word equation and then checkthe solubility of each product by referring to atable of solubilities. Mo-e advanced pupils mayrefer to a handbook for solubility of any substancenot listed on the table of solubilities in thetextbook.

TEACHER NOTE:

Pupils can predict the products to be formedby writing a word equation. Have the pupils drawa line between the two parts of each compound'sname. The two "ends" combine and the two "middle"ones combine. Remind the pupils that the metal'sname is always first in the name of the compoundformed.

REFERENCE OUTLINE

J-92


J-93


mercuric oxidetest tubesheat sourcesplints

Many new substances are produced by chemicalchanges in which compounds are "taken apart." The

Carefullytransfer to

I Place mercuric test tubej oxide on foldedI filter paper

.kGlowinqsplint

bursts inoflame

Mercurydroplets

Heal-vigorously

heating of mercuric oxide may be repeated withemphasis on the chemical change that occurs duringthe decomposition of the compound.

Demonstrate the proper way to transfer themercuric oxide to the test tube without getting iton the sides of the tube. Heat to a high degreethe lower part of the tube but keep it movingslightly as it is held in the flame. Call attentionto the mercury deposit on the cooler portions ofthe tube and use a glowing splint to show the presenceof oxygen. Develop the word equation to representthe chemical change.

REFERENCE OUTLINE

1. formation of twoelements

J-94


Compounds containing only two ele-ments may decompose to form a metaland a nonmetal.

Compounds containing more than twoelements may decompose to form newcompounds or an element and acompound.

2. formation of other Some substances decompose to form

compounds one or more compounds.

3. use of energy The energy lost during the formationof the compound must be restoredduring the decomposition process,therefore, decomposition reactionsusually require energy in the formof light, heat, or electricity.

C. Chemical symbols Symbols are used to represent ele-ments and quantities of elements.

1. representing a A chemical symbol stands for the

name .

name of a specific element.

A symbol is a contraction of a nameof an element. The symbol mayconsist of a single capital letteror two letters, the first of whichis always a capital letter and theother letter is always a smallletter.

258'

MATERIALS

hydrogen peroxidetest tubesplintsbunsen burner

test tubesHoffman apparatus

KEY WORDS

contractionsymbol

0.-95

ACTIVITIES

Pour some hydrogen peroxide into a test tubeand heat it gently. Insert a glowing splint intothe mouth of the test tube and note that little orno oxygen is given off.

Now add a little manganese dioxide and againheat the contents gently. Test with a glowingsplint to show that oxygen is being liberated.Mention that the manganese dioxide is a catalystand accelerates the decomposition of the hydrogenperoxide.

Glowingno Flame

6

Addmanganese

dioxide4 5plinl-

bursl-sinl-o flame

0_--' Hydrogenperoxide

1V

Water can be "taken apart" by an electriccurrent. If a commercial Hoffman apparatus isavailable, it can be used to show the exact volumerelation of the two gases produced, the extremelysmall amount of water that is decomposed andthe slow burning of hydrogen at the jet.

* LEARNING SOME OF THE MOST FREQUENTLY USED SYMBOLS

Pupils should learn the following symbols whichare most frequently used in the science laboratory.

aluminum Alcalcium Cachlorine Clcopper Cuhydrogeniodinemagnesium Mgmercury Hg

nitrogenoxygenphosphorouspotassiumsulfurtinuraniumzinc

0

Sn

Zn

*Learning occurs best through association and use than throughrote memorization.

J-96


J-97


NAMING ELEMENTS

For enrichment have somc pupils do libraryresearch to find how elements were named. Includein the list of elements the following: polonium,germanium, francium, americium, europium, einstein-ium, fermium, indium, mendelevium, oxygen, plutonium,uranium, neptunium, curium, and helium. Ask thepupils to find why the symbol for tungsten is W.

Similarly, why the symbol for:

Iron is Fe

Silver is Ag

Gold is Au

Sodium is Na

Mercury is Hg

KEY WORDS

REFERENCE OUTLINE

2. representing aquantity

a. subscripts

J-98


Some symbol ',.re derived from theLatin names for the elements, e.g.;silver - Ag (Argentum), iron - Fe(Ferrum), lead - Pb (Plumbum),sodium - Na (Natrium), potassium - K(Kallium), gold 7 Au (Aurtm), etc.

A symbol stands.for one atom of anelement.

A subscript placed after and slightlybelow a symbol indicates that thereis more than one atom of the element.The number of atoms ecuals the numer-ical value of the subscript.

When a subscript is not writtenafter a symbol, it 1$ understoodthat the subscript is 1.

Cl mean 2 atoms of chlorine. H C2 2'

means 2 atoms of hydrognn and oneatom of oxygen. However, H 0 is

2 2

an entirely different substancesince it has two atoms of hydrogenand two atoms of oxygen.

CO has 1 carbon atom and 1 oxygenatom but is not the same substanceas CO which has 1 carbon atom and

2

2 oxygen atoms.

Other examples that might be usedare H , N , 0 , NH , C H , CH , and

2 2 2 3 6 6 4

NO .

2

J-99


USING SYMBOLS TO REPRESENT THE COMPOSITIONOF COMPOUNDS

KEY WORDS

numerlcalsubscript

Select a few substances that have been usedand display- each one in a reagent bottle which bearsthe formula for the substance. Provide also a listof elements and their symbols. Ask the pupiIs toname the elements represented by the symbols ineach formula and to give the number of atoms ofeach element as shown by subscripts.

TEACHER NOTE:

(Avoid using the formula for any ionic com-pound such as a salt. The formula indicates aratio of ions in the crystal lattice, not theformula f-J-17 a single molecule. Limit examplesto formulas for gases or raolecular compoundssuch as benzene (C6H6), methane (CH ) or

octane (C H ),)8 18

2:ci3

REFERENCE OUTLINE

b. brackets orparenthesis

c. coefficients


If a group of symbols are enclosedwithin brackets or parenthesis,each symbol is multiplied by thesubscript following the bracketsor parenthesis.

A number preceding a symbol or agroup of symbols is called a co-efficient.

A coefficient acts as a multiplierfor all of the symbols followingit in the compound.

Coefficients are often used inchemical equations.

Coefficients are usually found inan equation which is a chemicalshorthand for expressing the amountand kinds of combining materialsand products formed during a chem-ical action.

2C0 means 2 carbon and 2 oxygenatoms.

2 CO means 2 carbon and 2 x 2 or2

4 oxygen atoms.

2lig0-4 2 Hg + 02states that two

groups each consisting of 1 mercuryatom and 1 oxygen atom forms(decomposes) 2 mercur.i7 atoms and 2

oxygen atoms. The different kindof atoms are no longer chemicallycombined.

2Hg0.4 2 Hg 02 can also be read:

2 moles of merr;uric oxide decomposeto yield 2 moles of mercury and 1

mole of oxygen.

ps

J-101

MATERIALS

KEY WORDS

ACTIVITIES

2G5

!IFERENCE OUTLINE MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

Common compounds andmixtures

A. Compounds A compound contains two or moreelements chemically united.

A compound has properties unlikeits individual component parts; itis a homogeneous substance.

J-103


For enrichment the most capable pupilsmay be taught formula and equation writing.Consult a chemistry textbook for details.

KEY WORDS

bracketscoefficientsequationexpressingformulamolesmultiplierparenthesis

REFERENCE OUTLINE

*1. weight ofcomponents

2. separation ofcompounds

3. classes ofcompounds

a. acids

*optional

J-1014


*Elements making up a compound havebeen united according to a definiteproportion by weight.

One way of finding the combiningratio uses the correct formula fora compound. Multiply the subscriotby the atomic mass (weight) of eachelement. Set the values obtainedin ratio form and reduce the ratioto its simplest value. Then set upthe proportion, but be sure to keepthe order consistent.

Example: H 02

weight of hydrogen = 2 x 1 = 2

weight of oxygen = 1 x 16 = 16

The ratio of 2:16 reduces to 1:8;therefore,

weight of hydrogen 1

weight of oxygen 7

The component parts of a compoundcan be separated by a chemicalchange.

A compound may be an acid, a base,or a salt.

The properties of a compound deter-mine if it is an acid.

Acids turn litmus red.

Acids neutralize the effect ofbases.

AcidS combine with many metals.

2 c'

MATERIALS

dilute hydro-chloric acid

watergraduatetest tubeszincmagnesiumcopperironsplintsdilute sulfuricacid

KEY WORDS

acidbaselitmussalt

J-105

ACTIVITIES

ACIDS COMBINE WITH SOME METALS

Before classtime prepare a quantity of dilute

hydrochloric acid. Slowly pour, while stirring,a given quantity of concentrated acid into three

times its volume of water. Plan on 50 ml. ofdilute acid Der pupil.

To calculate the volume of acid needed for aclass, multiply the number of pupils by 12.5 ml.

of acid. Add this acid to three times as much water.

(Before they start the exercise, instructpupils to put baking soda on any acid spilled onthe desk to neutralize the acid. A box of baking-soda may be kept on each laboratory desk for such

emergencies. Acid or base spilled on the skin

should be washed off immediately with quantitiesof water.)

Label four test tubes 1, 2, 3, and 4. Put apiece of zinc in number 1, a 1-2-inch strip of mag-nesium ribbon in number 2, copper in number 3, andan iron nail in number 4. Pour 10 ml. of the di-luted hydrochloric acid into each tube and note therelative speeds of the reactions. Test the gasformed by bringing a flaming splint to the mouth ofeach test tube. If there is a slight explosion, or

if the gas burns, it is probably hydrogen. The wordequation for the reaction in test tube number 2 is:

magnesium + hydrochloric acid--> hydrogen + magnesiumchloride

Note that not all metals replace hydrogen.

This activity may be repeated using dilutesulfuric acid instead of hydrochloric acid. Vinegarmay also be used but the reactions tend to be very

slow.

REFERENCE OUTLINE

J-106


MATERIALS

dilute hydro-chloric acid

vinegarlimestone/marblechips

any soluble car-bonate compound

KEY WORDS

ACTIVITIES

ACIDS REACT WITH CARBONATES

Pour a few milliliters of dilute hydrochloricacid or vinegar into a 10-ml. solution of washing

soda or any soluble carbonate compound. Note the

effect when a few drops of acid are placed onlimestone or marble chips (calcium carbonate).Point out that geologists use the acid test to iden-

tify many rocks as carbonates.

J-108


(1) sources of Acids are found in a variety of

acids natural products.

Acids can be made by chemicalchanges, such as reacting anonmetallic oxide with water orcombining a salt with concentratedsulfuric acid. (For further detailsconsult a high school chemistrytextbook.)

(2) uses of acids Acids play an important part in themanufacture of mary products.

Some acids are important in thedigestion of our foods.

b. bases The properties of a compounddetermine if it is a base.

Bases can turn litmus blue andcolorless phenophthaiein red.

Bases can counteract or neutralize

acids.

The solution of a base feelsslippery or soapy.

pH paper makes an excellent indica-tor for bases.

MATERIALS

pH paperbeakersfruit juicesbaking sodawashing sodavinegarhousehold ammoniasink cleanersoapmilk of magnesiasoil-testing kitvarious samplesof soils

litmus

KEY WORDS

counteractdigestionindicatorneutralizenonmetallic oxidephenopthalein

J-109

ACTIVITIES

TEACHER NOTE:

Acids *have a sour taste.testing of compounds for thisnot be undertaken by pupils.excellent indicator.

However, theproperty shouldpH paper makes an

In many ways pH paper, which is obtainablefrom any supply house, is a much more suitable in-dicator than litmus paper. This indicator goesthrough a wider range of color changes and can beused to indicate the relative strength of acids

and bases.

Using pH paper, test fruit juices and othercommon substances, such as baking soda, washingsoda, vinegar, household ammonia, sink cleaner,soap and milk of magnesia.

TESTING SOLUTIONS WITH INDICATORS

ACIDS NEUTPAL BASES

Hydrochloric.1(

STRONG ACIDS

LITMUS 6PAPER Red

Vinegar

Punk

PPHAPER tecihr E Orange

wol-erNEuTPAL

BakingSoda

DitureLye

...-

STRONG BASES

LBliguhe

Bler

uUDcrik

Greert

7Be

Carry on a soil-testing experiment, using aregular soil-testing kit if one is available.Follow the directions included with the kit anddiscuss the importance of maintaining correct soilconditions for various crops. Point out reasonswhy some soils become too acid and explain why limeis used to neutralize the acid.

REFERNCE OUTLINE

J-110


J -ill

MATERIALS ACTIiTITIES

If a regular soil-testing kit is not available,

satisfactory results can be obtained by adding a

samPle of soil to some water in a beaker. Allow

the mixture to settle until there is a layer of

clear water at the top. This water will containdissolved matter and can be tested withlitmus or pH paper.

TEACHER NOTE:

(An hydroxide compound such as ethylalcohol (C H OH) should not normally be

2 5

classified as a base since it does not affect

litmus and phenophthalein or neutralize acids.)

275

J-112


(1) formation of Bases are made by chemical changes.

basesBases are made by combining some metalslike calcium with water, by reactinga metallic oxide with water, or bya double replacement between a solublebase and a metallic salt solution.

(2) uses of bases Bases are used in a variety ofindustrial processes requiring theneutralization of an acid.

Some bases are used to make soap.

Milk of magnesia is a suspension ofmagnesium hydroxide and water. It

is used to neutralize acid and as a

cathartic.

MATERIALS

magnesium ribbontest tubewaterlitmus paper (orsome indicator)

litmus or pH papervarious laundryand hand soaps

lye (sodium hydrox-ide) solution

fat (olive orcoconut oil)

alcohol (rubbing)evaporating dishbunsen burnerbeaker

KEY WORDS

catharticindustrialprocessessuspension

J-113

ACTIVITIES

BASE-FORMING ELEMENTS

Caution: Remind pupils not to look directlyat burning magnesium.

Burn 10 cm. of magnesium ribbon and add thewhite magnesium oxide that is formed to 10 ml. ofwater in a test tube. Heat the water to theboiling point in order to dissolve as much oxide

as possible. Determine whether the solution isbasic by means of the litmus paper, phenophthalein,or pH paper.

The word equation for burning magnesium is:

magnesium + oxygen magnesium oxide2Mg + 0 2Mg0

2

The oxide reacts with water as follows:

magnesium oxide + water--> magnesium hydroxide

The teacher may wish to demonstrate that metalstend to form bases by reacting various oxides withwater.

Compare the amount of free alkali in variouslaundry soaps and hand soaps, using litmus or pHpaper. Discuss the differences between laundrysoaps and hand soaps.

Soap can be made quickly in the laboratory byusing alcohol as a solvent for the lye and fat. Add10 ml. of rubbing alcohol to two teaspoonfuls ofolive or coconut oil in an evaporating dish. Add5 ml. of a 20 percent solution of sodium hydroxidesolution. Heat the mixture gently with a small flame.Continue heating and stirring it until the odor of

alcohol has disappeared.

277

J-1114


J-115


The pasty mass remaining is a mixture .):C

soap and glycerine. The soap may be separatedfrom the glycerine by pouring the mixture intoa beaker containing a warm saturated solutionof salt. Stir this mixture for one minute andallow it to settle. The soap collects at thetop and may be ladled off. Try making suds byshaking a small amount of the soap with sometapwater in a test tube. Test the soap with redlitmus paper.

Point out that the commercial process is

slower than this method because it is too expen-sive to use alcohol as the solvent. Discuss theuses for the by-product glycerine.

Pour mixtureinto saltsoluhon

Mix alcohol andoil, add sodiumhydroxide solution

and heal-

KEY WORDS

Warmsaturated

salt soluhon

279

Stir mixtureand allowo cool

Soap

Glycerineand

salt water

J-116


c. salts

(1) source ofsalts

contains the positive ion

from a base and the negative ionfrom an acid.

The properties of salts vary widely.

Most salt compounds are found inthe minerals of the earth and in

sea water.

Salts may be made by neutralizationof an acid by a base. However,normally commercial quantities arenot made in this way. The salts areusually found in nature or producedby other chemical reactions.

(2) uses of salts The uses of salts vary from season-ing and preserving food to softeningwater, making acids or bases,fertilizers, drugs, and explosives.

B. Mixtures

1. suspensions

A mixture contains two or moreelements and/or compounds which maybe separated into its constituentparts by physical means.

The composition of a mixture mayvary.

Some mixtures have propertiessimilar to both solutions andsuspensions because the size of thesuspended particles lies betweenthose in a solution and those in asuspension. Mixtures exhibitingdual properties are called colloids.

Suspensions are mixtures containingparticles which readily settle outof the water (liquid).

Suspensions can be separated intotheir constituent parts by filtering.

Like all mixtures, a suspension canbe made in varying proportions.

J-117


KEY WORDS

J-118


True suspensions are opaque to thepassage of light and their particlesare visible. If during filtrationof a suspension the filtrate appearsto be cloudy, some suspendedparticles are small enough to passthrough the filter and the filtrateis really a colloidal dispersion.The original mixture was, therefore,both a suspension and colloid.

282

MATERIALS

muddy wateralum

ACTIVITIES

TEACHER NOTE:

Although salts have a salty taste, most

of them are poisonous so the property should

not be tested.

Put some of the impure muddy water in a

tall jar and add a small amount of alum crystals.

Stir the mixture and allow it to settle. The

alum forms a jellylike mass which entangles the

dirt particles and carries them down as it settles.

This process, which is called coagulation, is

used by many cities in removing suspended matter

from the water supply.

MAKING SUSPENSIONS

insoluble material Suspensions can be made by the pupils from

silver nitrate water and any insoluble material providing the

sodium chlorude solid particle size is large enough to allow

water separation by filtration.

graduatestest tubesfilter paperfunnelringringstand

KEY WORDS

coagulationcolloidal dis-persioncolloidscommercialdrugsexplosivesfertilizersmineralsopaquepreservingseasoningsuspensionvisiblewater softener

Fine sand, coarse dirt, and water can be

mixed to form a suspension. If necessary, add a

pinch of alum crystals to coagulate the mud

particles so they can be filtered. The action

between silver nitrate and sodium chloride solu-

tions produces a suspension of silver chloride in

sodium nitrate solution. Any chemical reaction

producing a precipitate can be used to make a

suspension.

After the suspension has been made, call the

pupils' attention to the cloudy nature of the sus-

pension. Allow the suspension to settle. Then

shake the mixture to reform the suspension; filter

it.

28.3

REFERENCE OUTLINE

2. solutions

a. parts of asolution

b. saturating asolvent

J-120


The particles in a solution are toosmall to be filtered or to settleout of the liquid.

A solution is clear and uniform.

A solution can be made in varyingproportions.

The solute is the part of a solutionthat dissolves, while the solvent isthe dissolving medium.

Water is the most common solvent.

The solute may be in the gaseous,liquid, or solid state. Likewise,the solvent may be in any one of

the three states. Therefore, thereare nine different types of funda-mental solutions.

A given amount of solvent cancontinue to dissolve solute until apoint is reached where no moresolute can dissolve. Before thatpoint the solution is unsaturated.At that point the solution issaturated at that temperature.

A supersaturated solution containsmore solute than it can dissolve atthe existing temperature. It wasprepared by dissolving of soluteat a higher temperature.

As a crystal starts to dissolve, theions going into solution migrate soslowly throughout the solution thatthe solvent in the vicinity of thecrystal rapidly becomes saturated.The rate of dissolving decreasesnoticeably. Stirring or agitatingthe solvent allows unsaturatedsolvent to approach the crystal,and the rate of dissolving increases.Dissolving stops when the entiresolvent becomes saturated or whenthe solute has all dissolved.

284

MATERIALS

KEY WORDS

agitatingconcentrateddissolvingformationfundamentalsaturatedsolutesolventstirringsupersaturateduniformunsaturated

J-121

ACTIVITIES

USING AN OVERHEAD PROJECTOR TO SHOW THE

FORMATION OF A SOLUTION

Place a petri dish containing some water on

the overhead projector. In the center of the

dish place a tiny crystal of potassium permangan-

ate. Have the pupils watch the action for a few

minutes. Gently swirl the dish, and again have the

pupils observe the crystal. Ask for a possible

explanation of the action.

If pupils are given enough time to observe the

formation of the solution, they usually will come

to the conclusion that the crystal is dissolving

to produce a pink solution and that the pink solu-

tion becomes darker as more of the crystal dissolves.

Some pupils will note that the color moves outward

from the crystal. The darkening and spreading stops

when the water near the crystal cannot dissolve any

more solute. When "new" water comes near the crystal,

more solute is dissolved until the darkening and

spreading action stops again.

Introduce the term, saturated, to describe the

situation which is present when no more solute can

dissolve. Point out that eventually all the water

in the dish can become saturated, if enough solute

is present, and that no more solute can be dissolved

at that temperature.

The term, concentrated, can be used in connec-

tion with the darkest portion. As more solute

dissolves, the solution becomes more concentrated.

Do not use the words strong or weak, in connection

with solutions. The two terms refer to the

strength of acids and bases.

All pupils at this grade level should consider

the solutions in which the solvent is a liquid.

Discuss some of the other types as enrichment for

the better students.

25

J-122


J-123


SATURATED AND UNSATURATED SOLUTIONS

KEY WORDS

On the stage cf the overhead projectorset two petri dishes, one containinv some water,

the other an eaual volume of a saturated sodiumthiosulfate (hypo) solution. Drop a singlehypo crystal into each dish. After the actionhas been observed for a few minutes, drop anotherhypo crystal in each dish. Stir each solution.Ask the pupils to explain why the crystal dis-appears in one dish and not in the other.

If an overhead projector is not available,use larger quantities of liquids in 250-ml. beakers.

USING AN OVERHEAD PROJECTOR TO SHOWSUPERSATURATION

Place two petri dishes, each containing onecrystal of hypo on the overhead projector. Into

one dish pour a saturated hypo solution; into the

other dish pour supersaturated hypo solution. The

latter solution will fo7m excess crystals uponbeing poured into the dish. The seed crystalpresent in the dish makes the excess solute imme-

diately leave the supersaturated solution which

then becomes saturated. Relate the demonstrationto the way in which unsaturated, saturated, andsupersaturated solutions can be identified.

For best results, prepare the supersaturatedsolution just before classtime and store the solu-tion in the container in which it was prepareduntil using it.

If an overhead projector is not available, uselarger quantities of reagents and larger beakers.

J-124


c. factors affecting The amount of solute that can besolubility dissolve'!, in a definite quantity

of solvent depends upon severalfactors.

Polar solvents such as water candissolve polar solutes such assalts of sodium and potassium.

Nonpolar organic chemicals such asgrease dissolve best in nonpolarsolvents. Some nonpolar solventsare carbon tetrachloride, chloro-form, and kerosene.

Alcohol has a molecule, one end ofwhich is polar, the other nonpolar.Alcohol dissolves many polar andnonpolar substances.

(1) nature of Solutes vary in their ability tothe substances be dissolved in a solvent.

(2) size ofparticles

(3) agitation

(4) temperature

Solvents vary in their ability todissolve different solutes

If other factors are the same, smallparticles of a solute dissolve morerapidly than large particles.

Pulverizing the solute increasesthe surface area that can beexposed to the solvent.

If other factors are the same,solutes dissolve more rapidly ifthey are stirred.

Solids usually become more solublein a given amount of solvent asthe temperature increases. Gasesbecome more soluble if the tempera-ture of the solvent decreasesproviding the pressure remains thesame.

Increasing the temperature increasesthe ability of the solute to dis-solve since molecular action at thesurface of the crystal is increasedas the temperature increases.

MATERIALS

test tubeswaterpotassium per-manganate

beakerssugarwater

lump sugarbeakerswater

KEY WORDS

nonpolarpolarpulverizing

J-125

ACTIVITIES

Colored solutions enable pupils to see both

the uniform distribution of particles and varying

degrees of concentration. Arrange six test tubesof water in a test tube rack and add increasingamounts of a colored substance such as potassiumpermanganate and shake until each is completelydissolved. If only a few crystals are used in

the first, the colors will range from faint pinkfor dilute to a deep purple for concentrated.

