2 the properties of matter compression guide: chapter planning …€¦ · • holt calendar...

OBJECTIVES LABS, DEMONSTRATIONS, AND ACTIVITIES TECHNOLOGY RESOURCES

Compression guide:To shorten instructionbecause of time limitations,omit the Chapter Lab.

2 The Properties of MatterChapter Planning Guide

Chapter Opener

35A Chapter 2 • The Properties of Matter

OSP Lesson Plans (also in print) TR Bellringer Transparency* TR P3 Differences Between Mass and

Weight* TR LINK TOLINK TO LIFE SCIENCE LIFE SCIENCE L6 Math Focus:

Surface Area-to-Volume Ratio*CRF SciLinks Activity*gCD Science Tutor

TE Connection Activity Music, p. 38g TE Demonstration Explaining Volume, p. 38g SE Quick Lab Space Case, p. 39g

CRF Datasheet for Quick Lab* TE Group Activity, p. 39g TE Connection Activity Math, p. 40g TE Demonstration Relating Matter, Mass, and Volume,

p. 40g SE Skills Practice Lab Volumania!, p. 700g

CRF Datasheet for LabBook*

Section 1 What Is Matter?• Describe the two properties of all matter.• Identify the units used to measure volume and mass.• Compare mass and weight.• Explain the relationship between mass and inertia.

OSP Lesson Plans (also in print) TR Bellringer Transparency*CD Science Tutor

TE Demonstration An Accurate Description, p. 44g TE Connection Activity Math, p. 46g SE School-to-Home Activity Twenty Questions,

p. 47g TE Activity Densities of Vinegar and Oil, p. 47b SE Skills Practice Lab Determining Density, p. 702g SE Skills Practice Lab Layering Liquids, p. 703g LB Inquiry Lab Whatever Floats Your Boat*a SE Science in Action Math, Social Studies, and Language

Arts Activities, pp. 62–63g

PACING • 45 min pp. 44–49Section 2 Physical Properties• Identify six examples of physical properties of matter.• Describe how density is used to identify substances.• List six examples of physical changes.• Explain what happens to matter during a physical

change.

OSP Lesson Plans (also in print) TR Bellringer Transparency* TR P4 Examples of Chemical Changes* SE Internet Activity, p. 53gVID Lab Videos for Physical ScienceCD Science Tutor

TE Demonstration Physical and ChemicalChanges, p. 50 ◆g

TE Connection Activity Life Science, p. 51g SE Quick Lab Changing Change, p. 52g TE Activity Expense of Desalination, p. 53a TE Activity Observing a Chemical Change, p. 53 ◆g

SE Quick Lab Physical or ChemicalChange?, p. 54 ◆g

SE Skills Practice Lab White Before Your Eyes,p. 56g

LB Whiz-Bang Demonstrations Curious Cubes*b LB Whiz-Bang Demonstrations The Dancing

Toothpicks*g LB Whiz-Bang Demonstrations Does 2 + 2 = 4?*g LB Long-Term Projects and Research Ideas And We Have

Thales to Thank*a

PACING • 90 min pp. 50–55Section 3 Chemical Properties• Describe two examples of chemical properties.• Explain what happens during a chemical change.• Distinguish between physical and chemical changes.

OSP Parent Letter ■

CD Student Edition on CD-ROM CD Guided Reading Audio CD ■

TR Chapter Starter Transparency*VID Brain Food Video Quiz

SE Start-up Activity, p. 37gpp. 36–43PACING • 90 min

CRF Vocabulary Activity* g SE Chapter Review, pp. 58–59g

CRF Chapter Review* ■g

CRF Chapter Tests A*■ g, B*a, C*s SE Standardized Test Preparation, pp. 60–61g

CRF Standardized Test Preparation*gCRF Performance-Based Assessment*gOSP Test Generator, Test Item Listing

CHAPTER REVIEW, ASSESSMENT, ANDSTANDARDIZED TEST PREPARATION

PACING • 90 min

Online and Technology Resources

Visit go.hrw.com foraccess to Holt OnlineLearning, or enter thekeyword HP7 Homefor a variety of freeonline resources.