Fill each of two small beakers with granulatedsugar to a depth of one-half inch. Add water toeach beaker until it is nearly full. Stir onebut do not stir the other and note the time re-quired for each to dissolv,e. Point out thatenormous quantities of sugar are wasted in the

bottom of cups of tea and coffee as a result ofnot stirring.

Obtain two pieces of loaf sugar and crushone in a mortar. Place the lump of sugar and the

crushed sugar in separate beakers and add anequal amount of water to each. Stir the contentsof each beaker and note in which the sugar dissolvesfaster. Point out that more surface is exposed tothe water when the lump is broken uP into smallparticles and therefore the dissolving action takesplace faster.

EFFECT OF SURFACE AREA ON RATE OF DISSOLVING

Obtain a large crystal and an equal weight oftiny crystals of potassium dichromate or coppersulfate. Place two petri dishes containing equalvolumes of water on the overhead projector. Into

one dish drop the large crystal, into the other

dish the small crystals. Observe the action ineach dish for several minutes. Compare the colorof the solution in the dishes. Ask the pupils fora possible explanation of the results. Usuallythey will suggest that more water comes in contactwith the small crystals than with the large crystal.

289

J-126


MATERIALS

KEY WORDS

J-127

ACTIVITIES

EFFECT OF TEMPERATURE ON THE SpLUBILITYOF SOLIDS

To 100 grams of potassium bromide in abeaker add 100 ml. of distilled or deionized

water. Stir until no further solution seems to

take place. Observe the temperature. Ask the

pupils to determine the weight of the salt now

in solution by referring to solubility tables.

Have them predict how warm the solution wouldhave to be to dissolve all of the salt. While

stirring frequently, heat the solution to the

selected temperature. Place a little of the warmsolution in a test tube or in a petri dish to

cool. With an overhead projector show whatoccurs within the petri dish as the solution

cools. Ask the pupils to explain why crystalsappear in the dish as the temperature of the

solution decreases.

291

REFERENCE OUTLINE

*(5) pressure

d. solubilitycurves

optional

J-128


*If other factors are the same,the solubillty of a gas in asolvent varies directly with thepressure to which a gas is sub-jected.

A solubility curve (graph) is amathematical picture which showsthat a definite amount of solventcan dissolve different amounts ofsolute at various temperatures.The solution in each case is alwayssaturated since no more solute canbe dissolved at the given tempera-ture.

The horizontal axis of the graphrepresents (unless stated otherwise)the centigrade temperature of the

solvent.

The vertical axis of the graphrepresents (unless stated otherwise)the grams of solute that can dis-solve in a specific amount of sol-vent, usually water.

The amount of solvent may be ex-pressed in 100 ml. or 100 grams of

solvent. Be sure to check theintroduction to any data found inhandbooks to learn which system isbeing used.

Several curves may be set up usingthe same set of axis. However, thename of solute must be written oneach curve since each solute has itsown individual solubility curve.

J-129


EFFECT OF TEMPERATURE ON THE SOLUBILITYOF GASES

Place-a bottle of soda water in ice water,

chill and open. Allow a second bottle to remain

open at room temperature during the period. At

the end of the period pour the contents of both

into two glasses. Compare the amount of foam

and the temperature of both solutions. The

amount of foam is a rough approximation of the

amount of gas that was dissolved in each solution.

KEY WORDS

axiscurvegraphsolubility curvesolubility graphsolubility table

EFFECT OF PRESSURE ON THE SOLUBILITY OF GASES

Display two bottles of soda water that havebeen standing at room temperature for a period

of time. Take the cap off of one bottle. Ask

the pupils to explain why gas escapes from thesolution in the open bottle and why there are nobubbles of gas seen in the liquid in the capped

bottle.

TABLE OF SOLUBILITIES IN WATER

i-nearly insolubless-slightly solubles-solubled-decomposesn-not isolated

..0

to

0OFto

v--I

0.0

04)

moJaf.0=0

0-.-1

ko

.--1

0

0

xok

IV>,0..-IY4.0,c

0v-1IV

--t

.0tot..3c

0vw-I

o

00=04to00.

..0,0

t...,

.--10=0

0vw-It....,to

aluminum ssnsissiisdammonium sssssssnsssbarium ssisssssiidcalcium ssisssssssiss d

copper II (cuprous) s s i sidsiisiiron II (ferrous) ssisissiisiiron III (ferric) ssnsissiiss d

,-

lead s ssississsiiiimagnesium ssisissiisdmercuryI(mercurous) ssiiinisii ss

mercury II (mercuric) sssisiisiidipotassium ssssssssssssilver ssiiinisiiss i

sodium sss.ssssdssszinc ssisissiisi

29a

REFERENCE OUTLINE

J-130


MATERIALS

KEY WORDS

J-131

ACTIVITIES

USING A SOLUBILITY TABLE

After showing pupils a solubility table,ask them to list the solubilities of substances

such as sodium chloride, barium sulfate,potassium nitrate, copper sulfate, zinc hydrox-ide, and calcium sulfate.

Have the pupils decide which classes cfcompounds seem to be always soluble. (The

ammonium, nitrate, sodium and potassium com-pounds are always soluble.)

295

REFERENCE OUTLINE

(1) uses

J-132


The data used to make solubilitycurves have been obtained byexperimentation.

Solubility curves are used topredict the amount of solute thatmay dissolve in, or precipitate out

of, solution as the temperature is

changed.

A solubility curve shows the tem-perature at which a given amount ofsolute will saturate 100 grams of

water.

A solubility curve can be used toshow how much additional solute isneeded to keep a solution saturatedas the temperature increases.

A solubility curve can be used toshow how much solid will crystal-lize out as a saturated solutioncools.

29e

J-133


KEY WORDS

crystalizecool

200

190

180

170

160

150

140

130

120

110

100

90

so

70

60

so

40

30

so

10

Solubility Curves

// .

IIIbAll

, ..:04

4,:0,al di!11112 oe

.....0, AIwosiiiUUUUP

EMIPria Err-i

.90All00

WWIIco, 4Lithium Hydroxide ummontill

0 10 20 30 40 50 80 70 80 90 100

Temperature - Centigrade

SOLUBILITY CURVES-

(a) Introducing Solubility Curves. Before

class time prepare a solubility curve to be shown

to the pupils. The curve may be drawn on the

blackboard, mimeographed, or printed on .a trans-parency for projection on an overhead projector.

297

REFERENCE OUTLINE

J-134


J-135


Introduce the pupils to the graph by telling

them that a solubility curve is a mathematicalpicture or story about how the solubility of asubstance changes as the temperature changes.Since the "story" concerns only two variable charac-ters, the amount of solute and the temperature, all

the other factors such as the amount of water orother solvent used must remain the same.

KEY WORDS

Have the pupils study the curve for a few

minutes. Ask the pupils to tell what informationthey have found about the axes. Review with themthe way in which to read a graph: Read crosswisebetween the weight of solute axis and the curve;read up and down between the curve and the temper-

ature axis.

Have the pupils determine how much solute isneeded to saturate 100 grams of solvent at dif-

ferent temperatures.

Remind the pupils that if a solution doesnot contain as many grams of solute as the curveindicates it can, the solution is unsaturated.More solute must be added to saturate it. On

the other hand, a supersaturated solution wouldhave more grams of solute dissolved than the curveindicates it can at the existing temperature.The difference between the amount of solutepresent in a supersaturated solution and t le

amount the curve shows is the weight of crystalsthat would come out of the supersaturated solution

as the solution returned to the saturated condi-

tion.

TEACHER NOTE:

Material in section (b) is an optionaldevice depending upon the depth to which theteacher desires to go or the ability of the group

to understand.

(b) Plotting a Solubility Curve. Pupils can

plot a solubility curve from data obtained fromreferences or from experimental data they obtain.

299

3-136


J-137


(1) Using Data from Resources. Give thedata shown which is needed to plot the solu-bility curIze of copper sulfate. Have the pupilsset up the temperature scale on the horizontalscale. The data are plotted and a curve drawnconnecting the points. Unless a straight linecurve is clearly indicated, do not have thepupils use a ruler to connect consecutive points.A line should be lightly drawn free hand con-necting the points, smoothed out and thendarkened to give a satisfactory curve. Labelthe curve with the name of the solute.

It may be wise to review the plotting ofpoints. Stress the need to check each point

plotted. Read down the line from a point tocheck the temperature; read across the line tocheck the weight of solute.

Solubil-1ty of certain anhydrouscompounds In grams per 100 gramsof 820

woo

zc_1

17.5 75.4

90° -KEY WORDS 0 80° 15.3 55

ji 70° No*3

ct.no 13.8 40

50° 13.3 33.3

40° 13 28.5

2 30° 12.9 25

0E. 200 12.8 20.7

10° 12.7 17.4

o° 12.7 14.3

301

aea"

104.0 222.5

99.2

95.0 131.8

90.0

85.5 150

80.2

75.5

70.6

65.2

135.8 :

123.2

111.9

102.4

59.5 93

53.5 85.2

REFERENCE OUTLINE

ATI. Introduction toOrganic Chemistry

A. Definition

B. Some DifferencesBetween Organic andInorganic Compounds

C. Bonding in OrganicCompounds

1. Covalent bonds

2. Formation ofmolecules

a. hydrogenmolecule

J-138


Organic chemistry is the chemistryof the compounds of carbon.

Organic compounds generally differfrom inorganic compounds in that:

there are many more organiccompounds than inorganiccompounds.

organic compounds are moreeasily decomposed by heat.

organic compounds char whenheated.

solutions of organic compoundsare usually poor conductors ofelectricity.

organic compounds are usuallyslightly soluble in water.

organic compounds tend to reactmore slowly than do inorganiccompounds.

Some atoms tend to combine by shar-ing electrons. A pair of electronsshared between two atoms consti-tutes a bond between the atoms.

Atoms tend to share electrons insufficient quantity to brillg theelectron number to the maximumamount for the outside ring.

Some molecules are formed bycovalent bonding.

Two hydrogen atoms join by acovalent bond to produce a mole-cule.

302

3-139


KEY WORDS

Note to Teachers

This unit on organic chemistryis optional.

Although the new methods of teachingbiology presupposes a prior knowledgeof chemistry and chemical principles,the time element during the ninthgrade usually permits only a suDer-ficial review of organic chemistry.

In classes where the pupils have showna good grasp of inorganic chemistry,teachers may elect and should extendthese chemical experiences of theirpupils into the field of organic chem-istry. Where classes are slower moving,this unit may well be omitted.

It is anticipated that biology teacherswill evaluate the background knowledgethat pupils have in chemistry and willproceed to teach the principles ofbiochemistry from this base.

43


A pair of shared electrons may berepresented by a dash (-) or bytwo dots (:).

A structural formula-representsthe atoms present in a moleculeand the bonds joining them.

Other gases with molecules havingcovalent bonding include oxygen,nitrogen, fluorine, and chlorine.

J-ll4l


KEY WORDS

bondingcharconductorcovalentdecomposedformulainorganicmoleculeorganicsolublestructural

REFERENCE OUTLINE

b. methanemolecule

c. formation oflong chains

d. saturated andunsaturatedcompounds

J-142


The carbon atom has four electronsin its outer shell. Carbon tendsto form compounds with other atomsby four covalent bonds.

In methane (CH4, the carbon atom

is Joined to each of four atoms ofhydrogen by a covalent bond.

Carbon atoms have the ability toproduce long chains or rings byforming covalent bonds with othercarbon atoms.

Each carbon atom in a compound maybe joined to another carbon atomby sharing one pair of electrons(one covalent bond). This com-pound is considered saturated.

An example of a saturated compoundis ethane ( C H

6) represented as:

2

YH--C--C--H

I I

H H

Note that there is only one bondbetween the carbon atoms.

Examples of unsaturated compoundsare C H and C H . Their struc-

2 4 2 2

tural formulas are:

H HI 1

H--C.mC--H

and

Note the double and triple bondsbetween the carbon atomS'.

;106

J-l43


KEY WORDS

atombond'compoundringsaturatedshellunsaturated

REFERENCE OUTLINE

D. Some Classes ofOrganic Compounds

J-1/04


Classes of organic compounds may berecognized by the number andarrangement of certain atoms orgroups of atoms in their struc-tural formulas.

1. Hydrocarbons Hydrocarbons are compounds ofhydrogen and carbon.

Hydrocarbons may be in the form ofstraight chains or rings, and maycontain from one to over fortycarbon atoms.

The most abundant sources of hydro-carbons are petroleum and naturalgas.

2. Alcohols Alcohol may be formed by oxidizinghydrocarbons.

Alcohols may be derived fromsaturated hydrocarbons by substi-tuting one or more -OH groups forone or more hydrogen atoms.

Alcohols may result from the addi-tion of OH groups to unsaturatedhydrocarbons.

a. methY1 alcohol The formula for methyl alcohol(methanol) is CH OH.

3

'Methyl alcohol is used to makeother organic compounds, and as asolvent and automobile antifreeze.


methane(CH4)

HCH

H HI I

ethane H---C---C---H(C2H6) I 1

H H

H H HI I I

propane ---_CH_---C---C---H(C3H8) I I I

H H H

H HHHI 1 I I

butane H---C---C---C---C---H

(C4H10)1111H HHH

Show by diagram or molecular models

how one H atom in. ethane (C2H6) is

3.eplaced by an -OH to produce

ethyl alcohol (ethanol). Thestructural formula of ethyl

alcohol is

H H1 IHCC--OHI I

H H

Discuss alcohol as a narcotic and the

KEY WORDS physiological effect on the human organism.

antifreezederivativehydrocarbonnatural gasoxidizingpetroleumsolventsubstitution

REFERENCE OUTLINE

b. ethyl alcohol

c. other alcohols

3. Organic acids

J-146

MAJOR UNDERSTANDINGS ANDFUNDADMNTAL CONCEPTS

The forraula for ethyl alcohol(ethanol) is C H OH.

2 5Ethyl alcohol is used o make otherorganic compounds and is a solvent.

Alcohols are arlion-g the earliest

noc

ganic compounds. Grainethanol) has been obtainedlaon

from fermented starches (grains)

since the begitning of recorded

history.Fermentation is still an

important source of ethanol.

Ethylene glycol. C2H4(01.02, and

glycerol. O3H500103 are examples

of other alcohols.

Ethylene glyco l is used as an

automobile antifreeze.

The structural formula of ethyleneglycol is

H HI 1

I 1

H H

This compound has 2 -OH groups.

The structural formula of glycerolis

OH OHI I I

H---C--_c_--c---HI I 1

H H H

This compound has 3 -OH groups.It is a part of all body fats.

organic acids May be prepared byoxidizing alcohols.

Organic acids have a characteristic

carboxyl group,

.Tha general formula for an organic

acid is

31OH

J-1148


-- --a. amino acids

b. esters

r

Aadno acids are organic acids inwhich an amino (-- NH 2 ) group has

replaced a hydrogen atom.

Amino acids are units which make

up proteins._

The amino acid derived from acetic(ethanoic) acid is represented bythe formula:

0

_

Esters can be formed by the reac-tion of an organic acid and analcohol.

The general formula for an ester is

0

R------0---R

Animal and vegetable fats and oilsare esters which are made up ofglycerol and fatty acids.

MATERIALS

test tubesbeakerbunsen burnerring tripodwire gauze/asbestos pad

KEY WORDS

amino acidsfatsfatty acidsesteroilsproteinreaction

J-3.49

ACTIVITIES

Discuss the commercial uses of esters,especially in the food industry.

ESTERIFICATION

Esters are most frequently prepared by the reaction of alcohols

and acids in the presence of concentrated sulfuric acid. Nhen the

acid used is an organic acid, many of the esters resulting from such

reactions have odors characteristic of certain fragrances produced

by plants. It is possible to prepare various esters in the.labora-

tory which pupils may readily recognize.

In separate test tubes place the amounts of acids and alcohols

as indicated below. Add a few drops of concentrated sulfuric acid

to each tube. Heat by placing the tube in a beaker of heated water.

Try tc identifY the fragrance.

a. 5 ml. of methyl alcohol and 2 gm. of salicylic acid

(wintergreen fragrance results).

b. 5 ml. of ethyl alcohol and 5 mi. of butyric acid

(pineapple odor results).

c. 5 lc. of n -amyl alcohol and 5 ml. of acetic acid

(banana fragrance results)

EssImm ESTER ., EsstxcE arm

Apric0 Amylbutyrate Pineapple Ethyl butyrate

: Banana Anima acenae 'Raspberry.

Isobutyl formateIsobutyl acetate

Grape Ethyl formateEthyl heptoate

Rum Ethyl butyrate

Orange Octyl acetate Wintergreen Methyl salicyIate

REFERENCE OUTLINE

VII. The role of chemistryin society

A. Use of chemicals

B. Conservation ofnatural resources

1. using substitutes

2. using protectivecoatings

3. salvaging wasteproducts

4. proper disposal ofwaste products

C. The balance of nature

J=150

MAJOR UNDERSTANDINGS ANb


Every living organism deDends on

chemical processes.

Most of our natural resollrees are

being rapidly consumed (or made

difficult to reuse) as the demand

for chemical products increases.

Scientists .9.742' constantly searchingfor ways to conserve our stockpile

of resources.

Using a substitute consslwes a

resource in short suPPly.

Protective coatings Prevent or slow

down chemical reactions wiliob re-

duce the usefulness of a substance.

The effective use of waste products

reduces the drain on oub resources.

Proper disposal of wast vroductsprevents pollution of otxr- natural

resources in the air,the earth.

14tery and

The use of chemicals to improve somefeature of man's environment mayaffect seriously some other feature.

3 1 4

J -15l


The corrosion of metal is a serious problem.Since most pupils are interestei in automobiles,the corrosion of metal on automobiles and waysto prevent corrosion provide a motivating ap-proach to the topic of conserving metals.

Advantages and disadvantages of the use ofsalt on city streets should be discussed.

Water pollution is a serious problem in theRochester area. What steps have been taken orare planned to reduce the pollution of the en-vironment in the Monroe County area?

How do the use of pesticides affect thebalance of nature?

KEY WORDS

corrosionconservationsalvageprotective coveringpesticides

BLOCK K

ENERGY AT WORK

.3-16

K-1

ENERGY AT WORK

EleeVric energystatic electricityc4rrent electricity

magrietl_sm

1.(nds of magnetsTagn,.tic fieldsL:Irect current motorinduced voltage

Liolt

soLInd

Tlectromagnetic radiationintensity and illuminatiorireflection of lightrfraction of lightcolor

soUrcescharacteristics of sound ur-avesreflectionresonance

.1ergy'flternal energYteMperature2-eat'ransmission of heat energyPhases of matterelpansionconservation of heat energy

ImP°1:tant concepts are indioated by the symbol (#). Materials

collsl-dered of an enrichment nature are indicated by an

asterlsk (*).

-E.-PERENCE OUTLINE

Electric Energy

A. Static electricity

1. structure ofmatter

K-2


Electric energy is one form ofenergy.

Under proper conditions, electricenergy may be transformed intoother forms of energy, and vice

versa.

Static electricity may be defined

as a collection of similarelectric charges "at rest"

Matter is composed of particlescalled atoms.

a. subatomic The atom is composed of threeparticles fundamental particles: the

proton, the electron, and the

neutron.

b. atomicstructure

The proton is a positivelY charged

particle.

The electron is a negativelYcharged particle with a mass 1836

times smaller than the proton.

The neutron has no charge and is

about the same size ;7-, th e proton.

The nucleus is a dense mass con-

sisting of protons and neutrons.

Electrons move about thein various shaped orbits.

nucleus

Z-:413

MATERIALS

XEY WORDS

electric energystaticelectricityatomelectronDrotonlieutronIlucleus

ACTIVITIES

#It is important to point out that "atrest" does not mean that the bharges arennot

in motion. The electrons inv olved are in motion;

but the motion is random rather than in a parti-cular direction , as in current electricity.

An atom is the smallest unit of a substance(matter).that can take part in a chemical change.

A molecule, usually, is a combination of twoor more atoms. (Exceptions: mono-atomIc-moleculessuch as Hg, He, Ar, etc.) An ion is a chargedatom or group of atoms.

It is important to point out that thearrangement of electrons is three-dimensional.

The radius of the atom is at least 104

(10,000) times the radius of the nucleus. Mostof matter is empty space.

REFERENCE OUTLINE

2. uncharged andcharged objects


charge objects have an equalnumber of positive and negativecharges.

Uncharged objects normally donot attract small bits of matter.

Charged objects have unequalnumbers of positive and negativecharges.

Charged objects have gained orlost electrons so that thenumbers of positive and negativecharges are unequal.

Charged objects normally attractsmall bits of matter.

320

K-5

NATERIALS ACTIVITIES

#Touch a bit of paper with a hard rubber

rod, comb or fountain pen. Strokerod

vigorously with a piece of wool orfur and

bring it near the paper. Ask the class forexplanations of the effect produced. Invite

Pupils to recount their experiences.witll staticelectricity.

There are many other interestingstrations for producing static electric chargesand observing their effects. Pupils MaY already

nature

be familiar with some of these, but at Oane: a

few should be repeated for the purpose ofdeveloping the concept of the elect-r'ica

Of matter. The distinction between neutal andcharged bodies should be pointed out; ar2-u the

explanation of how objects become p0e5.tive1y

negatively charged should be made in terms of

gain or loss of electrons. A reasonahlY drydaY should be selected for theee demonstrat ions.

#Rub a hard rubber rod with wool or fur

and plunge it into a box of puffed rice.Withdraw the rod from the box and observe the

effect. The first attraction is followed by

matual repulsion and the effect is quitesPectacular.

KEY WORDS #Lay two books on the table several inchesaPart. Place small bits of paper bet

ween the

books and lay a pane of glass over them' Nowrub the glass with a piece of silk and the Paperwill jump up to the under surface of the glass.

#Hold a piece)dfi,paper_ggalnstchalkboard and rub it briskly with

toewaal orpiece of

cloth. If the relative humidity is low enough,

the electric charges will hold the paper inPosition for some time. On humid daYs the

charges will leak off too rapidly to Permit acharge to be built up.

#Stroke a rubber rod with fur and bring it

near the glass of a neon glow lamp. Move therod slowly past the lamp and observe the

discharges.

:3 1

REFERENCE OUTLINE MA3-9-UNDERSTANDINGS ANDL'AMENTAL CONCEPTS

MATERIALS

KEY WORDS

K-7

ACTIVITIES

#Put several small pith balls in a plastic

toothbrush container. Rub ti:e container withfur and stand it on one end. Observe the action

of the pith balls. Suggest that pupils tryother materials in a plastic container.

Pelle of qlwsrc_

IPlashc

1

i tooth brush

a:

5 ortl-oirter, 0

!

16 Smallpithbolts

#Adjust a faucet so that a thin stream ofwater flows from it. Now give a comb a chargeby running it through the hair several times.Hold the comb 2 or 3 cm. from tne stream ofwater. The water is strongly attracted by the

charge on the comb.

Make a list of situations where staticcharges can be dangerous. Emphasize the dangerof dry cleaning with highly volatile, combustiblesolvents at home. Discuss the reason for usingthe chain that dangles from the rear of a gasolinetruck.

Discuss the nature of lightning, how chargesare formed, what the flash represents and whatcauses the thunder. Emphasize the rules ofsafety that should be observed during an electicalstorm.

#The topic of electrostatics presents manyopportunities for spectacular and intriguingdemonstrations. Paradoxically, this is one of itsmajor pitfqlls, since the explanations of many ofof the most interesting experiments involve ratherobscure or advanced scientific principles, orperhaps principles which are better taught inother ways or in other parts of the course. If

K-8


-K-9


KEY WORDS

these explanations are incompletely understood,the whole lesson takes on the atmosphere of afascinating magic show, and entertainmentrather than learning becomes the prime objectiveof the class. In general, an experiment should

not be given class time unless (1) it demon-strates some principle which either is fundamen-tal to concepts to be studied later, has some"daily life" application or satisfies some otheraccepted objective of the course, (2) it can beexplained understandably at the level of theclass being.taught and (3) its entertaining andspectacular features can be used directly tofocus attention on its values for teaching andlearning.

Experimenting with static electricity is

most successful is most successful in cool dry

weather,

Some pieces of equipment, particulary theglass rod, silk threads supporting electroscopeballs and the like, will work best if heatedjust before use. Place them over a hot radiatorbefore class, or have a radiant heater inoperation at one end of the demonstration table.

#The Electrophorus

The electrophorus may be purchased or

constructed. It consists of a shallow plate

which contains insulating material and a metaldisk with an insulated handle. To make one,place some melted sealing wax in a pie or caketin about 6 inches in diameter. Allow the wax

to harden. If desired, a discarded vinylitephonograph record can be melted and used insteadof the sealing wax. A sheet of metal or acircular can lid may be used for the metal disk.Attach a 4 inch piece of wood to the center ofthe disk to serve as an insulated handle.

Rub the wax or vinylite briskly with fur orwool to charge it well. Set the disk on the waxand gr,gmtulthe disk with the finger. Remove thE

REFERENCE OUTLINE

K-10


K-11


finger and lift the disk, which is now charged

and can be used to charge other objects. The

charge on the disk is positive and opposite tothe charge on the wax.

KEY WORDS

The charge on the disk is sufficient todischarge in the form of a spark when held close

to another object. This discharge can cause a

neon glow lamp to flash.

Insaafedhandle

kittalplate

Die tin

,Wax

#Several activities involving staticcharges should be suggested for pupils to do at

home. Suggest that pupils comb their hair infront of a mirror in a completely darkened roomto observe the sparks. Ask them to observe anyeffect on radio receptioni They can also observethe spark discharge when they scuff across arug and touch a doorknob or a radiator. A wide

variety of activities using toy balloons can be

suggested.

REFERENCE OUTLINE

3. electrostaticforces

a. force betweenlike charges

b. force betweenunlike charges

R-12

MAJOR UNDERSTANDINGS AND


If a charged object is placed nearanother charged object, there isan electrostatic force betweenthem.

Life-charged objects rePel each

other.

Unlike-charged objects attracteach other.

K-13


Forces between charged objects are causedby electric fields. The shaP

and theof the bodies,

the amount of charge On the bodi

medium in which the bodies are lo,determine the shapes ami--- the str4

ated,gths of the

fields.

KEY WORDS

electrostaticforces

attractrepelelectroscope

Electrostatic force s are lare as com_g

pared to gravitational .f.orces.

The electrostatic -Pprce

-

betwe

and a proton is about .1.0410

en an electron,-

gravitational attractionlarger than the

between them.

#Electrostatic Forces

Rub two glass rods witri silk will the

rods pick up small bits of paper? Are the rods

charged? Are the rods charged alike? Suspend

each rod from its center by a thread. Bring

the two rods near each other Note the effect:

Repeat the process with two rubber or plastic

rods rubbed with-fur.

Charge a glass rod with silk and a rubber

rod with fur. Suspend the rods; bring themnear each other. Note the effect.

#Several simple electroscopes can be made

for studying electric charges. Suspend two pith

balls or two grains of Puffed rice by lightthreads from a supPort. Toach each simultane-ously with a charged object. Note the repulsion

of two bodies having a like charge. Observe the

behavior of the grains When a Positive or anegative body is brought bet ween 1-1. TT,.I.Lew

REFERENCE OUTLINE

K-3.14


MATERIALS

KEY WORD6

K-15

ACTIVITIES

Pingpong balls painted with aluminum paint,

small balloons and many other light objects can

be used equally well. Balloons can be chargedby rubbing on a coat sleeve.

Neutral Charged Effect of Effect oflike charge opposile charge

Ruler

Neutral

Strip ofnewspaper3-4 crn wide

Charged Effect of like charge

REFERENCE OUTLINE

L. transfer ofcharges

a. conservationof energy

b. charging bycontact

c. charging byinduction

K-16


Electrons may be transferredfrom one object to another.

When electrons are transferredfrom one object to anOther, thenet charge remains the same.

When a charged object touches aninsulated uncharged object, theuncharged object becomes charged.

When an object is charged bycontact, it acquires the samecharge as the charging body.

Objects are charged by inductionwhen there is a transfer ofelectrons between the body andthe ground.

When an object is charged byinduction, it acquires a chargeopposite to that of the chargingbody.

5. storing electrical Electrical charges may be storedcharges by a device known as a capacitor.

MATERIALS

KEY WORDS

transfer ofchargesconservation ofcharges

charging bycontactcharging byinductioncapacitor

IC-17

ACTIVITIES

#Charging By Contact

Charge a rubber rod by rubbin3 with fur.

Touch the rubber rod to the knob of an electro-

scope. Note the effect. Determine if the

electroscope is positively or negatively charged

by bringing a rod of known charge near the knob.

Repeat the entire process by charging theelectroscope with a charged glass rod.

#Charging By Induction

Charge a rubber rod. Bring the rod near

the knob of an uncharged electroscope. Touch

the knob of the electroscope with the finger.

Remove the finger and the rod. Determine the

charge on the electroscope by means of a rod of

known charge. Repeat the entire process with a

cha--ged glass rod.

#The term "condenser" has been replaced

by the term "capacitor." A capacitor is adevice composed of alternate layers of conduc-

tors and insulators.

Capacitors are rated according to charge per

volt. A coulor"b/volt is called a farad. The

farad is such a large unit that most capacitors

are rated in microfarads or micro microfarads

(Ilf or Alaf).

K-18


K-19


#The Leyden Jar (Demonstration Capacitor)

KEY WORDS

Leyden jar

The Leyden jar is a simple form of capacitorwhich consists of two pieces of metal foilseparated by a glass container. Leyden jars arefound on electrostatic machines. If a Leyden jaris not available in the laboratory, one may beeasily constructed from aluminum foil and anErlenmeyer flask.

The foil is placed inside and outside of the

lower half of the flask. A metal rod is insertedthrough a one-hole rubber stopper, and a wire isused to attach a chain of paper clips to the

lower end of the rod. When the stopper is placedin the flask, the paper clips must reach thebottom of the flask and make contact with the

aluminium.

Ground the outside metal of the Leyden jarwith a wire attached to a radiato7,, water faucet,

or electric ground. Charge the metal rod bytouching it several times with a charged electro-phorus disk. (If desired, the rod may beconnected to one electrode of a static electricity

machine.) When a positively-charged electrophorusplate touches the rc-i, electrons leave the roeand the metal insdie the jar. Electrons areattracted from the ground and collect on the metal

outside the jar. Disconnect the ground. Dischargethe capacitor by touching the rod and the outsidemetal with a metal conductor attached to aninsulating handle. Is a spark produced?

:.4 f35

Metal Fo: Iinsideandutside

ElectrophorusConduct-or

Metal rodiII

Paper clipsLN, /enough to

,<"Contact bottomfoil

insulatingGlass handle

Foi I insideandtside

FFERENCE OUTLINE

'1h

K-20

MAJOR UNDLRSTANDINGS ANDFUNDAMENTAL CONCEPTS

K-21


//Charge a one-microfarad capacitor byconnecting it for a short time to a 45-voltbattery. Disconnect the battery and touchtogether the two wires leading to the capacitor.Observe the spark that represents the eleetricaldischarge. Discuss the action of the capacitorin building up and storing an electrical charge.Relate this effect with the electrical dischargethat takes place daring a thunderstorm.

KEY WORDS

K-22

REF..RENCE OUTLINE MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

Current electricity Current electricity Involves he

flow of electric charges.

1. sc)urces ofcurrent elec-tricity

Chemical energy may be t.r'FilH3fmdinto electrical energy by ,-,uch

devices as the

. voltaic celldry cellstorage batteryfuel cell

K-23


1#Cut a strip of copppr Ebout 8 cm. long and

11/2 to 2 cm. wide. Cut a siilar strip of zinc.FasEen a wire to each and connect the wires to a

galvanometer. Touch che copper and zinc together.Observe that there is no indication of an electriccurrent. Dip the strips into a jar containingdistilled water. Repeat the procedure, using in

succession, tap water, salt water and solutionsof other common substances such as sugar, bakingsoda, vinegar, lye and a3cohol. Rinse in cleanwater after each trial. il:ake a list of solutionsby which the galvanometer indicates that acurrent is produced.

KEY WORDS

currentelectricityvoltaic celldry cellstoragebatteryfuel cellgalvanometer

Try two strips of other metals such as tin,steel. lead and aluminum. For one experimentuse two strips of the same metal. List theessential parts of a simple cell.

As a final step insert the strip of copperand the strip of zinc into a lemon and observethe action of the galvanometer. Use other fruitswhich contain acid and compare the results.

Galvanometer

Golvonometer

ZincSolutionsto be used

Lemon

#Prepare a dilute solution of sulfuric acidby slowly adding one part acid to 10 parts ofwater in a Pyrex beaker. When the acid is coolput a fresh copper strip into the solution.Observe that thetre is little evidence of chemical

action. Next pu'; a new strip of zinc into the

solution. Obser7e the formation of bubbles of

a gas which indicates that chemical change istaking place. Al3o examine the surface of the

zinc after it is removed from the acid.

K-214

REFEREN CE OUTLINE MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

MATERIALS

KEY WORDS

K-25

ACTIVITIES

Put both the copper and zinc strips intothe acid and connect to a voltmeter. Observethe voltage and then connect the wires to anelectrical bell or buzzer.

The explanation should be limited to theidea that as a result of chemical action thezinc tends to develop a negative charge (anexcess of electrons) and the copper a positiveCharge (a scarcity of electrons). Whenconnected by a conductor, electrons flow fromthe zinc to the copper.

#Using a hacksaw cut lengthwise through adry cell. Examine this cross section of the

cell. Point out the essential parts and discussthe use of each.

Emphasize the limitations of dry cells andpoint out that they should be used intermittentlyfor longer life.

Discuss the reasons why a dry cell goes"dead" and demonstrate how an old cell can berevived. An effective way to do this is topunch several holes in the container and setit in a solution of salt or sal ammoniac.

//Exhibit several different types of drycells and test the voltage of each with avoltmeter. Connect each to a miniature lamp

and note the brilliance in each case.

Open a "B" batte'2y, "Hotshot" or some otherbattery of this type, to see how voltagesgreater than 1.5 volt3 are achieved. "B"

batteries for hearing aids or portable radiosare suitable for such dissection.

Make a list of the uses for dry cells and

dry batteries.

K-26


'6

K-27


#Make a lead storage cell to illustrate thetype of cell that can be recharged. Cut twostrips of sheet lead about 5 cm. by 20 cm. andsandpaper their surfaces. Fasten wires to each,connect them to a galvanometer or voltmeter andput the strips in a solution of ailute sulfuricacid. Point out that there is no evidence of

an electric current.

KEY WORDS

Now connect the strips to a 6-volt dec.source. Pass current through the solution for

several minutes. Observe the evidence ofchemical action which results in a change inthe appearance of the electrode connected to thepositive terminal.

Disconnect the charging source and readon a voltmeter the voltage of the storage cellyou have made. Connect the new cell to anelectric bell and Allow the cell to "ru,a down."

No attempt should be made to develop acomplete understanding of the chemical actioninvolved in the charging and discharging of astorage cell. A simple explanation in terms ofelectrodes becoming more unlike when the cellis charging and more alike on discharging is

sufficient.Chorging Voll-rneter

Discharging.;%

Soiuhonofsulfuric acid

in water LeadLead dioxide

#Saggest that pupils examine storagebatteries in automobiles. Most of these are12-volt batteries although 6-volt batteries arecommon.

Discuss why batteries require periodicinspections. Investigate other kinds of storagebatteries and discuss the advantages and disad-vantages of different types.

K-28

FEFERENCE OUTLINE MAJCR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

Light energy may be transformedinto electrical energy by a.

photoelectric cell.

Heat energy may be transformedinto electrical energy by a

thermocouple

Mechanical energy can be tiedto turn generators.

MATERIALS

KEY WORDS

photoelectriccell

thermocouple

K-29

ACTIVITIES

#It is important to stress that somedevices transform c.)ne form of energy toelectrical energy. It is suggested thatteachers minimize details of constructionof these devices.

The solar cell is used on many spacevehicles. Information concerning the solarcell may be found in recent encycllopedias andhigh sThool textbooks as well as publicationsof the National Aeronautics and Space Adminis-tration.

#Demonstrate photoelectric cell in alight meter, exposure meter or in a soundmovie projector. Explain that selenium andsome other metals change light.; into a flow ofelectricity. Point out that the electronflow increases as tne inGensity of the lightincreases.

If a demonstration photocell unit isavailable, pupils are fascinated by simplecircuits in which the device is used to ringa be...1, turn on a lisnt or start a motor. Makea list of places where photoelectric cells areused.

#Scrape the paint from a piece of coat-hanger wire. Twist together one end of thiswire and the end of a copper wire. Connect theopposite ends of these wires to a sensitivegalvanometer. Heat the junction of the iron andthe copper wires with a candle flame. Note'thedeflection of the galvanometer needle. Try abunsen burner flame.

This device is a simple thermocouple. Theprinciple illustrated is made use of in electricthermometers for measuring temperature insideengines and in other inaccessf.ble places.

Golvonomet-er

K-30

REFERENCE OUTLINE MAJOR UNDERSTANDINGS ANT',FUNDAMENTAL CONCEPTS

K-31


#Assemble a model generating station,consisting Gf a water motor and a 5-volt

generator. Connect the pulleys on the motor

and the generator with a large rubber band to

serve as a drive belt. Use the output of the

generator to light 6-volt lamps or to ring a

bell. A transmission line from the desk to the

rear of the room can be used to make the model

more realistic. This model illustrates the

energy transformations involved in the commercialproduction and use of electrical energy.

Watermotor

1%----7-:'-\\--"<-

),:-....,/--;?t__;-- -----____1- 6-Volt0:!:1,., ,:, ...L

.tr;;.' .: 4-,LIL,2, ..,j 1

band/ L______ --I (.3'2"fakse

./...L.:...:z .1.":.01

tarrnlssjon ti

KEY WORDS

generator

'6A/olt-lamp

Bell

K-32


2, conductors Conductors are materials throughwhich charges move readily.

a. solids Metals are generally the bestsolid conductors.

Good metal conductors are silver,copper, and aluminum.

4

K-33


KEY WORDS

conductorinsulator

#The pupils should realize that undernormal conditions charges travel readily throughconductors but not readily through JInsIllators.

A conductor must have charges which arefree to move. The availability of these chargesdetermines how well the material will conductelectricity. The amount of electric currentwhich can be conducted depends upon the material.

A good conductor is a poor insulator; a goodinsulator is a poor conductor.

Materials in which electrons are closelybound to their atoms are insulators. Some goodinsulators are rubber, mica, and dry air.

In a metal conductor the free electrons movewhen a source of potential difference (such as abattery) is connected across the metal. Theelectrons move toward the positive pole of theenergy source.

It is possible that simple experiments withthe electrical conductivity of solids have beenperformed in previous grades. In this case, donot repeat.

#Conductivity of Solids

If no apparatus for determining the conduc-tivity of solids is available in the laboratory,a simple form may be devised. Obtain two piecesof bell wire about two feet long. Remove theinsulation from about three inches of the ends ofthe wires. Connect the wires in series with aflashlight lamp and one or two dry cells, asshown. Test the connections by bringing the twobared ends of the wire together briefly. Separatethe bared ends and place a piece of copper wireacross them. Note whether the lamp lights. Ifso, indicate whether it is bright or dim. Repeatthe procedure using wires or small pieces of

K-314


K-35


silver, aluminum, wood, rubber and thread. If

accurate measurements are desire, substitutean ammeter for the lamp.

eigred .L--Test w iremitre I _________,

?

is===.

Lamp Swi tch

KEY WORDS

Asso,ted pcz.5 ofSi r, aluminum.woo.1, rubberarid thread

K-3Z


b. liquids Some good liquid conductors aresolutions of acids, bases, andsalts.

352

K-37


KEY WORDS

electrolytes

#Certain liouids, called electrolytes,are good conductors of electricity.

Electrolytes have both positive (+) andnegative (-) ions available. Under the influ-ence of a potential difference (such as a drycell or battery) both positive and negativeions move toward the terminals of oppositecharge.

#Conductivity in Liquids

Use an electrical conductivity apparatussimilar to that shown in the diagram. Becauseof the considerable shock hazard involved whenoperated from a 120-volt source, it is stronglyrecommended that the teacher demonstrate theprocedures.

Prepare solutions of dilute sulfuric acid,dilute hydrochloric acid, acetic acid, ammoniumhydroxide, sodium chloride (table salt), andtable sugar. Also obtain tap water, distilledwater, and alcohol. Place one liquid in thecontainer until it is about three-quarters full.Insert the electrodes. Connect to the voltagesource. Note whether the lamp is bright, dim,or does not glow. If more accurate results aredesired, use an ammeter in place of the lamp.Disconnect from the voltage source. Use aseries of beakers of the same size, or empty andand rinse the beaker each time. Repeat, usingother solutions. Do liquids vary in theirability to conduct electricity?

25-watl---lamp

.353

----Copperelecl.rJcle

250-mt:15eaker

Adyusl.able_t-rmq clamp

endwire gauze-

K-38


Ionized gases conduct electricit:;c. gases

K-.39


KEY WORDS

ionized gases

#Uncharged molecules of gas become charged(ionized) by a loss or gain of electrons. Gases

may be ionized by high energy radi?tion, bycollisions with high energy electrons, and by

electric fields.

In fluorescent tubes, electrons areaccelerated by a high voltage. The electronscollide with molecules of mercury vapor whichbecome ionized and conduct electricity. The

ions bo.)bard the fluorescent material whichlines the surface of ti-e glass. This materialabsorbs energy and then reemits it in the formof visible light energy.

In gas discharge tubes, a high voltageionizes the gas molecules. The molecules absorbenergy which is later reemitted as visiblelight energy.

Conduction in Gases

Connect a demonstration discharge tube to

a vacuum r mp. Connect the terminals of the

secondary coil of an induction coil to the endsof the discharge tube. Connect the primaryterminals of the coil to a 6-volt d.c. source.Start the vacuum pump and observe the discharge

tube. The demonstration may include the use ofcommercial, gas-filled discharge tubes.

7Discharge tube

To vacuu rnpurrip

-K=140


3. characteristics A source of electric potentialof an electric energy and a continuous pathcurrent (conductor) for charges are

necessary for a complete electriccurrent.

a. voltage

The energy per unit charge ismeasured in volts.

0

K-41


#The potential energy source (such as an

electric cell) provides a force (electric field)

on each charge which causes it to move through

the conductor.

KEY WORDS

voltvol.i;age

A continuous conducting path is called aclosed circuit. An open circuit is one in which

there is -icp complete path.

#At this level, potential difference,voltage difference, and voltage will be consid-ered to be synonymous.

Batteries provide a source of electricpotential difference. A voltmeter connectedacross the terminals of a cell or batterymeasures the potential difference between ',,he

terminals.

#Potential Difference

Connect the terminals of a 9-5 d.c. volt-meter to the positive and negative terminals cfa large dry cell. Repeat with a flashlight cell.

The reading of the voltmeter represents thedifference in potential (voltap;e) between the

terminals.

Support a 2 or 3 foot length cf bareresistance wire and attach the ends to theterminals of a dry cell. Connect one terminalof a voltmeter to one end of the wire and maketne other connection by means of a clip leadwhich can be slid along the wire. As the leadmoves along the wire, note the readings of the

voltmeter. At any point along the wire thereading represents the potential differencebetween the terminal and that point on the wire.

To add variety, wires properly identifiedas positive and negative may be connected to the

terminals of a variety of cells which areenclosed in boxes. Challenge pupils to determinethe potential differences of the cells and topredict what combinations of cells are involved.

:157

K42


b. electriccurrent

The amount of charge flowing inany conductor is called electriccurrent.

The unit of electric current isthe ampere.

c. resistance The unit of electric resistanceis the ohm.

The resistance of a conductor

. depends upon the materialof which the conductor ismade

. increases as the length ofthe conductor increases

increases as the area ofthe cross-section decreases

-usually increases as thetemperature increases

K-43


/The ampere is defined as one coulomb per

second. If there is a current of one ampere,there are 6.25 x 1018 charges passing a point

in one second.

One volt/ampere is equal to one ohm.

The relationship between voltage and current

may be expressed as V = IR.

This statement, known as Ohm's Law appliesprimarily to metal conductors at a constant

temperature. The law does not apply to elec-trolytic cells, to gas discharge tubes, and

other devices.

KEY WORDS

electric currentampereresistanceohm

REFERENCE OUTLINE

)4 . electriccircuits

a. seriescircuits

*tl) voltage

*(2) current

*(3) resistance

*optional

K .1414


Electric circuits are continuousconducting;paths provided with asource of electricpotentialenergy.

Two types of electric circuitsare series circuits and parallelcircuits.

*One other type of electriccircuit is a combination of aseries circuit and a parallelcircuit.

A series circuit is a circuitwith only one conducting path.

The total voltage across a seriescircuit equals the sum of thevoltages across the components of

the circuit.4

The current in a series circuitis the same at all points.

The total resistance of a seriescircuit equals the sum of theresistances in the circuit.

6kA,CL)

MATERIALS

KEY WORDS

electric circuitseries circuit

K-45

ACTIVITIES

#Although a series circuit contains onlyone conducting path, the path may containseveral components.

Students should be able to draw a simpleseries circuit with several components and beable to recognize a series circuit when seen.

#Characteristics of a Series Circuit

A series circuit may be studied by connectingtwo 10-ohm resistors to a source of voltage(5-6 volts) as shown on the next page. If avoltage source is not available, four dry cellsin series will serve. Spring clip connectorswith attached wires may be placed as shown tomake it easy tn break into the circuit atvarious points. If these connectors are notavailable, alligator clips may be inserted atthe six points with each pair of clips hookedtogether to complete the circuit.

a. Voltage in the circuit. Connect a volt-meter between B and C to measure the voltage drop

across R1.Repeat by connecting the voltmeter

between D and E. To determine the voltage drop

across an entire circuit, read the voltmeterattached to the source or connect a voltmeteracross the terminals. What is the relationshipamong the three voltages recorded?

b. Current in the circuit. Remove the wirebetween A and B. Connect a d.c.-ammeter betweenA and B. Record the reading. Replace the wireand connect between C and D, then between E and F.

Compare the readings. Is charge conserved inthe circuit?

c. Resistance in the circuit. After removingthe wire connection, insert an ammeter betweenpoints A and B. Connect a voltmeter betweenpoints B and C. The meters will give the current

through R1 and the voltage drop across it. Cal-culate the resistance of R1 by using Ohm's Law,V = IR. In a similar manner calculate the

REFERENCE OUTLINE

K-46


MATERIALS

HEY WORDS

K-4-7

ACTIVITIES

resistance of R2

.Calculate the resistance

of the entire circuit by determining the

voltage across both resistors (reading of the

voltmeter attached to the source) and thecurrent through the resistors. How does the

total resistance compare with the slim of the

individual resistances?

SpringClIO

Voltoqe Source

:3f33

K-48

REFERENCE OUTLINE MAJOR UNDERSTANDINGS AND

b. parallelcircuits


A parallel circuit is a circuitin which there are two or moreconducting paths.

'(l) voltage The voltage across each brancha parallel cireuit is the samethe voltage across the source.

ofas

*(2) current The sum of the currents throughbranches of a parallel cicultequals the total current in thecircuit.

the

*(3) resistance The combined resistance of aparallel circuit is less thanthe resistance of any of itsbranches.

*optional

K-4-5


KEY WORDS

parallelcircuit

#Students should be able to draw a simpleparallel circuit with several components and be

able to recognize a parallel circuit when seen.

#Characteristics of a Parallel Circuit

A parallel circuit may be studied byconnecting two 10-ohm resistors to a source ofvoltage (not over 5 volts) as shown on the next

page. If a voltage source is not available, twodry cells in series will serve. Spring clips

may be used at points A through J to permit easy

access to the circuit. If a meter is notconnected between two clips, a wire should beconnected to complete the circuit. If springconnectors are not available, alligator clips

may be inserted with each pair of clips hookedtogether to complete the circuit.

a. Voltage in the circuit. Connect avoltmeter between D and G. This gives thevoltage drop across resistor R. Connect avoltmeter between F and H. This gives thevoltage di.op across resistor R2. Connect avoltmeter between A and J. This gives thevoltage drop across the encire circuit. Compare

the three readings.

b. Current in .che circuit. Remove the coconnecting wire and insert a 0-1 ampere ammeterbetween A and B. Note the reading. This is

the current in the entire circuit. Insert an

ammeter in a similar manner between C and D, andbetween E and F. These readings give the currentsthrough resistors R1 and R2 respectively. Compare

the current in the circuit with the sum of thecurrent in the branches.

c. Resistance in the circuit. Use the three

values of voltage with the three valuesof current just measured to calculate the com-bined resistance of the circuit and the resistancesof the two branches. Is the combined resistance

K-5 0


K


equal to, greater than, or less than theresistance of either branch? Calculate thereciprocals of the three resistances. What is

the relationship between the reciprocal of the

combined resistance and the sum of the recipro-

cals,of the resistances in the branches?

Spring clip 4-Cr)-

U

Vol taqe source

KEY WORDS

REFERENCE OUTLINE

5 electric power

6. electric energy

Magnetism **

A. Magnetic fields

1. detection ofmagnetic fields

a. direction ofmagnetic fields

3. magnetic field ofthe earth

K-52


The rate at which the componentsof a circuit use electric energyis called power.

The unit for electric powe:'the watt.

The electric energy used by acircuit is the product of powerand time. Two units of electricenergy are the watt-hour and thekilowatt-hour.

Magnetism is a phenonmenen exhibitedby charges in relative motion.

Some illagnets are temporary magnets;others are permanent magnets.

Magnetic fields exist aroundmagnetized objects.

One magnetic field may be detectedby another.

The direction of a magncetic fieldis the direction in which the north-seeking pole (N-Pole) of a magneticcompass needle points when in tnepresence of tne magnetic field.

The earth is a large magnet.

The direction of the magneticfield of the earth is shown bya compass needle.

**Pupils may be familiar with the principles of magnetism

from previous science work. Do not repeat unless necessary.

MATERIALS

KEY WORDS

electricpower

wattelectricenergy

kilowatt-hourmagnetism

optional

1c-53

ACTIVITIES

The power consumed by a circuit (in watts)equals the product of the voltage (in volts)and the current (in amperes).

One joule/second equals one watt.

Power -t Volts x amperes

= joules coulombscoulombx second

= joulessecond

Electric appliances are rated in termsof the rate at which they use energy.

Teachers should stress that one pays forelectrical energy not electrical power.

The magnetic properties of substancesare related to the locations and spins ofelectrons in the atom, and to the ease withwhich the electron spins can be aligned. Ironand its alloy, steel, have strong magneticproperties. Nickel, cobalt, and some of their

alloys can be magnetized quite readily.

Steel retains its magnetism longer thansoft iron, and can be used to make "permanent"magnets. A steel knitting needle may be magne-tized by stroking it in one direction withone end of a bar magnet. The strength of perma-nent magnets may be decreased by (1) strikingthem, (2) heating them, or by (3) storing themwith two like poles together.

K,54

REFERENCE OUTLINE MAJOR UNDERSTANDING ANDFUNDAMENTAL COMCEPTS

MATERIALS

KEY WORM)

permanent magnetstemporary magnetsmagnetic fields

K-55

ACTIVITIES

When two or more magnetic fields are inthe presence Of one another, the fields inter-

act. Magnetic fields account for the operationof electric motors, electric generators, theacceleration of subatomic particles, and thepropagation of electro-magnetic waves such aslight and radio waves.

Magnetic fields of permanent magnets maybe studied by placing paper or glass over themagnet and sprinkling iron filings on it. The

iron filings become magnetized and align them-selves with the magnetic fields of the perma-nent magnets.

[Since this phenonemon has undoubtty beendemonstrated on several occastons, a passingreference to it should be sufficient.]

A compass needle on the surface of theearth aligns its N-pole in the direction of the

field. There may be variations due to the near-

ness of certain metals.

A deviation of an ordinary compass needlefrom true north is known as magnetic declination.

A compass needle balanced around a horizontal

axis is called a dip needle. The angle whichthe needle makes with the horizontal, the angle

of inclination, varies with the latitude.

K-56


14. magnetic fieldaround a straightmetal current-carrying conductor

5. magnetic fieldaround a coil

The magnetic field around astraight metal current-carryingconductor is cylindrical.

If a straight current-carryingconductor is bent into a coil,the ends of the coil become magneticpoles.

K-57


#FIELD AROUND CURRENT-CARRYING METAL CONDUCTORS

KEY WORDS

electt±c coil

-Fasten a plecd of cardboand near the endof the table. Connect several feet of bell wire.as shown in the diagram below. Place several smallcompasses on the cardboard near the wire. Closethe switch and note the directions Of the N-polesof the compasses. Reverse the connections on thedry cell. Note the directions of the N-poles.

C=;)

Magneticcompass

5,2(1 wlre

z i rme ghru f

Dry cellSwitch

#THE SOLENOID COIL AND THE ELECTROMAGNET

sk. Connect about four feet of No. 18 insulatedcopper wire in series with a dry cell and switchas shown. Wrap about 1 foot of the wire arounda pencil or wooden dowel to form a coil. Removethe pencil. Close the switch. By means of acompass determine the polarity of the coil. Tracethe direction of the electron flow (-to+) throughthe coil. Wrap the fingers of the left handaround the coil in the direction of electronflow. To what pole does the thumb point? Reversethe connections and repeat. How can the lefthand be used to predict the polarity cf the eletro-magnet?

b. Place a compass about 1-3 inches fromone end of the coil. Note the deflection whencurrent is passing. Add an additional dry cell

in series. Note the deflection of the needle.How does current affect the strength of the pole?

K-58


K-59


c. Connect only one dry cell in series.Note tbe deflection of the compass needle. Windadditional wire around the pemcil as in a previouspage. Place the compass the same distance fromthe end of the longer coil. Note the deflection.How does the number of coils affect the strengthof the pole?

d. Insert an iron nail through the coil.Compare the deflection of the compass needlewhen the nail is in and when the nail is outof the coil.

Soft iron nail Coil

ectrr n fIov

KEY WORDS

Switch

REFERENCE OUTLINE

K-6C1


K-61

AC,TIVITIES

#FORCE ON A CONDUCTOR IN A MAGNETIC FIELD

Suspend a swing of stiff copper wire by hooksso that the swing is between the poles of ahorseshoe magnet as shown. The swing must havegood electrical contact at the hooks and alsobe able to swing freely. Connect a dry celland switch in series. Close the switch. Whathappens to the swing? Reverse the connectionsor reverse the poles of the magnet. What causes

the motions?

ffEFFECT OF MAGNETIC FIELD ON ELECTRON BEAM

The effect of a magnetic field on an electronbeam may be shown by this apparatus. The tube,commonly known as a cathode-ray tube, is availablecommercially. The tube contains a fluorescentscreen which is illuminated when struck by electronsemitted from one of the electrodes. A slit whichis part of the assembly forms a straight beamfrom the electrons emitted by the electode.The bean is visible on the fluorescent screen.

Connect the tube to the sdcondary terminalsof an induction coil which is connected to a6-volt power source or four dry cells in series.When operating a green line will appear on thescreen.

K-62

REFERENCE OUTLINS! MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

K-73


Place a horseshoe magnet over the tube.Note any deflection on the electron beam. Reversethe'poles of the magnet. Is the effect the same?Touch the N-pole of a bar magnet to the top ofthe tube. Repeat with the S-pole of the barmagnet.

An oscilloscope may be used in placeof the cathode-ray tube shown.

0-

E1 Power supply

High voltageSource

KEY WORDS

0

(L-

K-64

REFERENCE OUTLINE . MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

B. Direct currentmotor

optional

#When a current-carryigg loopis placed in a mggnetic field,a force is exerted on the loop.

:3'80

MATERIALS

KEY WORDS

electric motor

K-65

ACTIVITIES

YDIRECT CURRENT MOTOR

An electric motor may be constructed todemonstrate the principle of a current-bearingwire moving in a magnetic field. The motorshown below uses electromagnets instead of permanentmagnets.

8 d. nail

--Cork

--Gloss tubewith fused end

Assemble the armature as the first sbpp.For the bearing, cut a 2-inch piece of 6mm. glasstubing and seal one end in a bunsen burner flame.Drill holes vertically and horizontally througha cork as shown. A size 14 cork with a topdiameter of about 1 1/4 inches is suitable.Insert the glass tube and an 8-penny nail asshown in steps a and b on the previous page.

Wind the armature with No. 20 or No. 22copper magnet wire. Wind botb coildsin the samedirection. Strip the insulation from each end of

the wire and tape as shown in step c.

611;71,

K-66


K-67


KEY WORDS

Drive a 10-penny finishing nail through thecenter of a small board (about 4" x 6") andplace the armature in position. The point ofthe nail in the glass makes a bearing of lowfriction. Drive two 10-penny naild into theboard about 1/8 inch away from the ends thenail of the armature. Each will be about 1 3/4

inch from the center nail. Wind these two nailsin the opposite direction. Use two thumbtacks,small nails or screws to support the ends of thewires which act as bunshes, as shown in thediagram of the motor.

Wire two or three dry cells in series oruse a power pack and connect to the motor. Give

the armature a spin. It may be necessary toadjust the brushes and the wires that touchthe armature.

Determine the polarity of each pole of thefield magnet by a compass or hand rule. Determinethe polarity of each pole of the armature.Account for the turning of the armature.

3

,/

Si mpeMor

K-68


An electric motor transformselectric energy into mechanicalenergy.

384

A-69


KEY WORDS

#THE D.C. MOTOR

Use a demonstration type d.c. motor,

or for individual student work, use small dissectible

motors of the "St. Louis" type. Trace the circuitthrough bfushes, commutator and armature. Removethe field magnet and use a compass to show

the change of magnetic polarity of the armatureas it is rotated. Using the permanent magnetfield, show the effect of field strengbhon the speed of the motor by moving the magnet

away while the motor is running. Change theapplied voltage and note effect on speed.Reverse the connections to the brushes toreverse the directton of rotation. Connect

an ammeter in series with the motor and notethe current when the motor is running fullspeed, and when it is slowed down by a fingerheld against the shaft.

If an electromagnet field is available,operate the motor with field in series andin parallel. Show the method of reversing.

Operate the motor on a.c. supplied by a

small transformer.

3 8 5

K-70

REFERENCE OUTLINE MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCLPTS

C. Induced voltage

*optional

When a metal conductor is movedperpendicular to a magneticfield, or a magnetic field ismoved perpendicular to a metalconductor, an electric potentialdifference is produced (induced)across the conductor.

If this conductor is part of aclosed circuit, there will bea current in the conductor.

When a current is induced, someof the mechanical energy of themoving conductor is transformedinto electric energy.

K-71


KEY WORDS

Make a coil of several turns of insulatedwire. Join the ends of the wire togetherand support the coil as shown in a with asection over a compass. Thrust one pole ofa bar magnel, into the coil and observe theaction of the compass needle. Next hold themagnet motionless in the coil. Now removethe magnet from the coil and observe theaction of the compass. Repeat this prodedureusing the opposite pole of the magnet.

Separate the ends of the coil and connectthe coil to a galvanometer as shown. Repeatthe above steps using the bar magnet and alsoa U-magnet. Note the action of the galvanometerneedle. Hold the magnet stationary and movethe coil. Try moving the magnet or the coil

faster. Use a coil having a different numberof turns. Substitute a weak magnet fo:o a strong

one.

On thp basis of their observations, pupilsshould develop some understanding of the simplerrelationships between magnetism and inducedelectric currents.

:4k3:7

Galvanometerb.

K-72

REFERENCE OUTLINE MAJOR UNDERSTANDINGS ANDFUNDAMENTP L CONCEPTS

K-73


KEY WORDS

#Wind a coil of about 50 turns of No.26 enameled copper wire around three fingersof the hand, wrap it with the free end of thewire to hold the coil in place. Withoutcutting the wire, take three or four feetof extra wire off the spool and wind a similarcoil, leaVing another length for the returnconnection. With the coils in series, hang eachby its own leads just high enough above thetable top to swing freely over the pole ofa strong horseshoe magnet. The points of sus-pension must be the same height so that thecoils acting as pendulums have the same period.

Whietn one coil is set swinging the otherquickly responds. In addition to illustratingelectrical relationships, this experiment canbe used to help establish the concept of re-sonance. It is instructive to revers,: thepolarity of one of the magnets and discussthe result.

9

K-74


III. Light Light is a form of energy.

A. Electromagneticradiation

Light is electromagnetic radiationthat produces the sensation ofsight.

Energy transferred thrcugh avacuum (free space) travels inthe form of electromagnetic waves.

1. sources Electromagnetic radiation mayarise from

accelerating electrons in anelectric field or circuitelectric dischargesincandescent objects

MATERIALS

KEY WORDS

lightelectromagneticradiation

K-75

ACTIVITIES

#BETECTION OF ELECTROMAGNETIC RADIATION

a. Assemble the apparatus as shown in the

diagram below. The switching mechanism is an ironsaw blade and a stiff piece of copper wire. Drawthe wire across the saw blade to make and break thecircuit rapidly. Observe any change in the neonlamp.

The dry cell supplies the energy to acceleratethe electrons originally. A magnetic field buildsup in the vicinity of the coil connected in seriesto the dry cell. =aen the switch is open, thecurrent oscillates Ghrough the coil with themagnetic field building up and decaying alternately.Energy loFt by heat is replaced by the cell whenthe switch is again closed.

10-100 rnmf

(ISO turns*?4 wire

NE-2

b. Oonnect an induction coil to a 6-voltsource. Place an operating A-M radio near the

points of the coil where discharge occurs. Is

there any evidence of radiation during discharge?

c. Heat a piece of copper wire in the flameof a bunsen burner until the wire glows. Removeand place the wire near the hand. Is there evidenceof two kinds of electromagnetic radiation?

r3q1

K-76

REFERENCE OUTLINE MAJOR UNDERSTANDINGS ANDFUNDAMENTAL cONCEPTS

2. characteristics All electromagnetic radiation isa form of energy.

a. frequency The number of waves passing a pointin a untt of time (sedond) is thefrequency of the waves.

Frequency may be expressed in cyclesper second or hertz.

b. wavelength The distance from one point in awave to the corresponding pointin the next wave is the wavelength.

Wavelength may be expressed in anyunit of lenghti.

c. speed Electromagnetic radiation travAl#in a vacuum at a speed of 3 x 10ft

meters per second (300,000 km/sec)or 186,000 mi/sec.

e-N 2

K777


Common examples of evidence that lightis energy are photographic light meters (lightenergy to electric energy) and photosynthesis(light energy to chemical energy).

Recently the term "cycles per second" hasbeen given a name, "hertz". MMny recent publicationsuse this term. For example, 20 cycles per secondare 20 hertz.

The color of lIght depends upon the frequencyof the wave,

Wavelengtki of light is usually expressedin Angstroms (A). An Angstorm is 1 x 10-10meter or 1 x 10-8 centimeter (0.00000001 cm).

The speed of a wave is the product of itsfrequency and wavelength.

Since electromagnetic waves in a vacuumall travel At the speed of light, the equationis written as c=zfA, where c is the speed ofliOat and A is the wavelength/

KEY WORDS

frequencyhertzwavelength

REFERENCE OUTLINE

3 classification

B. Intensity andillumination

1. path oflight

2. illumination

K-78


Electromagnetic waves are classi-fied according to their wavelengths:

electric wavestelevision and radar wavesmicrowaves and radarinfraredvisible iight

t.t tatrivieietgamma rays and x-rayscosmic rays

The electromagnetti spectrum con-sists of all frequencies of elec-tromagnetic radiation from thoseradiations with very long wave-lengths to those with very short

wavelengths.

The visible light portion of theelectromagnetic spectrum is relativelynarrow.

The amount of light falling on asurface (illumination) depends onthe intensity of the source andthe distance that the surface isfrom the source.

Light travels away from a sourcein straight lines.

The amount of illumination on asurface decreases as the distancebetween the source and the surfaceincreases.

K-79


Supplementary InformationFor Teachers

It is important to pointout that biaere is no definitedividing line between "adjacent"categories of electromagneticradiation. The chart of thespectrum shown represents onlyapproximations.

[Pupils should not be expectedto memorize the approximatefrequencies or wavelengthsof these radiations.]

It is particularly importantto point out that only asmall portion of the spectrumcan be directly detectedby 1-1e. eyes. Other devicesmust be used to detect radiattonsnot -.risible to the eye.

KEY WORDS

electromagneticspectrum

THE ELECTROMAGNETIC SpECTRUM

yowl 1P4014 1117CGD(NDY

(C.) (s01)

5X 10-" 102'

to°axto-* to"3 X10-2 102

1.1 X10-1 to't5810-I to'l5xlcrsstcto-4 to"uttr* to'*51i0-1 lost3xto-' to"uto ° to°szte, ' to

5810 2 10

3/110 3 10 7

58 10 10

5810 5 10 5

5%10 10'3 X10 1 10 3

3%10 10 2

3X10 10

CO.SM1CRAYS

GAADAA DAYSX DAYSh. rd)

)(DAYS0.110

t-

REFERENCE OUTLINE

K-80


;RIALS

WORDS

K-81

ACTIVITIES

INTENSITY OF ILLUMINATION

Allow light from a small hource (such

as a "germ of wheat" lamp) to pass througha pinhole in a cardboard. (This simulatesa point source of light.) Place a screen ata measured distance from the pinhole. Determinethe diameter of the spot of light and computethe area df the spot. If a light meter isavailable determine the reading. Double andtriple the distance from the source. Makesimilar-measurements. Does the area of thespot change as the distance from the source(pinhole) c.anges? If so how? Does theintensity of illuminaticn change? If so, how?

A light meter placed in front of anautomobile headlight will not illustratethe inverse square law since the light isnot a point source. Acutally, the virtualor apparent source of light which has beenreflected by a mirror is several feet behindthe headlight.

1<-82


C. Reflection oflight

When a beam of light strikes asurface, some light will bereflected and some will beabsorbed and some may be trans-mitted.

1. laws of Two laws wisociated with reflec-

reflection tion of light are:

When light rays strike (are

incident upon) a reflectingsurface, they are reflectedin the same plane as the in-cident rays.

When light strikes a surfaceand is reflected, the angleof incidence equals the angleof reflection.

K-83


Supplementary Informationfor Teachers

If an optical disk is used, the lawsof reflection may be illustrated quiteeasily.

Certain reflecting surfaces, such asmirrors, reflect the image of the objectproviding the incident light. This is knownas specular reflection. Other reflectingsurfaces are irregular, and light is reflectedin magY different directions although thelaws of reflection apply to each ray of ligrit.This is known as diffused reflection. Diffusedreflected light is particularly good forreading since it reduces shadows.

When light is reflected by a planeemirrorto "form" an irnage, the reflected rays appearto have come from behind the mirror. Thisis where the virtual image appears to be.Since it is impossible for the rays of lightto pass throggh the mirror, no image will beformed on a screen placed where the imageappears to be.

KEY WORDS

ReflectionAngle of IncidenceAngle of Reflection

REFERENCE OUTLINE

K-84


00

MATERIALS

KEY WORDS

K-85

ACTIVITIES

#Vital Nature of Plane Nirror Image

A very instructive and entertainingillusion may ae assembled with two candlesand a pane of window glass. The candles,as nearly identical as possible, are mountedon opposite sides of the vertical piece of

glass. The rear candle is carefully placedat the position of the image of the frontone formed ty the glass. When only thefront candle is burning, both appear to belit, the virtual image of the flame appearingon the unlit candle. The glass plate mustbe large enough so the image can be seenfrom all parts of tne classroom. The instructorcan hold his finger in the "flame" of therear candle without burning it, or expounda new method of "fireprodftagg" paper. Whenthe rear candle or the glass is moved, thefact that only one candle is lit Is immediatelyobvious. When the illusion is adjusted for bestcoincidence of candle and image, the objectand image distances to the reflecting surfacecan be measured and of course will be equal.The fact that the image and object lie on aline perpendicular to the glass and that theimage is virtual, erect and the same Itzeas the object should be noted.

Wor an amusing variation, mount the unlitcandle in a beaker, and pour water into it.Finally the flame appears to be under water.

4 0 1

K-86

REFERENCE OUTLINE MAJOR UNDERSTANDIYJS ANDFUNDAMENTAL C0147PTS

D. Refractionof light

E. Color

1. reflection

2. -6ransmission

A light ray moving obliquely fromone dedium to another is refractdd(bent)

The color of light depends uponthe frequency (or wavelength) ofits waves.

The color of light reflected from

a surface depends on the color of

the incident light and the natureof the reflecting surface.

The color of light transmitted bytranspa:cent materials is C.eterminedby the color of the incident lightand the vavelengths of light towhich the materials are transparent.

402

K;-87


KEY WORDS

refractioncolor

#REFRACTION OF LIGHT

a. Pupils can easily observe refractionof light if an optical disk is used. Allowa fine pencil of light to pass obliquely frcm

air into glass. Observe the bending of lightas it enters and leaves the glass.

b. Place a rectangular pi.ece of glassabout 1/2 inch thick on a tablet. With apencil draw the outline of the glass. Placepins A and B in the tablet so that a lineconnecting the points would strike the glassobliquely. Place your eye close to the tableand sLO-It throuch the opposite side of theglass at pins A and B. Place two additionalpins so that all four pins appear tc be onthe same line. Remove the plate. Extendlines AB and CD to the edge of the plate.Draw line BC. Construct perpendiculars atB and C. Note the bending of the light rayas it entered and left the glass.

4.03

REFERENCE OUTLINE

K- 8 8


MATERIALS

KEY WORDS

K --f39

ACTIVITIES

# REFLECTION OF LIGHT

Place several objects in the path of abeam of light. Objects suggested are paperof various colors, colored glass or cellophane,cardboard with surfaces of varying smoothness,and sheets of assorted metals. Note differencesin the amount of light reflected, color reflectedand whether your image can be seen when lookingat the surface. Can you make any genealizations?

White Light is called polychromaticlight beaause it is composed of many colors(different frequencies or wavelengths.) Ligbtof each different color is slcwed down differentlyas it moves from air into a more opticallydense medium. When white light passes obliquelyinto prism, each color is refracted differentlyand is separated.

The prism spectroscope, operating onthe principle of the dispersion of light,is used to iden,.;ify chemicals.

Probably the topics of the color ofreflected and transmitted light have beenpresented in previous years. Only a briefreview should be necessary here.

The wavlengths of light which are reflectedfrom a surface depend upon the material ofWhich the surface is composed. If the atomsin the surface are such that they will acceptenergy from incoming wavelengths of light,then those wavelengths will be absorbed.The other wavelengths will be reflected.

K-90


IV. Sound*Sound is a form of mechanicalenergy.

Sound is a periodic disturbancein an elastic medium.

*Sound reauires a medium throughwhich to travel.

A. Sources Sound is produced by vibratingmatter.

B. Characteristics ofsound waves

The properties of sound dependupon the characteristics of itswaves.

1. type *Sound travels in longitudinal(compressional) waves.

2. frequency

3. wavelength

*optional

As longitudinal waves move througha medium, the molecules of themedium are alternately closertogether (condensations) andfarther apart (rarefactions)than when in the rest position.

The frequency of a sound wave isthe number of vibrations of itsparticles each second.

*The frequency of sound waves isless than that of light waves.

The wavelength of a sound wave isthe distance from one condensationto the next condensation.

4nts

MATERIALS

KEY WORDS

SoundLongitudinal Wave

Kr-91

ACTIVITIES

#TRANSMISSION OF 'SOUND THROUGH A MEDIUM

Place a bell jar with an operting on thetop on a pump plate. Connect a bell in serieswith a switch and dry cell by means of wirespassing through a rubber stopper. Placethe stopper securely in the top of the belljar. Close the switch. Note the loudnessof the sound caused by the bell. Evacuatethe air from the bell jar by means of a pump.How does the loudness of the sound change?

407

K-92


MATERIALS

KEY WORDS

K-93

ACTIVITIES

#LONGITUDINAL WAVES

Suspend a coiled screen door spring ora "slinky" between two upright supports sothat the spring is slightly extehded. Tie

strings at regular intervals along the springto give additidmal support.

Pinch together a few coils at one endof the spring and release. Note the motionof the pulse and its reflectIon from theend of the spring. Repeat by alternatelyc-mpressing and releasing thespring. In

what direction do the parts of the springvibrate? Compare the direction of vibrationwith the direction of wave motion.

Rod or rout cable oder orislosq-'nay bit rodIrdoed O.eirn or ceiling

Millievittfili1WRing srond end clomp String for. free Cdpen) end

fo fixed (e1e3cd) end

The pitch sound depends upon the frequencyof the sound wave.

K-94


Kr-95


The frequencies of sounds emitted bymusical instruments may be changed by changingthe lengths of air columns or strings.

Sound is often defined as a diSturbancethat can be detected by the human ear. Althoughthere are individual variations, sound dan behhard If the frequency of its wave is betweenapproximately 20 cycles per second and 20,000cycles per second. If the frequency is below20 cycles per second, the sound is calledinfrasonic. Frequencies over 20,000 cyclesper second produce sound that is known asultrasonic.

KEY WORDS

REFERENCE OUTLINE

4. speed

5.- amplitude

C. Reflection

D. Resonance'.

X-96


*The speed of sound in air at 0°C.

is approximately 331 meters persecond (1090 feet per second.)

The loudness of a sound dependsupon the amplitude of a soundwave.

*Sound waves may be reflected.

A source of sound may cause anobject to vibrate if the Vibrationrate of the object is the same asthat of the source.

419

MATERIALS

KEY WORDS

AmplitudeResoaance

K-97

ACTIVITIES

*The speed of sound in air increasesabout 0.6 metere per second (or 2 feetper second) for every Celsius degree increasein temperature.

*If a sound wave Is reflected back tothe ear in a time greater than 0.1 second,a separate sound is distinguished which isknown as an echo.

Interesting applications of thereflection of sound involve whisperinggalleries, parabolic microphones to pickup crowd noises, and sonar.

# RESONANCE

Obtain two tuning forks of the amme frequency.Strike one fork and place both forks on a tableseveral feet apart. After several secondsstop the Vibrationof the first tuning fork.Can you determine if the second fork is vibrating?(If resonance boxes are attached to the twotuning forks, the results are more obvious.Place the boxes so that the open ends faceeach other.)

4-13

REFERENCE OUTLINE

K-9 8

MAJOR UEMERSTANDINGS ANDFUNDAMENTAL CONCEPTS

K-99


KEY WORDS

Actually resonance will occur if thenatural vibration rate of the object is amultiple of the vibration rate of the source.

Resonance may he likened to pushing achild on a swing. A small force appldedat the proper times will increase the ampli-tude of the swing.

An outstanding example of resonance is thedestruction of the Tacoma-NarrOws Bridge in1940 which began to cscillate due to thefrequency of gusts of wind.

415

K-100

REFERENCE OUTLMNE MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

V. Heat and Its Effecton Matter

A. Heat Heat is the total kinetic energyof all the molecules in a substance,

1. heat transfer Adding heat to a substance increasesthe total kinetic energy of alltbe molecules in the substance.

Removing heat from a substancedecreases the total kineticenergy of all the molecules inthe substance.

2. measurement of Heat may be measured-, in MKS units

heat call kilocalories.

B. Temperature

1. measurement oftemperature

The kilocalorie is the heat requiredto raise the temperature of onekilogram of water one Celsiusdegree.

Temperature is a property ofbodies that determines in whichdirection heat will flow whenthe bodies are in contact.

When two bodies are in contact,heat will flow from the body ofhigher temperature to the bodyof lower temperature.

The temperature of a body isstated in comparison to somestandard temperature.

K-l0l


KEY WORDS

HeatkilocalorieTemperature

*optional

Substances such as a block of wood, aquart of water, or a cubic foot of gas, arecomposed of particles which are moving. The

particles have kinetic energy due to their

motion.

The kilocalorie is equal to 1000 calories.

Food iS often described as having a nambe±nnumber of calories. This means the heat energyavailable when the food is oxidized. The Calorie(large calorie) is the kilocalorie.

In the English system the unit of heatenergy is the British Thermal Unit (B.t.u.).The B.T.u. is the heat required to raise onepound of water one Fahrenheit degree. TheB.t.u. is often used to indicate heat energyavailable from fuels.

It is very difficult at this level togive a good definition of temperature.Temperature may be defined as being dbblermined

by the average kinetic energy of the molecules.Another definition of temperature is that propertyof a body that is measured by a thermometer.

Since heat and temperature are ae closelyrelated, it is suggested that both be discussedat the same time. Hew@Ver, it should be madeblear that temperature and heat are not the

same.

A comparison that may help to distinguishheat and temperature is: Temperature is to

heat as water pressure is to the amount of

water.

-417

K-102


2. thermomet6i.

Two common standard temperaturesare the boiling and freezingtemperatures of water at oneatmosphere of pressure.

The boilinR point and the freezingpoint of water are often referredto as the fixed points on a thermometerscale.

A thermometer is a device to indi-cate temperature in relation toa certain standard temperature.

Many thermometers operate an theprinciple of the expansion andcontraction of solids, liquidsor gases, with increases or de-creases in temperature.

a. Celsius scale The fixed points on the Celsiusscale are 0 degrees and 100 degrees.

b. Fahrenheit The fixed points on the Fahrenheit

scale scale are 32 degrees and 212 degrees.

MATERIALS

KEY WORDS

thermometerCelsiusFahrenheit

K=193

ACTIVITIES

#TEMPERATURE IS RELATIVE

Three 500-ml. beakers can be used todemonstrate that temperatures are relative.One beaker is half-filled with water at roomtemperature, the secoBd beaker is half-filledwith water at 100-120 F., and the third beakeris half-filled with a mixture of ice and water.Have a student place one hand in hot water andthe oteer in ice water for 1-2 minutes. Remove

the hands and place them in the water at roomtemperature. Is the water at room temperaturehot or cold? In which direction do you think

heat is flowing in each case? Is the body

a good thermometer?

30'

419

REFERENCE OUTLINE

it-104


MATERIALS

KEY WORDS

K-105

ACTIVITIES

# TELIBRATION OF A THERMOMETER

Place a mixture of ice and water in a

beaker. Insert an unmarked mercury or alcohol

thermometer. After the reading becomes constant,

mark the location of the reading.

Place about 2 inches of water in an Erlenmeyeror Florence Flask. Suspend the thermometerso that its bulb is about 1 inch above the surface

of the water. Heat the water to boiling. Mark

the location of the liquid in the thermometerwhen the reading is constant.

MixtureoF iceand

water

0.0 Point-

Asbestosscreen

K-106

REFERENCE OUTLINE MAJOR HNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

K-107


KEY WORDS

The type of thermometer used at a giventime depends in part on the temperature to bemeasured. A mercury ther9ometer cannot be used

at temperatures below -39 C., the approximatefreezing point cf mercury.

In some applications the temperature of aglowing object may be obtained from its color.

An optical pyrometer is used for this purpose.In still other instances, temperature may be

measured electrically. A tl-ermocouple is adevice to measure temperature in this way.

Thermometers are calibrated by determiningtwo fixed points and dividing the distancebetween the points into a desired number ofequal parts. Between the fixed voints the

Fahrenheit scale has 180 degrees while theCelsius (formerly Centigrade) scale has 100

degrees. The divisions may be extended beyondthe fixed points in either direction.

423

REFERENCE OUTLINE

C . SOURces of heat

K_106DAAHeat

rief 5ot 3T

derived 4,f,k.ifce fierg3t 9 sk4e'll-

rneet e

e1e eriefaCrielniceA enefgy

nuclear' ilerg3T

K-109


KEY WORDS

# TRANSGfiRMATION OF MECHANICAL ENERGYTO HEAT ENERGY

Place water in a 500-ml. beaker or othercontainer until the container is about half

full. Determine the tempenatdre of the water.

-Remove the thermometer. Beat the water for oneminute with a manually-operated egg beater

(or an electric egg beater borrowed from the

home economics department). Determine the

temperature. Account for any change in temperature.

Has the thermal energy of the water increased?

#T2RANSFORMATION OF ELECTRIC ENERGY TOHEAT ENERGY

Connect a 10-ohm, 5-watt resistor in series

with a power pack. Place about 100 grams uf

water in a beaker. Determine the temperatureof the water. Place the resistor in the water

and connect the power pack to a voltage source.Set the output for about 6 volts. (If a power

pack is not available, use four dry cells connected

in series). After about one minute determinethe temperature of the water. Has the temperature

increased? Has the thermal energy of the water

increased?

This experiment may be conducted quantitativelyby a few pupils using more elaborate apparatus.The container of water should be insulated.The voltage and current across the resistorshould be determined by appropriate meters.The method for calculating the heat gainedby the container is found in most physicstextbooks. Pupils shotld be able to dEbtermine

a relationship between electric energy and heat

energy.

K-110


D. Transmisston ofheat energy

1. donduction

2. convection

Heat may be transferred from abody of higher temperature to abody of lower temperature by con-duction, convection, and radiation.

Conduction is the transfer ofheat from particle to particleT/Tithin a body.

Metal'S are usually the best con-ductors of heat.

Substances which conduct heatslowly are known as.heat insulators.

Convection is the transfer ofheat through liquids and gases bymeans of currents.

Convection currents transfer heatthrough the waters and atmosphereof the earth.

3. radiation Radiation transfers heat by infra-red electromagnetic waves.

Radiant heat travels at a speed of3x10u meters oer second (186,300miles pr second).

The heat which the earth receivesfrom the sun is transmitted throughspace by radiation.

4?8

K-111

MATERIALS ACTIV1TEES

KEY WORDS

conduction

# HEAT TRANSFER BY CONDUCTION(Do not repeat unnecessarily)

Place one end of a metal bar or wire inthe flame of a bunsen burner or near anotherheat source. Place your fingersat the otherend of the metal. Is a temperature rise noted?

The investigation can be made more quantitativeby heating various solids (including metals)of equal detmensions (length and cross-sectionalarea) and noting the time for a given increasein temperature at the other ends. Bits ofwax are often placed at the opposite ends.How does wax serve as a temperature indicator.Which substances conduct heat most rapidly?Least rapidly?

427

K-11-2


428

K-113


KEY- WORDS

convection

# HEAT TRANSFER BY CONVECTION(Do not repeat unnecessarily)

Place approximately 400-ml of water in a500-ml. beaker. Set the beaker on a tripod.Apply heat to the center of the bottom of thebeaker. Add two or three crystals of potassiumpermanganate or two or three drops of ink tothe water. Note the direction of the currentsas shown by the movement of the coloring material.

Open a refrigerator door. Check the motionof currents using smoke or by threads heldin the hand. Have pupils hold thermometersabove and below the open door to note anychange in temperature.

429

K-114


K-115

ACTIVITIES

# TRANSFER OF HEAT BY RADIATION

Have pupils hold their hands about 6 inchesabove, below and to the tide of an operatingelectric iron. Can convection account for any

transfer of heat below and to the side of theiron?

Use a triangular prism to disperse lightfrom the sun or some other intense source of

heat and light. Hold a thermometer for aminute in the blue, yellow, and red portionsof the spectrum. Is there any temperaturerise? Hold the thermometer in the dark areabeyond the red. What effect, if any is noted?

White light

An interesting "recent" application ofthe use of infrared rays is infrared photography.Photographs taken with special film revealdifferences in ground cover anddthe locationof cities by differences in heat radiated from

various objects. This technique has importantmilitary and civilian uses.

431

IC --116


MATERIALS

KEY WORDS

solidliquidgasmelting pointfreezing pointboiling pointcondensationpoint

expansioncontraction

K-117

ACTIVITIES

# TEMPERATURE AND CHANGES OF PHASE

Have pupils place crushed ice into a 150-ml.

beaker. Support a thermmmeter so that itsbulb is buried in the crushed ice. At.one-minute intervals, have the pupils read andrecord the temperature and note the state(s)of matter seen in the beaker at the time ofeach reading. Continue to take the temperatureafter the ice has changed to water.

The data should be graphed with temperatureon the 2*Axis. The graph will be a horizontalline during the change of phase since any heatabsorbed by the ice is used to rearrange themolecules for the liquid phase. After all theice has melted, the temperature will rise ata fairly uniform rate. Details of the latentheat of fusion can be found in physics textbooks.

The time required for this activity can bedecreased by setting the beaker of ice in adish of hot water.

Have pupils account for the change in theslope of the graph.

The energy being absorbed or liberatedduring a change of phase is involved with theparticles adjusting themselves to the newconditions necessary for the new phase. Primarily,it is a shift of potential energy since theconstant temperatuve indicates that the averagekinetic energy of the particles is remainingconstant.

It is not necessary for pupils to learnthe boiling and freezing points of any substanceexcept those for water.

As the pressure on alliquid increases,the boiling point increases.

REFERENCE OUTLINE

F. Phases of matter


Matter may exist in the solidphase, liquid phase, and gaseousphase.

The phase in which matter existsdepends on how close together itsparticles are and how fast theymove.

When a change of phase occurs,energy is either absOrbed orliberated.

1. melting point A. pure solid has a definite temperature

and freezing called the melting point, at which

point it turns into a liquid.

2. boiling pointand condensingpoint

A liquid changes into a solid ata temperature called its freezingpoint.

The melting and freezing pointsof a substance are the same underthe same pressure.

It is possible for a substance toexist as a solid and liquid at thesame temperature.

A pure liquid becomes a gas at adefinite temperature called theboiling point. The boiling pointis usually recorded at one atmosphereof pressure.

A gas condenses into a liquid atthe condensation point.

The condensation and boilingpoints of a given substance arethe same temperature under thesame pressure.

K-119


KEY WORDS

435

K-120


F. Expansion andcontraction

Matter generally expands as itabsorbs heat and generally con-tracts when heat is removed fromit. (A notable exception to theseeffects takes place in waterbetween 00 C. and 4° C

G. Conservation of When heat flows from one body toheat energy aaother, the heat lost by the

warmed body is equal to the heatgained by the cooblr body.

4774,Z

K-121


KEY WORDS

BLOCK L

LIVING WITH THE ATOM

4!'-48

K-1

BLOCK L - LIVING WITH THE ATOM

INTRODUCTION

Radioactivity

nuclear reactionsnature of radiationsdetection of radioactivityrate if decal- - half life

Induced Radioactivity

Nuclear Fission

chain reactionsuncontrolled reactionscontrolled reactions

Nuclear Fusion

Uses of Radioactive Isotopes

chemistrybiologymedicineagriculturearcheologyindustry

Radiation Safety

effects of radiationeffects of nuclear exnlosionsphysiological effects of radiationprotection against effects of nuclear explosions

Important concepts are indicated by a dagger (+). Materialsconsidered of an enrichment nature are indicated by an asterisk (*).

419

L-2


I. Radioactivity

A. Particles

Radioactivity is an atomicproperty and is independentof the state of chemical com-bination.

Radioactivity is an effect oftransmutation with emission ofalpha and beta particles.

Alpha particles are positivelycharged helium nuclei. Betaparticles are negativelycharged electrons.

When an atom is bombarded by alphaparticles, scattering occurs givingevidence of the presence of anextremely small, positively chargednucleus and much empty space.

It was proposed that when radio-activity is occuring, heavieratoms are breaking down intolighter atoms and are giving offsome energy in the form ofradiations.

Information obtained from x-raysmade it possIble to arrange elementsin a table according to theeir

atomic numbers.

440

L-4

REFERENCE BUTLINE MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

Some symbols commonly used torepresent nuclear particles are:

1proton H

1

electron e-11

neutron n

alpha 4

particle He2

gamma ray Y

2

deuteron H1

The lower number (subscript) repre-sents the charge or the atomicnumber. The upper number (super-script) represents the mass.

442

MATERIALS

filing cardelectroscopetimerbeta sourcerubber rod

KEY WORDS

alpha particleatomicbetadeuteronelementsemissionnucleusnuclearpropertyradioactivitysymbolstransmttation

L-5

ACTIVITIES

Charge an electroscope so that its leavesdiverge 900 and measure the time that elapsesuntil the divergence is reduced to 45°. Nowcharge the electroscope again so that its leavesdiverge 900 and suspend a radioactive beta sourcenear the ball at a distance of 2 or 3 cm. Measurethe time required to discharge the electroscopeto the same point as before.

To measure divergences of 450 and go° withreasonable accuracy, fold over the corner of afiling card as shown in the diagram and cutalong the fold with a scissors. A small righttriangle remains. Sight across the right anglecorner of the triangle and adjust the chargeof the electroscope until the diverged leavesare in line with it. Sight across one of the45° angles of the triangle until the electroscopeis discharged to that point.

Leavescometogether

Timer

443

L-6


B. Isotopes +Atoms of the same element alwayshave the same number of protons inthe nucleus.

+Atoms of the same element may havedifferent numbers of neutrons inthe nucleus. These atoms of thesame element with different massesare called isotopes.

Isotopes of a given element occupythe same place in the periodic table.

Many isotopes are unstable andbreak down spontaneously emittingatomic radlittthnns These unstableisotopes are called "radioisotopes".

Isotopes of an element have thesame chemical properties but dif-ferent masses. The chemical prop-erties are the same number of elec-trons outside the nucleus. Theseelectrons are involved in chemicalreactions.

Although there are only about 103different elements, about 280 stableisotopes exist in nature. Man hasbeen able to make an additional800 or more isotopes -- most ofwhich are unstable and radioactive.

+The location of unstable isotopesmay be determined by detecting theradiations they produce.

All isotopes with atomic nubbersgreater than 83 are radioactive.

444

MATERIALS

KEY WORDS

detectingisotope

L-7

ACTIVITIES

Atoms of the same element may vary in massbecause of different numbers of neutrons withinthe nucleus. These different atoms of thesame element are called isotopes. Isotopesof an element contain the same number of protonsbut a different number of neutrons. Isotopesof the same element have similar chemical properties.

The chemical properties of the isotopes arethe same since the number of orbital electronsis identical for isotopes of th8llsgmn,e16m0Attive(Inethiaauase of the isotopes 6f hydrogen, distinctivenames have been given to each isotope. This isa unique situation. In other cases the isotopesare identified by their mass number such asU-235 and U-238).

Use the isotopes of hydrogen to illustratethe huclear structure tf a series of isotopesas zglauWn on the following diagram:

000*drown Mass DEIITEURIII/77 7R/7711/71hydrogen Mass Hydrogen Mass

2isotopes of Hydrogen

445

L-8


L-9


KEY WORDS

massesperiodic tablespontaneouslyunstable

Listed are some common isotopes, some ofwhich are radioactive. Have pupils determinethe difference in nuclear structure of thefollwing series of isotopes and identify themore stable isotope in each series. What determineswhich one of the isotopes is considered the"more" stable? (Its mass is usually closestto the average mass of the isotope given inthe periodtc table.)

39 4019X 19X

16 187080.12c 136 6C

59, 6027w 27Ccs

41 3119X 15P 32P 34PIS IS180 273Ra 224Ra 226Ra

8 88 88 8814 233u 23Su 238C6 92 92 92U

Establish specific lists of isotopes andtheir applications in medicine, industry, agriculture,food preparation and preservation, etc.

447

REFERENCE OUTLIER

C. Nuclear Reactions

1. Radioactiveatoms

L-10


+The nucleas of an atom may bestable and therefore give offno radiations. The nucleus ofan atom may be unstable and giveoff radiations. This type ofnucleus is said to be radioactive.

+Some atoms are naturally radioactive.

+Some atoms can be made radioactiveby bombarding them with particles.

some particles which are used tobombard atoms arecneutrons, pro-tons, and alpha particles.

+Radioactive atoms emit particlesand/or other forms of radiation.

The emissions of radioactiveatoms include protons, neutrons, bebeta particles, alpha particles,and energy in the form of gammarays.

448

MATERIALS

KEY WORDS

L-11

ACTIVITIES

THE NATURAL RADIOACTIVE SERIES

Three series of naturally radioactiveisotopes are known: the uranium-238; thethorium series; and the actinium pr.uranium-235series. Anbbher series, the neptunium-237,has been produced in the laboratory. The Np-237series with a half-life of 2.2 million yearsit too short to enable this series to sustaAnitself over the age of the universe, 4 x 10 years.

CHARACTERISTICS OF NATURAL RADIOACTIVE ISOTOPES

Name ParentNuclide

Stable endproduct

Half-life ofparent nuclide

Thorium Th-232 Pb-208 13.9 x 109yrs.

Uranium U-238 Pb-206 4.5 x 109.yrs.

Actinium U-235 Pb-207 0.71 x 109yrs.

449

L-12

REFEREN CE OUTLINE MAJOR UNDERSTAND IN GS ANDFUNDAMENTAL CON CEPTS

MATERIALS

KEY WORDS

bombardemitgamma rays

L-13

ACTIVITIES

DECAY OF ISOTOPES

Many isotopes are unstable and break downspontaneously emitting atomic radiations. Manyof these radioactive isotopes are useful toman in industry, agriculture,aandmmddicine.

Decay of Isotopes Use

6C - 7N + -e1Carbon datingPhotosynthesis research

14 14 o

59 o o Friction and lubrication59Fe - 27Co + -1

e + oy

26 studies

131 131 o o Thyroid gland physiology

53I - 54

Xe +-1e +

oy

60 60 o o Cancer treatment

27Ce 28Ni + -le + oY Measuring liquid heights

198 198" o o Cancer treatment

7sAu -0.- na + e * y

32p 32s o o...

IS 16 -1 o1

Agriculture research

L-14


2. Mass-charge +If a particle is added to a nucleus,

relationships the mass of the nucleus increases.

+If a nucleus emits a Particle, themass of the nucleus decreases.

+A new kind of atom is made when anucleus gains or loses a particle.

*The changgtggof one itlement intoanother element or isotope isknown as transmutation. Transmutationmay be represented by nuclearequations.

*Tn nuclear equations the sum ofthe atomic numbers (or changes)is the same on each side of theequation.

*In nuclear equations the sum ofthe mass numbers is the same oneach side of the eauation.

42

MATERIALS

KEY WORDS

atomic numberequation

L-15

ACTIVITIES

MASS-CHARGE RELATIONSHIPS IN NUCLEAR EQUATIONS

Nualear equations indicate the particles,masses and charges involved but normally do notindicate energy changes. In writing nuclearequations, the subscriots indicate the chargeswhile the superscripts indicate the masses ofthe particles. In the case of atoms, thesuperscript indicates the charge ithich is equalnumerically to the atomic number.

The sum of the superscripts on one side ofthe equation equals the sumeof the superscriptson the othhr side. Similarly, the sum of thecharges on one aide of the equation is equalto the sum of the charges on the other.

Pupils should be given the opportunity towrite nuclear equations. One example of anuclear equation deals with neutron bombardment.Normal nitrogen is bombarded by a neutron toproduce radioactive carbon-14 and the emissionof a proton. The complete equation is:

14 1n0

7

IH1

(nitrogen) + (neutron) (carbon-14) + (proton)

Note that the sums of the superscripts are equal,

-phat 14 + 1 = 14 + 1. Alsonnotethe sums ofsubscripts are equal, that 7 + 0 = 6 * 1.

A good teaching technique is to writeimcomplete equations and have the pupils determineone particle that has been omitted. An example is:

Complete the equationo

4

The pupils determine from the sume of the super-scripts that the mass of the unknown particle is

14. Similarly, the charge (or atomic number) must

be 6. The periodic table indicates that the atomwith an atomic number of 6 is carbon. Therefore,the missing term is 14 -

4536

REFERENCE OUTLINE

10=i0

MAaOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTSFUNDAMENTAL CONCEP7J

MATERIALS

KEY WORDS

mass-chargemass-numberrelationship

optional

11=1g

ACTIVITIES

NATURAL RADIOACTIVITY

There are two general types of nucleardisintegration: induced radioactivity-andnatural radioactivity. Induced radioa.ctivityresults when stable nuclei are subjected tobombardment by other particles. Natural radio-activity refers to the decay of naturally occuringunstable isotopes.

One series of natural radioactivity is thedecay of U-234 to stable lead. The equationsgiven below do not show the rate at which thedisintegration proceeds nor the emission ofenergy...only. the end products are given:

234 230 492U .4' 90Th + 2}1°

230 490Th -6.

226Ra + 2He88

22688Ra -I-

222Rn + 4He86 2

4222Rn-I-

218Po-

21482Pb + 2He86 84

214pb 214Bi Oe82 83 -1

214 - 1 483131 -I

20- 81T1 + Pe

0210T1 - 21082Pb + -le81

210 0210pb83Bi + -1e82

210 - 210 083B1 - 84Po + -le

210Po-

2066. 82Pb +

4He84 2

Note that when an alpha particle is emittedT themass of the original atom is decreased by 4 andits atomic number decreased by 2. When a negativebeta particle is emitted, the mass remains(essentially) constant and the atomic number isincreased by 1.

455

L-18

REFERENCE OUTLINE MAJBEI UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

496

MATERIALS

KEY WORDS

L-19

ACTIVITIES

THE DISINTEGRATION OF URANIUM-238 SERIES

Radioactive disintegrations are entirelydifferent from ordinary chemical reactions andare independent of external conditions. Therate of disintegration does not change whetherat the temperature of white heat or of_liquidair. Moreover, the disintegration goes onat the same rate whether the radioactive elementis in a free or a combined form.

Note in the table below that some of thedisintegration products are stable for millionsof years while others disintegrate in a fewseconds.

Isotope

UraniumThoriumProtactinium

Uranium

ThoriumRadiumRadonPoloniumLeadBismuth

Polonium

LeadBismuthPoloniumLead

DISINTEGRATION

Symbol

U-238Th-234Pa-234

U-234

Th-230Ra-226Rn-222Po-218Pb-214Bi-214

Po-214

Pb-210Bi-210Po-210Ph-206

PRODUCTS OF THE U-238 SERIES

Half-Life period Particle emitted

4.5 x 109years alpha

24.10 days beta1.1175 minutes beta

2.48 x 10s years alpha

8.0 x 104years alpha

1622 years alpha3.825 days alpha3.05 minutes alpha26.8 minutes beta19.7 minutes beta

1.64 x 10-4 seconds alpha

19.4 years5.0 days138.4 daysStable form

457

betabetaalphanone

LEZ94


ACTIVITIES

ARTIFICIAL TRANSMUTATION OF ELEMENTS

The equations below are primirtlyyforthe information of teachers and represent trans-

. mutation by bombardment with high energy particles.

1. Bombardment la:protons.

9 1 6 4,4Be + 1H 4 31.2 + 2he

3L1 +

1H -+

2He +

2He

2. Bombardment bx: heavy hydrogen (51211121212)

209 . 2 210 1

83+ H 4

83Bi + H

1 1

3. Bombardment la:alpha particles

14 4 17 1

7N 4

2He 4

80 +

IH (Rutherford's work in 1919)

49Be +

2He 4 12^

6+on

4

45 4 48 '

21Sc + 2He 4 22T1 * 1H

4. Formation of plutonium from uranium

238 1 239 o92U +

on 4

92U +

oy

2239U

3992 93N12 * -le

239 239 o o

93-r 94P" -1e oY

Pupils frequently ask whether other metals maynot be transmuted into gold. This transmutationis possible but impractible from an economicpoint of view.

499

to-22

L.5.1ERENCE OUTLINE MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

D. Nature of Radiations

1. Particles

a. alphla particles +Alpha particles are helium nucleilath a mass of apprcximately4 a.m.u. and a positive charge of+2.

Each alpha particle contains twoprotons and two neutrons.

Alpha particles travel at a speedless than 1/10th the velocity oflight.

+Alpha particles lose their energyvery rapidly as a result of ionizationof the substances through whichthey pass.

Alpha particles darken photographicfilm and produce fluorescence incertain substances.

Due to their double positilmecharge, they easily ionize a gasand will activate a Geiger countertube if the window is very thin.-

+Alpha particles have slight pene-tration. A thin sheet of paper oran air space of several inches issufficient to absorb them.

*When anaalpha particle is emittedby an atom, a new atom is producedwith a mass reduction of 4 a.m.u.

*Alpha particles are charged andwill be deflected when passedthrough a magnetic field.

4

MATERIALS

geiger-muller tubealpha sourcemetric measurepaper

KEY WORDS

a.m.u.chargedeflectedfluorescencegeiger counterionizationionizemagnetic fieldmass reductionpenetrationvelocity

ACTIVITIES

The range of alpha particles is limitedin air. This range can be demonstrated inan empirical manner by using a thin mica windowGeiger-Muller tube and a point source of alphaparticles such as P0-210.

Alphaemitter

GM TMbe with thin mica window

F I I I I I I

.2 3 4 5

Take the background count for five minutes.Place the GM tube at a distance of lcm. fromthe alpha emitter and record the count fora 5-minute period. Correct for the backgroundcount. Repeat at the 2 cm., 3 cm.,...6 cm.-distances until the count equals the backgroundcount. If desired, plot the counts/minuteagainst distance. Repeat using a thin sheetof paper as an absorber inffrntt of the alphaemitter.

4 61

REFERENCE OUTLINE MAJOR UNDERSTENDINGS ANDFUNDAMENTAL CONCEPTS

B. beta particles +Natitrally occurring beta radiationconsists of high speed negativelycharged electrons.

+Since beta particles are charged,they ionize molecules of a gas.

The speed of beta particles rangefrom 25 to 99 Der cent of thevelocity of ligt/

+Because of their high velocity,beta particles are more penetratingthan the heavier /alpha particles.

Since beta particles are charged,they are deflected by a magneticfield.

*The emission of a beta particleproduces a new element with anatomic number increased by one andwith (practically) no change inmass.

Beta particles darken photographicfilm and produce fluorescence incertain substances.

Thin sheets of metal such asaluminum can be used to absorb'beta radiation.

Beta particles are deflected to amore marked extent in a magneticfield because of their smallermass.

When the gas contained in a Geiger-Muller tube is ionized by a chargedpatticle a pulsation is producedwhich can be ampflified and counted.

MATERIALS

G.M. tubealuminum sheetsring standbeta sourceringclamp

KEY WORDS

L-25

ACTIVITIES

THE RANGE AND ABSORPTION OF BETA RADIATION

Beta particles are usually stopped by passagethrough approximately 10 feet of air or byvarying thicknesses of metal sheet. A simpleexperiment to demonstrate the effectiveness ofan absorber for beta radiation is to set upa ring stand as illustrated in the figure witha source of beta radiation on the lower support,4 cm. from a GM tube with the window exposed.(P-32, I-131, uranyl nitrate or other radiationsources may be used.) Take a 5-minute countof beta radiations with no absorber in placeand record the average aactivity" in countsper minute.

Geicier-----Mita To o rn pl i Fiertuber II unit- ond counter

wi thwindow uopen

luminurn i-teets

C:7:3' Source oFbeta rodiction

Pinq qtand

Repeat using various types of shielding materials.

433

L1.25


MATERIALS

lead foilbeta sourcealnico magnet

KEY WORDs

L-27

ACTIVITIES

DEFLECTION OF BETA PARTICLES IN A MAGNETIC FIELD

Since beta particles are negatively claarged,

they are deflected when passing through a 12agnetic

field. The degree of deflection depends on thekinetic energy of the particles and.the strengthof the magnetic field.

Set up a linear arrangement as shown in Fig. 1

using slits in two sheets of lead foil to collimate

the beam of beta particles. A source of betaparticles may be P-32, 1-131, a radium button, or-

some uranium salt. Take a number of readings of

radioactive counts with a Geiger counter beforeusing magnets.

4,htrude

Window

r12-13crn?32 Or 01- rk. r

Fig. 1

&acid Loadsheet shoat-

Insert an Alnico magnet around the beam asshown in Fig. 2 so that the beam passes betweenthe poles of the magnet perpendicular to thedirection of the field. If more than one magnetis used (recommended), place the poles alternatelyNrS-N-S to increase the strength of the magnetic

field. Note the variation in beta counts withthe magnets in place and without.

The degree of deflection can be measuredby moving the GM tube up or down relative tothe slit in the lead shield. The directionof the deflection can be determined by the use

of the left-hand rule, if desired.

A.M. I.a rscnt.4L.11_-_, 1 Source of

Window i7---- radio!' inn Fig. 2

tAcd Mmr.o Leadshsekl magnet 3hisld

4 5

L-28

REFERENCE OUTLMNE MATERIMBERSTANDINGS ANDFUNDAMENTAL CONCEPTS

c. neutrons +Free neutrons are emitted duringnuclear reactions.

2. Gamma rays

+Released neutrons can traverseconsiderable distances throughair and penetrate appreciable thick-nesses of solid substances.

+Nerittrons can produce harmfuleffects on living organisms.

Neutron emission results fromsuch nuclear reactions as fission,and some fusion reactions.

The atoms of elements bombarded byneutrons become a source of radia-tion for doing useful work inscience, industry, medicine, andagriculture. Many of these acti-vated nuclei are used as processtracers.

+Gamma rays consist of very highfrequency electromagnetic wavessimilar to X-rays but of shorterwavelength.

Gamma rays have no mass or chargeand travel at the speed of light.

+Gamma rays have a high degree of

penetration. Materials such aslead or dense concrete can reducethe distance that they travel.

The high penetrating ability ofgamma rays makes them the mostuseful and the most dangerousof all nuclear radiations.

L-29


KEY WORDS

4q7

L-30

RFFERENCE OUTLINE MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

3:1Since gamma rays carry no charge,they are not deflected in a maonticfield.

It is generally not possible toabsorb gamma radiation copletely_However, if a sufficieof matter is placed b theradiation source and an individual,the exposure dose can be greatlyreduced.

+Gamma raysin air arlead or

hurrls of r.-et-itonped by thick

concrete.

MATERIALS

L-31

ACTIVITIES

PRODUCTION OF NEUTRONS

Free neutrons are produced whenelements are bombarded with alpha paz-ticles.Since neutrons have no charge, they are dif-ficult to detect. The production of freeneutrons occurs in high ener,Lor accelerators.Some examples are:

4 92He + Be

12C + n6 o

4. 21ri7e + I;M:g ,s5.

43lsAr + ,He

12 2 /.; 1.0 + .N + no 1'

An example c,f neutron formation through naturalradioactYie decay is:

KEY WORDS

electro-magnetic wavesexposure dosefree neutronsspeed of lighttraverse

87 8636Kr .)o

-.Kr + on

4cig

L-32


L-33


PENETRATING POWER OF NUCLEAR EMISSIONS

Heavy alpha particles will travel only aninch or so in air and are stopped by a thinhheet of paper. Beta particles travel as mucll

as 10 feet through air and may be stopped byseveral thicknesses of aluminum. Gamma rayspenetrate to considerable distances, eventhrough several inches of lead.

Copy the diagrams below on the chalkboardto give pupils a visual overview of the penetratIngpower of the types of ionizing radiation.

KEY WORDS

ALDriA-^''"

;

NEUTAONSTrowel noinorol.

lfler .n or, 000 or.tor or a,oco21

Po, Dv Ser.olo roar of

CAMmA

Or 'rt.,. Woo., ..,ree

7:71 L.eaC

irLL.11Gommo

AluminumI \

i5cra

i"." Czarr.:Cc: Iurce1

Aipho port.cksWY. PAGA by lin.or OW a-sheetof tISSu: pope

to ponickm GernrfiCI rays .

stopped by loft ctrfOluorcd factor ofof z:r OP-Shoot ICCO by 0.5mi of airof cli.anum cc ar 25fr. of corm

4 71

Paclioacfivemorcr,a I

REFERENCE OUTLINE

E. Detection ofRadioactivity

1. Photographicfilm

2. Spinthariscope

3. Electroscope

L-34

MAJOR UNDMESTANDINGS ANDFUNDAMENTAL CONCEPTS

Radioactivity may be detected byseveral devices.

+The chemicals in photographicemulsions react to nuàlear radia-tions.

+The degree of fogging or darkeningof film in a unit of time is aquantitative measure of the amowtof radiation received.

Photographic films are sensitiveto electromagnetic wave lengthsincluding those of visible lightand nuclear radiations.

An ionizing particle passingthrough a photographic emulsionleaves a chemical trail which is

visible upon development.

Some invisible radiations cause aphosphorescent material to lightup and thus indicate their presence.

This is nErelatively simple instru-ment used to detect alpha particles.

+Nuclear radiations cause air tobeomme charged (ionized). Chargedair particles discharge an electro-scope.

+The rate at which an electroscopedischarges is a measure of theintensity of radiation.

Air, ionized by radiations froma radioactive source, is attractedto a charged electroscope andneutralizes its charge.

4-.72

MATERIALS

KEY WORDS

Lt-3 5

ACT IVIT IES

473

L-36

REFERENCE OUTLINE MAJOR UNDERSTANIMNGS ANDFUNDAMENTAL CONCEPTS

One of the first instruments to beused in the study of radioactivitywas the gold-leaf electroscope.

The self-reading dositheter operateson the same principl& as theelectroscope. Dosimeters obtainedfrom civil defense are designed to

measure gamma radiation only.

MATERIALS

photograhizfilm

radioactivesource

tapedeveloper

KEY WORDS

developmentdosimeterelectroscopeemalsionfilmfoggingintensityneutralizesphosphorescentquantitativevisible

L-37

ACTIVITIES

DETECTING RADIATION WITH PHOTOGRAPHIC FILM

Students can duplicate Becquerel's discoveryby placing a radioactive source in close proximityto one or.7.several sheets of photographic filmwrapped in opaque paper.

Uranite, pitchblende, carnotite, and gummiteare minerals often found in school mlneralcollections which emanate enough radioactivityto satisfactorily darken photographic emulsions.A radioactive watch dial may also be used.

Tape the radiation source to the film andplace it and a control film packet in a cupboardor closet where it will not be disturbed.[Once the film packages have been preparted,darkness is not essentialp.

The exposure time will vary with the sensitivityof the film and the type and amount of radiationproduced by the sample. If a number of packetsare exposed to similar radioactive sources, eachfilm might be developed after a varied numberof days of contartt.

At the completion of the exposure time,processing shoald be completed in a contrast--type developer such as D-19 or X-ray filmdeveloper. (Any commonly used film developermay be used but the negative will show lesscontrast.) Prints may be made from the negativefollowing ordinary photographic procedures.

It is suggested that this demonstration isbest done as a student activity. The preparation,processing, and printing are familiar processesto many pupils.

Discuss the use of various detection devicesin prospecting for radioactive minerals.

L-38


MATERIALS

electroscoperubber rodradioactive 3source

L-39

ACTIVITIES

USING AN ELECTROSCOPE TO DETECT IONIZING RADIATIONE

A simple method to show the ionization of airby a radioactive source is through the use of asimple electroscope. Eit-rier a goldleaf oraluminum foil electroscope may be used to illustratethis phenomenon.

An electroscope consists of a metal rod withtwo small sheets of metal foil ached at oneend, and a container which ser to protectthe delicate leaves from air currents. Whenthe metal rod is charged, the leaves divergeand remain separated until tle charge is dissi-pated.

A qualitative test to show the ionizationeffect of a radiation source is to charge theelectroscope with a rubber rod. The leavesof the electroscope will dtverge indicatinga charge.

Place a source of radiation near (2-3cm.distance) the knob of the electroscope. Notethat the charge on the electroscope decreases.The rate at which the leaves are dischargedis proportional to the ionization of the airand proportional to the intensity of the radio-active source.

Choreedwelt rubber acedioective

Source of

rod bp Wolfe rodiotiort,lectricity

Leaves

rdives66i-i-owly co; loped

Indica-roleLeaves

char's' tees of eitiiirge

L-110

REFERENCJE:. OUTLINE MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

. Geiger-Mullertube(Geiger counter)

Radiations passing through a gascauses the gas to become charged(ionized). When the gas is suf-ficiently ionized a dischargeoccurs between two electrodes.

+The number of discharges in a giventime is a measure of the intensityof radiation.

47 F3

L-41

Ac'TIVITIES

THE PRINCIPAL OF OPERATION OF A GEIGER MULLERTUBE

Geiger-Muller counters are widely used

in radioactive detection and measurement. An

electric discharge takes place between twucharged bodies when a gas which surrounds thecharged body is ionized by a fast moving particle.

The essential part of this counter is theGeiger-Muller tube. See the illustration below

for its construction.

ttesewine:ow G se envelope

Parlicia

Meal Cylinder Cal-hodeGsz Igor-Mellor Tube

Anode

A tungsten wire is stretched inside a

metal cylinder. The wire is the positive electrode(anode), and the metal cylinder is the negatiVeelectrode (cathode). Both of these electrodesare insulated from each otner and may be sealed

in a glass envelope. The glass envelope is filled

wittli a dry gas usually argon or a mixture of argon

atidha polyatomic gas such as chlorine, bromine,

or an organic gasedmaFcompound.

479

L-142

REFERENCE OUTLINE MAJOR UNDERSTANLINGS ANDFUNDAMENTAL CONCEPTS

480

L-143


A voltage of 800 to 1,000 volts is placedacross the electrodes. Radiation from theradioactive substance enters the tube througha mica window. After entrance, the radiationcauses innization to take place. This is accomplishedby ripping off electrons from the atoms ef gas.Ions are produced having positive charges andothers having negative charges. The ions areattracted to the electrode of opposite chargeso fast that they in turn ionize other atoms

of gas. The formation of ions builds up theconductivity of the gas until a discherge occurs

in the tube. This discharge is a momentary pulse

of current passing between the electrodes. The

strength of the current depends upon the voltageapplied to the electrodes. This current canbe amplified through suitable electronic circuitsand be made to actuate a counting device orcan be heard as a click in a loud-speaker.Instruments of this kind can be used to measurebeta.

481

L-14 /4

REFERENCE._ OUTLINEE MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

MATERIALS

GM counterradiationsource(s)

KEY WORDS

L-45

ACTIVITIES

OPERATING A GEIGER COUNTER

Most schools can obtain a Geiger counterfor the detection of radioactivity. Contactthe Civil Defense office n your area for loanof an instrument. Science teachers should becomefamiliar with the operation of a Geiger counter.

A Geiger-Muller counter or "GM" counterconsists of a probe equipped with a beta shield,a high voltage cirouit, and a meter or earphoneto register the rate of Intensity of radiation.

The GM counter should be checked to seethat it is operating properly. First, turnthe selector switch to the X-100 or X-10 rangeand allow at least 30 seconds for warmup. Second,rotate the shlèld on the probe to the fullyopen position. Three, place the open areaof the-probe as close as possible to a knownsource of radiation. If nc clicks are heardor recorded on the meter, the batteries maybe dead. Check the batteries and replace ifnecessary.

If a Civil Defende instrument is beingused, a source of radioactivity will be foundon the side of the case. The meter at theX-10 range should read between 1.5 and 2.5mrihr. With the window open, the intt2umentreads both beta and gamma radiation. Gammaradiation is read with the window closed.

Most GM tubes will not detect alpha radiationsince the thickness of the window is sufficientto absorb this type of radiation.

A Geiger counter is a sensitive, scientificinstrument and cannot take physical abuse. Afteruse, be certain to TURN OFF CIRUTEITT otherwisethe batteries may corrode the case.

Hide a source of radioactivity. Have pupilslocate it by use of the detecting instrument.

L-46

REFERENCE OUTLINE MAJOR UNDERSTAND- NGL7 NDFUNDAMENTAL COir'17_,P.7.-3

Ti -147

MATERIALS ACTT_VITIES

KEY WORDS

Measure the counts/minute caused by a sourceat some distance (example, 10 centimeters) fromthe meter.: Do-oble, triple and quadruple thedistance and repeat the readings. What is theapproximate relationship between counts/minuteand distance? (The inverse square law is notstrictly applicable since the source is nota point.)

A Geiger counter adapted for Civil Defenseftse, the CD V-700, is illustrated below. Thisis a low range instrument that detects the presenceof beta particles and measures gamma dose rates.This instrument is designed for low level measure-ments (0-50 mr/hr) and has limited usefulness inareas of high contamination.

485

L-148

REF7RENCE OUTLINE MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

L-49


A detection instrument used for the majorsurvey of nuclear radiations is the CD V-715meter. This instrument measures gamma doserates only (no beta capability) and has 0-50Cr/hr. range.

L-50

REFERENCE OUTLINE MVOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

5. Cloudchamber

+Water vapor may condense and becomevisible along the trail of tonsproduced by an ionizing particle.

Dust free air that is'saturatedwith vapor becomes supersaturatedon sudden expansion in the cloudchamber. Excess vapor condenses

anL: uromand becomes visible along thetracks produced by the chargedparticle as it moves through thechamber.

The tracks of alpha particlesappear as straight lines of densefog droplets. Beta particlesproduce tracks much less dense.The tracks of gamma rays are veryfaint and scattered.

6. Scintillation Scintillations can activate acounters count±ng device.

Modern scintillation detectors usepheephors in combination with aphoto-multiplier tube.

Scintillation counters are superiorto Geiger-Muller counters forgeneral survey purposes especiallywhere gamma ray detection is con-cerned.

MATERIALSscrew-capfruit jar

black feltlight source(parallel beam)

ethyl alcoholdry icegamma source

KEY WORDS

6hamberexpansion

L-51

ACTIVITIES

OBSERVING TRACKS CF NUCLEAR RAT)IATION TNIN A CLOUD CHAMBER

The cloud chamber is the device that probablycomes closett to allowing the pupil to "see"

radiation. In a cloud 2hamber, liquid dropletscondense on the ions produced by a chargedparticle moving rapidly through the chamber.The tracks produced by gamma rays are faintand scattered. These tracks are due to thesecondary electrons ejected by the gamma rayson collision with the atoms of the gas in the

chamber.

A Wilson-type cloud chamber may be borrowedfrom the physics laboratory to show the ionizingeffects of nuclear radiations. If none isavailable, a simple cloud chamber can be made

--using a fruit jar, pieces of black felt, anddry ice.

The glass container from which this cloudchamber is made will not permit alpha and betaparticles to penetrate into the chamber. Gammarays, however, penetrate the chamber and ionizethe gas within the bottle producing trackswhich can be seen.

The materials needed are an ordinary screw-cap fruit jar, black felt, a source of lightcapable of providing a bright parallel beam,ethyl alcohol, a block of dry ice about 5 poundsor larger, and a gamma source.

To prcpar-a circle of felt to fit the inside of the cover,and another circle of felt to fit the bottomof the jar. The bottom piece of fIt is kept

in place by iron bgalpiggw4rpeo&rmiggielteodiswisg.ggeto provide a snug fit.

L-52


L-53


Pour just enough alcohol into the jar tosaturate both the top bottom pieces of felt.Tighten the cap and set the jar, cap down,on the cake of dry ice. Adjust the spot lightat an angle as shown in the sketch and lookdown into the side of the jar through the beamof light.

After approximately 5-10 minutes, whenconditions have stabilized, a supersaturatedlayer will form above the cold surface of thejar lid. When high energy particles from cosmicrays enter this zone, they form trails of ionson which condensation takes place, formingvisible cloud traces. The cloud tr,Icks shouldappear against the bldmak!:..backgroud at unequalintervals of time. When a gamma source isbrought near the jar, the size of the dropletswill increase, there will be more precipitation,and many tracks will be observed inside thejar.

It is possible to increase the displayby placing a weak source of alpha particlesin the chamber at the time it is assembled.This source should be supported just abovethe cooling surface.

KEY WORDS

fog dropletsGeiger-Muller counterionsphosphorphoto-multiplier tubescintillationsuper saturatedtl'ackvapor

-Block felt inside o$jar. Cut oversize to fitsnugly or held in placewith wireinsioe of jor saturatedwith alcohol vopor

oral lei beam- Block felt onside and bettomof screw top .

inside of jor

491

L-5/4


7. Bubblechamber

F. Rate of DecayHalf-Life

:.Ionizing particles can produce atrail of bubbles when they passthrough a superheated liquid.

If the pressure is reduced in aliquid already near its boilingpoint, bubbles wi21 form alongthe path of ionized particles.

Much can be learned about nuclearparticles by studying the bubblepaths.

.During a given period of time,a certain fraction cf a radioaciveisotope will spontaneouSly decom-pose. The time required for halfthe nuclei in a sample to decayiskknown as the half-life of theisotope.

Each radioactive isotope has adefinite half-life which is independentof the amount of material present.

Determination of half-life is astatistical process. Although itcan be determined fairly accuratelywhen :Ialf the number of radioactivenuclei will have decayed, it isimpossible to determine which oneswill decay during this time.

Some radioisotopes have very longhalf-lives, others decompose ina fraction of a second.

An isotope is considered stable ifits half-life is longer than tneage of the earth (4-6 billion years).There are no stable nuclei withatomic numbers higher than 83.

492

L-55


KEY WORDS

493

L-56


The half-lives of isoto', , rangefrom a fraction of a seond tobillions of years. As an examplethe half-life of polonium-214 is160 milliseconds whereas that ofuranium-238 is 4.5 billion years.

MATERIALS

KEY WORDS

boiling pointbubble chamberdecomposehalf-lifemillisecondpressurestatisticalsuperheated

L-57

ACTIVITIES

DOSIMETER DETECTION OF NUCLEAR RADIATIONS

The self-reading dosimeter operates upon the same principle asan electr:,scope. An electrical charge is pl:Aced on a quartz fiberand its parallel supporting rod causing the fiber to be repelled.These are both insulated from the outside container wall. Radiationentering the chamber, encasing the fiber and metal frame, causes theformation of ions which are collected on the quartz fiber or outsidewall. 'A reduction of the charge or: the quartz fiber is reflected inthe movement of the fiber. If a scale is inserted in the eyepieceand the charge on the fiber is adjusted to zero on the scale, thenthe movement of the fiber along the scale can br! calibrated toindicate the total accmulated ionizing radiation exposure or, asit is more commonly called, the total dose. Dosimeters that areobtained from and used in civil defense are designed to measuregamma radiation only.

CAP WITH WINDOW

SUPPORTING I NSULATOR

WIRE ELEM ENT

QUARTZ F .13 ER

ELECTRODE

ELECTROSCOPE---

LENSES

CASE

DOSAGE SCALE

EYEPIECE LENS--

SELF-READINIS POCKET DOSIMETER

Discuss half-life in relation to:

geologypaleontotogYarchaeologyastronomy, and other fields of science,

e.g.; effect on present information, dating;use in making new finds, etc.

L-58

REFERENCE OUTLINE MAJOR UNDE7.STANDINGS ANDFUNDAMENTAL CONCEI-TS

II. INauced Radioactivity

*l. Man-made elements

Bombardment of nuclei by accel-erated particles cause nuclei tobecome,unstable and may result inthe formation of isotopes or newelements.

Unstable nuclei decay into othernuclei with the emission of radio-active particles and usually witha release of energy.

Transmutations involve high energyparticles such as protons, deuterors,and alpha particles.

Many radioactive isotopes producedartificially serve useful purposesas "tracers" in industry and medicine,

Nuclear reactions involve energiesmuch greater than ordinary chemicalreactions. The energy changes maybe a mLllion or more times larger.

*Elements with atomic numbersgreater than 92 have been made bybombardment of atoms by neutrons.

4c3B

MATERIALS

KEY WORDS

L-59

ACTIVI1IES

THE TRANSURANIUM ELEMENTS

The capture of free neutrons by uranium during neutron bom-bardment has produced elements of atomic number.greater than 92.

accelerationartificiallyatomic pilesbetatroncyclotronelectronenergytracersvan de Graff generator

Most stable isotope At.No. Estimated half-life

Neptunium-237

Plutonium-244Americium-243

Curium-247

Berkelium-247Ca1ifornium-251Einsteinium-254Fermium-255Mende1evium-256NobiliumLawrencium

93 2.20 x 106years

94 3.73 x 105years

95 7950 years

96 4 x 107years

97 7 x 103years

95 660 years99 280 days100 22 hours101 0.5 hours102 *Existence of stable103 isotopes is doubtful.

1. Make a van de Graff generator

2. Discuns--the historical developmentinduced radioactivity.

4 97

L-60'

REFERENCE OUTLINE MAJOR UNDERSTANDINGINANANDFUNDAMENTAL C'.DNCEFTS

2. Accelerators

III. Nuclear Fission

Accelerators or "atom smashers"are devices used to increase thevelocity of atomic particles.

Scienttlittsuse accelerators to

explore the forces that hold to-gether the nucleons, the natureof the particles inside the nucleus,and tne processes that go on among

nuclear particles.

The pyttaiple behind each acceleratoror "atom smasher" is to provide particleswith sufficient kinetic energy sothat they might penetrate the nucleusof the element being bombarded.

Pa-fticles and the devices withwhich they are generally associatedinclude respectively; electrons(betatron); protons (proton synchro-ton); alpha particles (cyclotpon);deuterium (synchrocyclotron);neutrons (nuclear reactor).

In the fission process the nucleusof a heavy element is caused tosplit into two or more partsreleasing large quatities of energy.

Fission of heavy elements isstarted when a neutron is absorbedby the nucleus.

In addition to the release ofenergy, the fission process re-leases products such as betaparticles, neutrons, and gammarays.

L-61


KEY WORDS

atom smasherfissionheavy elementkinetic energynucleonsproton synchrotronsynchrocyclotron

499

L-62


A, Chain Reactions

B. UncontrolledReactions

A few pounds of fissionable materialcan liberate as much energy as theexplosion of thousands (or milli,:ns)

of tons of T.N.T. This is theenergy source for the nuclearbomb (atomic bomb).

The equation for the fissitn ofuranium-235 is:

235 1 141U4

92 0 56

92Ba+ Kr+3 n4.energy

36 0

The mass of the products is lessthan the mass of the fissionablenuclei and the neutrons whichstrike them. The mass which hasapparently been lost has beenconverted into energy in accordancewith the Einstein equation.

2

E=mc where c is the velocity of

light.

When the nucleus of some heavyelements is hit by a slow movingneutron, the nucleus splits andalso yields one or more neutrons.If conditions are right, theseneutrons may cause other nucleito fission. This reaction is self-sustaining and is called a chainreaction.

An uncontrolled reaction continuesuntil there are no more availableneutrons striking fissionablenuclei.

MATERIALS

waste paper basketmousd trapspaper

KEY WORDS

atomic bombchain reaotionE=mc2Einsteinexplosionfissionableliberateselfsustaininguncontrolled reaction

L-63

ACTIVITIES

The principle of U-235 chain reaction can be demonstrated

very dramatically by means of several mousetraps and a large waste-basket, Each mousetrap will represent an atom of U-235. When themousetrap is set, it has energy just as an atom of U-235 has.

Paper wadsto representneutrons

Woste-basket

Poperwads

Make a dozen pPper wads each about one inch in diameter. These

will represent neutrons. Set six mousetraps and place them very care-

fully in the bottom of the wastebasket. Opposite the trigger of each,

'place two paper wads as shown in the diagram.With everything in readiness, drop a paper wad neutron on the trig-

ger of one of the mousetraps. If a direct hit is not scored on the first

try, call attention to the fact that this often happens and that many

neutrons are left over in a real chain reaction. As soon as a direct hit

is scored, the paper neutrons will be set in motion and all the mouse-

trap atoms will give up their energy accompanied by considerable clatter

within the wastebasket.

1. Make various devices to show chain reaction.

2. Discuss various ramifications of E=mc2 ,

especially its abstractions.

511)

L-64


C. ControlledReactions

IV. Nuclear Fusion

Fission reactions are controlled byregulating the speed of neutronsor the number available for furtherfission reactions.

Fission reactions are controlled ina nuclear reactor (atomic pile).

Neutrons are slowed down by modera-tors such as graphite. Controlrods made of such materials asboron steel will absorb neutrons.

Nuclear reactors provide a controlledsource of heat energy whlth canbe converted to electrical energy.

Many useful rauioactive elementsare produced in the nuclear reactor.These radioisotopes are usedeffectively in medicine and inindustry.

A single pound of U-235 yields about3 million times more energy thanncan be yielded by burning a poundof coal.

In nuclear fusion, a pair of lightnuclei unite (or flide4 together toform a nucleus of a heavier atom.In the process of fusion, mass isconverted into energy.

The principal of the fusion processis derived from the theory ofrelativity of Albert Einstein(1877-1955).

L-65


KEY WORDS

L-66

REFERENCE.OUTLINE MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

The mass-energy equation E=mc2

,

indicates the tremendous energyevolved when mass is converted toenergy.

An example of a fusion reactioninvolves two atoms of deuterium(hydrogen-2) which produce heliumand energy:

22241-1-0.He+energy.

1 1 2

51)4

MATERIALS

Mouse trapscord/stringmarbleradiometercardboard

KEY WORDS

controlleddeuteriumelectrical energyfossil fuelsfusefusionmassenergymoderatornuclear reactorradioisotopes

reaction

equation

L4$7

ACTIVITIES

The multiplying nature of the 1:1-235 chain reaction can be fur-ther.clarified by arranging set mousetraps as shown in the diagram.When a small object representing a neutron is dropped on the first trap,it springs and starts a chain reaction which passes on to the rest ofthe traps.

Marble representsID neutron

THE NUCLEAR REACTOR IS AN Ai-OA-IC-FURNACE

REACTORHEAT EXCHI NGER

STEAM TO7U1I1W411

____--------"jREACTORURANIUM PIM =,--"L'' ' PUMP

COOLANTPAMS

40, WATiaINIAER

Place a radiometer in the sunlight nearthe window and develop the idearthat it runsby atomic energy. Shield it from the directsolar radiations with a piece of cardboardand notice that it immediately slows down.

505

L-68

1:EwERENCE OUTLINE MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

High temperature is required toactivate the fusion process.FusiOnnl'eactions are called ther-monuclear reactions..

The thermonuclear or H-bomb isactivated by the heat of a fissionreaction.

V. Uses of Radioactive Radioisotopes are used in a wide

Isotopes variety cbf quality control techniques.

A. Chemlstry

B. Biology

Tagged atoms allow the chemist tofollow chemical reactions evenwhere no observable chemicalcharges take place.

The chemist uses radioisotopes toidentify the purity of chemicals,to develop separation schemes, andto carry out kinetic studies.

A great deal of inorganic chemistryinvolves separating ions or com-pounds.

In organic chemistry, the taggingof elements permits an analysisof the molecular structure andthe detection of reaction intermediates.

Biologists use radioisotopes as anaid in tracing chemical interacticnsin organisms.

Carbon-14 has been useful instudying the mechanisms of photo-synthesis.

5f)i3

L-69


tinker-toy set

KEY WORDS

One way in which the fusion of hydrogen atoms to formhelium atoms may occur can be illustrated by nazans of wooden con-struction sets. Start with two hydrogen atoms, each consisting of an

electron and a proton. Now add a neutron to each atom to form twoatoms of deuterium. Bring the two deuterium atoms together and con-nect them to form a helium atom. This, of course, is an oversimplifica.tion of the process and does not explain where the energy comes from.

Some inkling of this can be gained from the following facts.Two deuterium atoms weigh more than a helium atom. Since a

proton weighs 1.00758 and a neutron weighs 1.00893, two protons andtwo neutrons should weigh 4.03302. The observed mass of the heliumnucleus is only 4.0028. The fuwon of two deuterium atoms thus resultsin a loss of weight equal to .03022. This loss of weight, resulting fromthe fusion of the two atoms, can be accounted for by assuming that this"lost" weight is converted into energy.

Elech-ons

Protons

Neuftonsadded

2 hydrogen atoms+ 2 neutrons.; 2 deuterium atoms fused2 cieuterium otoms together =I helium atom -I-

ejagrsy

carbohydrate formationcarbon-l!1chemical interactionschromatographic techniquediagnosisdilutionsdistillationsfiltrationsimpuritykinetic studiesphotosynthesisprecipitationquality controlreaction intermediatesseparation schemessyhthe1istagged atomtechniquetherapeuticthermonuclear

507

L-70


D. Agriculture

The utilization of radioisotopesin medic:al reaearch and treatmenthas produced a new era of medicalprc,gress.

Radioisotopes used as tracers andas therapeutic agents in medicineinclude:S-35 - to measure the volume

of extracellular fluid

Cr-51 - to label red blood cells

I-131i- to treat tumors in thethyrOith7glaEld:addtibomeasure the rate ofmetabcIlism

Co-60 - to treat cancer andtumors

Au-198- to control excessivefluid formation inabdominal cancer

Research utilizing radioisotopeshas increased the efficiency ofagricultural production. Suchresearch includes:

BybEnixing a radioisotope P-32into phosphate fertilizers, theactualluptake of fertilizer materialby the plant can be followed.

MATERIALS

plantsP-32waterbottles/flasks

KEY WORDS

cancerexcretionsextracellularfertilizerinjectedirrigationmulchesnutrientphysiolotyradioiodinethyroid glandthyroxinetumor

L-71

ACTIVITIES

Tweet.

PLANT UPTAKE OF P-32

Young tomato plants easily absorb

P-32 from solution.The P-32 uptake can

be detected with a GM counter or the

leaves may be placed in contact with

X-ray film producingradioautographs of

the leaves when the film is developed.

Control plants should be used and

several plants might be placed in lesser

dilutions of the P-32 solution so that

charts of varyingabsorptions can be

made.

Top watercontainingI alic P.32

Tomatoplant-

Reqi, lartapwater

Contra!plant'

L-72

RENCE OUTLINE MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

E. Archeology

In North Carolina, a new varietyof peanut has been developedthrough radiation mutation. It

has a much stronger hull and canbe handled with less breakage thanthe original type.

A variety of peach tree has beendeveloped which bears fruit twoweeks later than normal, thuslengtnenkng the processing andmarketing period.

Control of insect pests bysterilization of male insects.

Studying the action of fungicides,insecticides, and weed killers.

The eradication of the screwwormfly f-om the entire SoutheasternUnited States was accomplished byexpssing flies' larvae to a doseof radiation sufficient to causesexual sterility.

Preservation of foods.

The age of archeological dis-coveries can be estimated throughan analysis of the abundance ofC-14 in a relic. This techniqueis known as carbon dating.

The Dead Sea Scrolls, charcoalaround pre-historic campsites, rushmatting from an old Nevada cave,rope sandals in an Oregon cave, andwood from an Egyptian funeral boatare examples of items dated by theC-14 technique.

L-73


KEY WORDS

archaeologydecayfungicideinsecticidelarvaemarketingmutationpreservationrelicscrewwormspecimansterilization

5:eL 1

L-7/4

H'FFERENCE OUTLINE MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

F. Industry Radioisotopes permit testingwithout mutilating the product.

Radioisotopes are used in manyindustrial processes for Qualitycontrol, product testing, anddetection of wear characteristics.

There are many applications ofradioisotopes in industry. Someof these include use in:

thickness gaugeslevel indicatorscontrol of coating thicknessmeasuring viscosity in opaque

liquidswear in piston ringsabrasion of rubbereffectiveness of soapsdetermination of separation

efficienciesdetection of leaks in buried

pipesdetection of flaws in castingsand many more

MATERIALS

KEY WORDS

applicationproduct testingtechnologicalviscositywear

L-75

ACTIVITIES

INDUSTRIAL USES OF RADIOISOTOPES

Have pupils explore reports in industrial journals, magazines,

newspapers, et al, to find uses of radioactive isotopes in industry.

A number of select uses include:

Process Control:Thickness gaugesLevel indicatorsSpecific gravity measuresControl of coating thickness

Product Testing:Wear of distributor points in auto engines

Wear of piston ringsAbrasion of rubberWear of shoesEffectiveness of soa-2s and detergents

Wear of bearingsEffectiveness of fertilizersEffectiveness of dry cleaners

Service to Industry and to the Public:

Detect leaks in buried pipes

Locate manhole covers under snow

Trace pollution and sewageDetect scrapers in pipe lines

Indicate replacement of brake linings

RADIOISOTOPES IN QUALITY CONTROL

The sketch below shows how radioisotopes are used to control

thickness of an industrial process.

For example, in an aluminum rolling mill, the thickness gauge

using a radioisotope cancontinually measure the thickness of

aluminum over a range of 0.0002" to 0.075". The thickness gauge

automatically adjusts the rollers so that the aluminum sheet is of

uniform thickness.

In operation, a source of beta radiation is placed beneath the

thin moving strip and a radiation detector unit is mounted above the

strip. The thin sheeting will absorb part of the radiation; the

amount absorbed being roughly proportional to the thickness of the

aluminum sheet. Thus the radiation detector can be calibrated to

read in terms of sheet thickness.

Radioisotope thickness gauges are used to control many dif-

ferent types of sheet material: metals, paper, plastics, rubber,

textiles...

5 3

L-76

REFERENCE OUTLIEE MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

L.:17


KEY WORDS

RADIOISOTOPES MEASURE LIQUID LEVELS

Cans of liquids of all types - beverages, detergents, etc. nay

have the level of their liquid measured by a sensitive radioisotope

level gauge during the filling operation so that improperly-filled

cans may be detected and corrected.

Similarly, the level of liquids in large storage tanks can be

measured and adjusted by the use of radioisotope level gauges.

RADIOACTINE COBALT Co60FOR INDICATING LIQUID HEIGHT

SHIELDED Co 60SOUACE

HEIGHT OF COUNTER ANDSOURCE ADJUSTAILI ON TRACT.

GEIGER

OUNTIR

COUNTING RATEMETER

ADVAN FACES:I - C.-GE NOT AFFECTEO BY CORROSION ANO TEMPERATURE2- CAN BE OPERATEO BY NON-TECHNICAL PERSONNEL

3 - ADAPTABLE TO AUTOMATIC RECORDING AND CONTROL OF UOUID LEVEL

With tracers, it is possible to keep an extremely accurate con-

trol over the proportion of ingredients in fuel mixtures. In .

addition, radioactive atoms can be used to signal the arrival of

various liquids flowing throrah pipe linos.

RADIOACTIVE ATOMS MEASURE WEAR

The wear characteristics of many materials can be determined

long before the amount of wear is visible to the eye.

This idea is illustrated by tests made on the wearability of

shoe leather. A radioisotope wasincorporated into the leather sole

of a shoe placed on a special machine which simulated a walking

action. As minute amounts of the leather wor,o off, they carried tiny

particles of the radioisotope with them. A radiation detector

measured the radiation. Thus it was possible to measure the rate of

wear in a very short period of time.

Rubber manufacturers, similarly,measure the rate of wear of

automobile tires., Wear tests have also been made on floor waxes and

polishes.

Oil firris use radioactive piston rings to improve the qv,ality

of their lubricating oils. As the friction between the piston ring

and the cylinder wall increases,radioactive particles from the

piston ring enter the oil and are measured by a detector. The

radioisotope technique is so sensitive that accurate wear rates can

be detmnsined even though the amount worn is too small to be

weighed or seen. .

5 1 5

REFERENCE OUTLINE

VI. Radiation Safety

A. Effects of Radiation

1. Biologicaleffects

L-78


141-welear radiations are harmful toViving organisms.

Protection against radioactiveparticles and radiations is cssen-tial to ron's existence.

:Nuclear radiations cannot be seen,heard, smelled, tasted,or felt.Instruments must be used to detectand measure radiation.

Neutrons and gamma radiation aremore penetrating than alpha andbeta particles and sre more dan-gerous (all other factors beingthe same).

-The effects of radiation varyamong individuals.

Most people show symptoms ofradiation sickness if they receivean acute dose of 100 to 550 ormore roentgens in a four day periodor less.

he effects of nuclear radiation onhumans depend on the amountabsorbed, the rate of absorption,and the region and extent of thebody exposed.

Primary symptoms of radiation sick-ness include nausea, vomiting, ordiarrhea. These symptume nayappear during the first or secondday after ikposure.

L-79


KEY WORDS

lassitudenausearadiationroentgens

sickness

51 7

L-80


a. exposure to AlAlpha particles present no hazardexternal sources beyond a few inches from an

external source.

b. exposure tointernal sources

c. effects ofdelayed fallout

2. Effects onagriculture

Beta radiation presents no hazardover a few yeaddsfrom an externalsource.

The general biological effects ofnuclear radiations from an internalsource are the same as from anexternal source. However, a verysmall amount of radioactivtl materialpresent in the body can produceconsiderable injury.

.Iith an .n a 1 r - , t h e

The long half-lives of somefission products and theirdecay products make themdangerous for a long periodof time.

The human body has no instinctivedefense against radiation. Severedamage can result from exposure toradiation without the subject'sbeing aware of the extent ofradiation received.

There may be a delay of weeks,months, or years before the totaleffedts of exposure to radiationbecome apparent.

Since the effects of exposure toradiation are cumulative, the per-miss_Lole exposures to radiationdepend upon the age of the indi-vidual.

Crops that have not been harvestedcan absorb harmful radleact4Lvematerial and incorporate them intotheir tissues.

L-81


KEY WORDS

calcifyingcataractconcentrationconvalescencegeneticinhalingingestingleukemiamarrowprostrationsuccumbs

519

L--82

'EFERENCE OUTLINE MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

Croos that havc., not been harvestedwill be subject to contaminationon the outoide. If fallout paticlesare removed, the food'may be consideredessentially "uncontaminated".

L-83


DETECTING NUCLEAR RADIATIONS

Radiation from fallout cannot be seen, heard, smelled, tasted,

or felt; instruments must be relied upon to detect and measure

radiation.

715-64°

mw/hr0.2 0.3

toossumilmusi ito-.100 200

CD V-700

Several types of instruments are used to detect radiations. The

dosimeter (or a photographic badge) measure accumulated exposure.Survey instruments measure current radiation intansity. Samples of

these instruments are available from Civil Defense. Pupils should

become familiar with the operation of these instruments._

KEY WORDS

affinityanemiacontaminationharvestedinstinctivelethalmetabolismtolerance

L-84


3. Effects onindustry

Food and water which. are exposedto radiation, but not contaminated,are not harmful and are fit forhuman consumption.

Crops from soils rich in Sr-90should be considered unsafe. Otherisotopes have either short half-lives or low uptake by plantsmaking decontamination unnecesfsar.

Foods in the process of preparationgenerally have no cover protectionand may be rendered unsafe byradioactive isotopes.

Photographic materials are sensi-tive to radioactive isotGpes.Although precautions are taken tominimize the effects of naturalradiations, any general increasein radiation, particularly gammaradiation, will ruin the productseven if these have already beenpackaged.

In general, unless wholesaledestruction occurs, most industrialplants are not seriously affectedby radioactive fallout unless thearea is rendered a radiation hazardfor the workers.

5))2

L-85


KEY WORDS

consumptiondecontaminationfalloutminimizenatural radiationsreconnaisance

FOOD FROM LAND CONTAMINATED BY FALLOUT

DANGER FROM STRONTIUM-90

Crops grown on land contaminated with fall-out take up from the soil some of the long half-life radioactive materials, along with otherminerals needed for their growth. -ne most haz-ardous of these is radioactive strontium(strontium-90). Chemically, it is similar tocalcium which is needed by plants, animals andman. The roots of plants cannot differentiatebetween the two, and take up some strontium 90along with the calcium. Some plants build muchhigher concentrations of calcium, and strontium,into thein tissues than others. They also storemore of it in some parts of the plant than inothers. Small amounts of strontium-90 can betaker up from contaminated soil by successivecrops for years. If man continues to eat plantfood containing considerable amounts ofstrontium-90, enough of it can be concentratedin his bones to materially increase the chanceof his developing delayed disease such as bonecancer or leukemia. That is a hazard that shouldbe reduced to the lowest possible level.

MILK FROM CONTAMINATED ANIMALS

Milk produced by cows grazing on contaminatedgrass is likely to contain sufficient amounts ofradioactive substances to be hazardous for con-sumption.

MEAT FROM CONTAMINATED ANIMALS

Some radioactive material is absorbed by thebody and concentrated in bones or glands. Theinternal organs of exposed animals such as theintestine, liver, and spleen should be discarded.The muscle meat may not contain high concentrationsof radioactive substances likely to be dangerousto humans.

1,-436

Nuclear exr:losions of any type canbe disastrous and may cause seriousdamage to life and property.

It is the personal responsibilityof each individual to be aware ofthe precaations to take when anuclear de:!ice explodes.

Nuclear explosions are accompaniedby four destructive phenomena:

blastheatinitial radiationfallout

Blast, heat, and radiation a7ealmost instantaneous at the momentof detonation, but fallout pro-duces its effects later, longer,and over a wider area.

Most of the immediate damage ofthe explosion of a nuclear deviceis due to the effect of the blastwave and the energy released inthe form of heat.

To gain personal protection fromthe thermal radiation, it is neces-sary to get out of the direct pathof the rays from the fireball.

The thermal radiation travels atthe speed of light; the blast wavetravels at the speed of sound.

4

MATERIALS

KEY WORDS

blastdetonationfireballnuclear devicephenomenaprecautionsrenderedthermal

L-87

ACTIVITIES

BLAST AND THERMAL DAMAGE FROM NUCLEAR EXPLOSIONS

A 5-MT burst at ground level would leave a

crater one-half mile wide. The blast, heat, and

fire caused by the explosion would cause wide-

spread destruction, but radioactive fallout would

be a much greater hazard. It could spread overthousands of square miles and sicken or kill un-

protected people many miles from the point of

detonation.

RANGE OF DAMAGE FROM A S-MT BURST

Radii Area(sq. miles)

0-3 mi. 28.3

, 3-6 mi. 84.7

6-9 mi. 113.0

9-12 mi.

Beyond 12 mi.

Effect

All buildings almost completely des-troyed by blast. Total death fromblast and heat within this range.

Most buildings damaged beyond repair.Nearly 100% deaths within this area.

Moderately damagee buildings thatmust be vacated during repairs.Danger of 1st degree burns, blast,and early fallout.

226.4 Partially damaged buildings. Dangerfrom both early and late fallout.Danger of 2nd degree burns.

Danger of both early and late falloutif protection is not provided.

REFERENCE OUTLINE

1. Air burst

L-88


The air burst explosion occurs inthe air above land and water and nopart of the fireball strikes thesurface

MATERIALS

KEY WORDS

air burstblast wavedebrisdispersedfission productsmaximum brilliancemegatonmicronprecipitation

L-89

ACTIVITIES

COMPARATIVE SIZES OF NUCLEAR EXPLOSIONS

Aftil'udeVeen

;50,000 1.--

100,000

50000

SURFACEA-bomb H-oomb Thunderstorm

Comprative size of A-bomb mushroom, H-bomb mushroom, and Thunderskem cloud

,/ NUCLEAR EXPLOSIONS -- AIR BURST

An airburst occurs at sufficient height above the surface of

-'the earth to prevent the fireball from coming in contact with the

surface. The quantitative effects of an airburst will depend upon

the actual height of the explosion as well as the energy yield.

Air Burst

5 7

REFERENCE OUTLINE

?. Surface burst

L-90

MAJOR UNrEi'iSTANDINGS AND.FUNDAMENTAL CONCEPTS

The surface burst explsion occurson the surface (or when a parttbe fireball crikes the surfcice).

A turface burst causes much morradioactive fallout than an u:ir

burst.

Radioactive fallout from a crfacoburst may be carried me.71:51 byprevailing winds.

3. Subsurface bursts Subsurface bursts occur benhthe surface= c,f :1%;Id or wav-?r,

L-91


NUCLEAR EXPLOSIONS -- SURFACE BURST

When a nuclear weapon is exploded close to the ground, thou-sands of tons of earth, rock and debris will be melted and vaporized.rhis gaseous material mingles with the fission products in therapidly rising fireball. The majority of this material serves as acarrier for the.fine particles of radioactive material that resultfrom the cooling of these gases. These particles fall back to earthwithin a short period of time as radioaczive fallout. Very fine andless dense debris may remain aloft for longer periods of time,carried and dispersed by winds, and thus present a hazard forgreater distances and for a longer period of time.

A surface burst causes much more radioactive fallout than an air burst

Blast wave Radioachve cloud(Residual

radiation),Thermal

radiation

Surface 5ur3h

KEY WORDS

compression wavedisturbancesincorporatedprevailingstratospheresubsidesurface bursttransmittedtropospherevaporized

Initial nuclear-2.;sation

REFERENCE OUTLINE

C. PhysiologicalEffects of Radia-tion

L-92

MAJOR UNDERSTANDINGS AYDFUNDAMENTAL CONCEPTS

Exposure to radiations can pro(2uceharmful body effects. Nuclearradiation causes injury by damagingliving tilsue and cells.

When large amounts of radiationare absorbed by the body in shortperiods of time, sickness anddeath may result.

530

L-93MATERIALS ACTIVITIES

PHYSIOLOGICAL EFFECTS OF RADIATION

The harmful effects of radiation appear to result from the

ionization produced in cells composed of living tissue. As a resultof this ionization some constituents which are essential to the

normal functioning of the cells are damaged or destroyed, In other

cases, by-products formed from ionization reactions may act as cell

poisons. Among the observed actions of nuclear radiation in cells

are: breaking of chromosomes, swelling of nuclei and of the entirecell, destruction of cells, increase in viscosity of cell fluid and

increased permeability of the cell membrane. The process of celldivision (mitosis) is delayed by exposure to radiation. In many

cases cells are unable to undergo mitosis, thereby inhibiting norm*

cell raplacement.

Possible E Effects of Acute Gamma Radiation Dosages overWho_ Body During Exposure of One Day or Less

Acute Dosein Possible

Roentgens Effects

KEY WORDS

criticaldemarcationresidualsubsurface

0- 25r No obvious injury.25- 50r Possible blood changes but no

serious injury.

50--100r Blood-cell changes, some injury,no disability.

100-200r Injury, possible disability,generally not fatal

200-400r Injury and disability certain,death possible.

400-450r 'Median lethal dose fatal to50% within 2 to 12 weeks.

600-700r Lethal dose fatal to 95% ormore within 2 weeks.

Somewhat larger doses may be accepted, with aneqvivalent likelihood of injury if exposure is

protracte ,. over several days or weeks.

REFERENCE OUTLINE

D. Protection AgainstEffects of NuclearExplosions

L-914


The danger from radiation 0.epetsupon the degree of exs,:Dosure (t.eintensity and time of exposure).

Protection from expo-sure toexternal radiation denends upon:

time since the blasdistance from the 11,1:tamount of shielding

1. Effect of The amount of radiati(Jn fr,..m atime source decreases with time.

It must be emphasized that tnenuclear radiation in fallout caot,be destroyed. Neither hoili-T4 nc:27ourning, treatment with chemi:_yaIs,nor any other action will destroyor neutralize radioactivity.Because of radioactive decay, fall-out will become less harmful withthe passage of time, but there isno known way to speed up the decayprocess. Fallout cannot be madeharmless quickly. However, fall-out can be removed from many con-taminated surfaces.

MATERIALS

KEY WORDS

approximationfactorprimary decaysecondary decayc:_nren-foldshieldingtime period

L-95

ACTIVITIES

TIME--A FACTOR IN NUCLEAR DECAY

A close approximation of decay of fallout radiation can be

obtained by assuming that the dose rate will decrease by a factor of

10 for every 7-fold increase in time. This is an operatioaal

assumption for the protection of individuals during fallout. Many

isotopes have extremely short half-lives whereas others are radio-

active for years.

Time - Decay

TIME (hr.) DECAY

1

7

7X7 =49 (2 days)

7X7X7 =343 (2 vas)

1/100

1/1.000

RADIATIONINTENSITY

1.000 vhr

too vhr

10 Or

r/br

remay-=7 :10 Rule

HMI LIVES OF SOME FISSION PRODUCTS

About 200 different isotopes of nearly 40 elements have been

identified among fission products created by nuclear explosions. The

radioactivity of each isotope diminishes or "decays" at a specific

rate, different for each isotope. Usually the rate of decay is

expressed in terms of the "half-life" of th, isotope. Some isotopes

lotn half their radioactivity within seconds after the explosion.

Others take days or months or years to lose half their radio-

activity. For example, iodine 131 has a half-life of 8 days. Thus,

iodine 131 has decayed to half its original activity in 8 days,

half the remainder is gone in another 8 days, and so on. After 64

days, only 1 percent of the radioactivity will remain. Strontium-90

has a half-life of 28 years and 1 percent of the radioactivity nf

strontium will still remain after 1E0 years.

are:

1;alf-Lives of some rad:koactive isotopes significant in fallout

IsotopeSilicon 31 2.62 hours

Sodium 24 15.06 hours

Iodine 131 8.14 days

Phosphorous 32 14.3 days

Cobalt 60 5.27 years

Strontium 90 28 years

Cesium 137 33 years

Carbon 14 5568 years

The total radiation hazard of newly formed, or fresh fallout,

decreases rapidly at first because it contains many radioisotopes

with short half-lives. The radiation hazard decreases more slowly

after the shorter half-lifeelements have lost most of their radio-

activity.

5 3 a

L-96


2. Effect ofdistance

FUNDAMENTAL CONCEPT-

As the distance from the point ofimpact inereases, the ?robabilityof survival Increases and thedamage to bui7ding3 decrease6.

The intensity of radiation variesindirectly as the squere of thedistance from the (point) soueeeof radfLation.

Winds may carry radioaoeive mate-rial away from the point of theexplosion.

It is important to point out thatthe intensity of radiationdecreases as the distance from thesource Increases. If a nuclearexplosion occurred in Buffalo andif all of the radioactive productsremained at Buffaio, the onlydanger from radiation would beclose to Buffalo. However, whenwinds carry radioactive materialwhich later falls on the surfaceelsewhere, the location of thesource of radiation has moved.

MATERIALS

KEY WOR-

approximationindirectlyinverse square lawpoiht sourceprobability

L--97

ACTIVITTES

DISTANCE OFFERS PROTECTION AGAINST NUCLEAR RADIATIONS

A 5-megaton burst atground level would leave a crater about

one-half mile wide in the area of the explosion; it would destroy

nearly everything withinthe radius of a mile from ground zero.

The destruction at 5 miles away would be less severe, but fire

and fallout could be significant hazards.

Ten miles away, most buildings would remain intact but fires

would be started indirectly by the blast wave which follows a burst.

Somewhat further away, buildings would remain standing. The 7-

most acute danger of these greater distances downwind from the

explosion would be from early fallout.

Effect of Dishance on PadiatIon 10-eristrs;

POS LAST EFFEC

TOTAL DESTRUCTION

GROUNDZERO

OF A 5- BLAST

SEVERE MODERATE LIGHT

DAMAGE DAMAGE DAMAGE

FIRE881:..83 MILES RADIUS

Ci,ATER21 MILES RADIUS

5 5

3 MILES

I If

5 MILES 7 MILES 9 MILES

-rowdble, range of damateaurface buret._

REFERENCE OUTLINE

L-98


r.i G

L - 9 9


'DISPERSION OF FALLOUT IN NEW YORK STATE

Winds play an important part in the dispersion of fallout.

Winds in the northern part of the United States are prevailing

westerlies for the greatest portion of time. Therefore, winds

are a factor in the dispersion of fallout throughout New York

State. Note also the effect of time and distance on fallout.

TYPICAL FALLOUT SPREAD

KEY WORDS

L-100

EFERENCE OUTLINE MAJOR UNDERSTANDINGS ANDFUNDAMENTAL CONCEPTS

3. Effect of Protection from local fallout is

shielding accomplished by shielding.

E. Shelters

In general, protection increaseswith an increase in the thicknessand/or density of the shieldingmaterial.

A shelter places a mass of materialbetween individuals and the sourceof radiation.

Many parts of existing buildingsprovide good protection againstfallout radiation and some measureof protection against blast andheat. Basements and central areasof high rise buildings offersatisfactory fallout protection.

Every citizen has a responsibilityin case of a nuclear attack--firstand foremost, the responsibilityfor his own protection. Everyindividual must become capable ofcaring for himself in an emergencyand be ready to contribute to theorganized community survival effort.Each family must train and nrepareto meet its own emergency problems.Each family must also prepare it-self to assist others in need.

iTERIALS

(EY WORDS

3ommunitylocal falloutopulationshelters

L-101

ACTIVITIES

SHIELDING PROV:DES PROTECTION AGAINST NUCLEAR RADIATION

In planning for protection against nuclear radiation, time,

distance,and shielding must be considered. Shielding is the placing

of a mass of material betweenthe individual and the source of

radiation.

Different materials provide varying degrees of protection.

The degree of protection is measured by a protection factor which

is the amount by which shielding reduces radiation in the shielded

area as compared to that in the surrounding exposed area. Thus a

protection factor of 10 would mean that the intensity level with

protection is one-tenth the level without prItection.

A minimum protection factor of 100 has been selected by Civil

Defense as a compromise between the maximum intensity level to

which an individual can becontinuously exposed without harm aad the

cost of providing such shielding.

A comparison of the mass of material which provides a pro-

tectLoi factor of 100 follows:

SHIe1DII1G WITH A PROTECTION FACTOR OF 100

1000 Yhr 10 r/hr

zego /-//4"(not bt/cu. ft.)

5TEEL 45,4"(490 112./cu.f

con/Caere 16-(;4414/cult)

(toolbicu.ERRni 24°

Material Thickness for Protection Factor or loo

5,3 9

L-102


MATERIALS

KEY WORDS

nrotection factor

L-103

ACTIV=I&S-

SHELTERS PROVIDE SHIELDING

Adequate protection against nuclear detonations involves a

place for shelter. The shielding can varr from a minimum compacttype of shelter to a suitably protected normal living space with all

the necessities and conveniences. In large cities, communityshelters are provided and stocked by Civil Defense. Pupils should

be aware of the need for shielding and be familiar with where to go

and what to do in an emergency.

A protective shelter should have a protective factor of 100.Discuss the protective factors offered in the homes shown below.

(

stonebrick

MM77,

Basements, as normally comstructed, usually have a protectionfactnr of 10 to 20 or more in small residences and 100 or more in

ma!i-story structures, depending upon whether the basement is com-

pletely underground or partially exposed.

Muc:1 investigation and study has led to the conclusion that aprotection factor of 100, if generally available, would afford an

acceptable and realistic degree o- protection against fallout for the

people of New York. This standard would prevent fatalities andserious illness under clmost any conditions of atcack which can

reasonably be anticipated.

Appendix

542

accelerationanalyzeanglesapplicationarea

balancebiased

KEY WORDS

BLOCK 0: ORIENTATION

lengthlimitations

massmattermeasuremolE.cules

observationscapacityCelsius' pressurecircle primarycircumference procedurecommunication protractorccinclusion pure numberconstantcontrol qualitativecorrelate quantitative

data ratedecimal system ratiodefine regulardegree relationshipderiveddimension sextant

scleequivalent solutionenergy speedevent standardexpression substantiateextensions summarize

synonymousFahrenheitforcefrequencyfundamental

generalizationgravity

hypothesis

temperaturetentativethermocouplethermometertime

universalunknown

illusion variableindependent velocityinertia vibrationinstruments volumeintervalinvestigation wavesirregular weight

kinetic

543

1.

KEY WO7DS

BLOCK I: FORCES AT WORK

accelerationacceleration of gravityactionArchimede's Principle

2.

newtonNewton's First Law of MotionNewton's Second Law of MotionNewton's Third Law of Motion

balanced force Pascal's LawBernoulli's Principle potentlal energybouyancy power

presurecompound machines pulleyconservation of energyconservation of momentum reaction

resistancedensity resistance armdirectiondisplacement (distance & direction) screwdisplacement (fluid volume) simple machines

speedefforteffort arm velocityenergyequilibrium watt

wedgeforce 1,,;eight

wheel and axlefluid work

work inputfulcrum work output

gravitation unbalanced forcegravity

inclined planeinertia

joule

kinetic energy

le7er

machinemagnitudemassmechanical advantagemomentum

BLOCK J:

absorbedaccelerateaccumulateacidactivityactivity seriesagitatingalkalialloyarbitraryasbestosatomatomic numberatomic weightattracticaaxisaverage

baseBernoulli's PrincipleBohrborrowbracketsbrittlenessburnburningbusiness-like

catalystcatharticchargechemical actionchemical balancechemical changechemical combinationchemica: decompositionchemical replacement.chemicallychemically united.classificationclassifycoagulationcoefficientscolorcolloidal dispersioncolloidscombining gasescombining ratiocommercialcomparison

KEY WORDS

THE CHEMISTRY OF MATTER

complexcompositioncompoundsconcentratedconcentrationconvertedcoolcounteractcrystal latticecrystalizecurve

deceleratedecompoedeficiencydefinitedetecteddigestiondirectionsdissolvingdistributiondouble replacementdrugsductilit

elasticityelectrical balanceelectricityelectrochemical serieselectronelectrostaticelementsendothermicenergyenergy levelenergy shellequationetchingevaporatingexchangeexothermicexpandsexplosionexplosivesexpressingextinguisher

familiesfertilizerfilterfilter paper

5 45

3.

filtrateforceformformationformulafundamental

gasgeneratorgraphgroups

halogenshardnessheatheterogeneoushomogeneous

identifiedillustrateimpenetrabilityincandescenceindicatorinertinert gaseinertiaindustrial processesinsolubleinternallyionirritateisolatedisotope

keykinetickindling temperature

law of mass acti nlendlibera edlightliquidliquifieslitmuslubricantluminous

magnetmagneticmalleabilitymassmass number

mattermembranesmetalmetallicmetalloidsmineralsmixturesmolecularmolesmotionmultiplier

natureneutralizenoble gasesnon-metalsnon-metallicnon-metallic oxidenon-polarneutralneutronnuclearnucleinucleonnucleusnumerical

odoropaqueorbitorganizeoriginaloxidationoxidizing

parenthesisperiodic tableperiodsphasephenopthaleinphysicalpolarpositivepotentialprecipitatepredictionpreservingpressurepropertiesproportionprotonpulverizingPyrex

54-8

rare gasesratereactreactantsreaction temperaturereagentreducedreducingreflectedresistantrespiratory tractrevolveringsrounding-off

saltsaturatedseasoningseriesshattershearsimple replacementsolidsolublesolubility curvesolubility graphsolubility tablesolutesolutionsolventspacespatulaspecificspudstandardstirringstopperstrainstressstructuresubscriptsubstancesufficientsupersaturatedsuspensionsymbol

temperaturetenacity

uniformunsaturatedunstable

velocityvisible

water softenerweightwhole numberwing top

54

5.

KEY WORDS

BLOCK K: ENERGY AT WORK

ampereamplitudeangle of incidenceangle of reflectionatomattract

boiling point

capacitorCelsiuscharged objectscharging by contaccharging by inductioncolorcondensationconductionconductorconservation of chargescontractionconvectioncurrent electricity

dry cell

electric circuitelectric coilelectric currentelectric energyelectric motorelectric powerelectrolyteselectronelectromagnetic radiationelectromagnetic spectruMelectrophoruselectroscopeelectrostatic forcesexpansion

Fahrenheitfixed points (thermometefreezing pointfrequencyfuel cell

galvanometergasgenerator

heatHertz

548

insulatorionized gases

joule

kilocaloriekilowatt-hour

Leydon jarlightliquidlongitudinal wave

magnetic fieldsmagnetismmelting point

neutronnucleus

ohm

parallel circuitpermanent magnetphotoelectric cellproton

radiatorreflectionrefractionrepelresistanceresonance

series circuitsolidsoundstatic electricitystorage battery

temperaturetemporary magnetthermocouplethermometertransfer of charges

uncharged objects

voltvoltagevoltaic cell

wattwavelength

6.

KEY WORDS

BLOCK L: LIVING WITH THE ATOM

absorbedaccelerationaffinityair burstalpha particleamplifiedA.M.U.anemiaapplicationapproximationarchaeologyartificiallyatom smasheratomicatomic bombatomic numberatomic pile

betabetatronblastblast waveboiling pointbombardbubble chamber

calcifyingcancercarbohydrate forma i nCarbon-14cataractschain reactionchargechamberchemical interactionschromatographic techniquecommunitycompression waveconcentrationconstant-frequency cyclotrrnconsumptioncontaminationcontrolled reactionconvalescencecriticalcyclotron

9

debrisdecaydecomposedecontaminationdeflecteddemarcationdetectingdetonationdeuterondeuteriumdevelopmentdiagnosedilutionsdischargedisperseddistillationsdisturbancesdosimeter

electrical energyelementsEinsteinelectrodeselectromagnetic waveselectronelectroscopeErzmo2emissionemitemulsionenergyequationsexcretionsexpansionexploreexplosionexposure doseextracellular

factorfalloutfertilizerfilmfiltratiorsfireballfissionfissionablefission productsfluorescence

7

fog dropletfoggingfossil fuelsfree neutronsfungicidefusefusion

gamma raysGeiger-Muller countergenetic

half-lifeharvestedheavy element

impurityincorporatedindirectlyingestinginhalinginjectedinsecticideintensityinstinctiveinverse-squar- lawionsionizationionizeirrigationisotope

kinetic e .ergykinetic studies

larvaelassitudelethalleukemialiberatelocal fallout

magnetic fieldmarketingmarrowmass-el-largemass-energy equationmass-numbermass-reductionmassesmaximum brilliancemegatonmetabolism

micronmillisecondminimizemoderatormulchesmutation

natural radia ionsnauseaneutralizesnuclearnuclear devicenuclear reactornucleonsnucleusnutrient

penetrationperiodic tablephenomenaphosphorphosphorescentphoto-multiplier tubePhotosynthesisphysiologypoint sourcepopulationprecautionsprecipitationspreservationpressureprevailingprimary decayprobabilityproduct testingpropertyprostationprotection factorproton synchrotonpulsation

quality controlquantitative

radiation sicknessradioactivityradioiodineradioisotopesreaction intermediarc;esreconnaisancerelationshiprelativistic effectrelic

53

renderedresidualroentgens

scientistsscintillationscrewwormsecondary decayself-sustainingseparation schemesseven-foldsheltersshieldingspecimenspeedspeed of lightspontaneouslystatisticalsteelsterilizationstratospheresubsidesubsurfacesuccumbssupersaturatedsurface burstsuper-heatedsymbolssynchrocyclotronsynthesis

tagged atomtechniquetechnologicalTheory of Relativitytherapeuticthermalthermonuclearthyroid glandthyroxinetime periodtolerancetracerstracktransmittedtransmutationtraversetropospheretumor

uncontrolledunstable

Van De Graffvaporvaporizedvelocityviscosityvisible light

reaction

generator

9.

,rs price - ed

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