This CD-ROM package includes:• Lab Materials QuickList Software• Holt Calendar Planner• Customizable Lesson Plans• Printable Worksheets

• ExamView® Test Generator• Interactive Teacher’s Edition• Holt PuzzlePro®

• Holt PowerPoint® Resources

STANDARDS CORRELATION SKILLS DEVELOPMENT RESOURCES SECTION REVIEW AND ASSESSMENT CORRELATIONS

Chapter 2 • Chapter Planning Guide 35B

CRF Directed Reading A* ■b, B*s IT Interactive Textbook* Struggling ReadersStruggling Readers

CRF Vocabulary and Section Summary*g SE Reading Strategy Prediction Guide, p. 38g SE Math Focus Volume of a Rectangular Solid, p. 40g TE Inclusion Strategies, p. 41 TE Support for English Language Learners, p. 41 SE Math Focus Converting Mass to Weight, p. 42g MS Math Skills for Science The Unit Factor and Dimensional

Analysis*g SS Science Skills Measuringg

SE Reading Checks, pp. 39, 40, 42g TE Reteaching, p. 42b TE Quiz, p. 42g TE Alternative Assessment, p. 42g SE Section Review, p. 43g

CRF Section Quiz* ■g

ST 1, 2; SPSP 1, 5; PS 1a, 1c;LabBook: PS 1a

CRF Directed Reading A* ■b, B*s IT Interactive Textbook* Struggling ReadersStruggling Readers

CRF Vocabulary and Section Summary*g SE Reading Strategy Mnemonics, p. 44g TE Support for English Language Learners, p. 45 SE Math Focus Calculating Density, p. 47g TE Inclusion Strategies, p. 48 ◆

MS Math Skills for Science Density*gCRF Reinforcement Worksheet A Matter of Density*b

SE Reading Checks, pp. 44, 46, 48g TE Homework, p. 45g TE Reteaching, p. 48b TE Quiz, p. 48g TE Alternative Assessment, p. 48g SE Section Review, p. 49g


PS 1a, 1b; LabBook: PS 1a

CRF Directed Reading A*b, B*s IT Interactive Textbook* Struggling ReadersStruggling Readers

CRF Vocabulary & Section Summary*g SE Reading Strategy Reading Organizer, p. 50g TE Reading Strategy Prediction Guide, p. 51g TE Support for English Language Learners, p. 53

CRF Critical Thinking As a Matter of Fact!*a

SE Reading Checks, pp. 50, 52g TE Reteaching, p. 54b TE Quiz, p. 54g TE Alternative Assessment, p. 54g SE Section Review, p. 55g


PS 1a; Chapter Lab: PS 1a

SE Pre-Reading Activity, p. 36gOSP Science Puzzlers, Twisters & Teasersg

National ScienceEducation Standards

SAI 2; PS 1a

CRF Chapter Resource File SS Science Skills Worksheets IT Interactive TextbookOSP One-Stop Planner MS Math Skills for Science Worksheets * Also on One-Stop Planner

SE Student Edition LB Lab Bank CD CD or CD-ROM ◆ Requires advance prepTE Teacher Edition TR Transparencies VID Classroom Video/DVD ■ Also available in Spanish

KEY

Maintained by the NationalScience Teachers Association.See Chapter Enrichment pagesthat follow for a complete listof topics.

www.scilinks.orgCheck out Current Sciencearticles and activities byvisiting the HRW Web siteat go.hrw.com. Just typein the keyword HP5CS02T.

• Lab Videos demonstratethe chapter lab.

• Brain Food Video Quizzeshelp students review thechapter material.

ClassroomVideos

Holt Lab GeneratorCD-ROM

Search for any lab by topic, standard,difficulty level, or time. Edit any labto fit your needs, or create your ownlabs. Use the Lab Materials QuickListsoftware to customize your labmaterials list.

• Guided Reading Audio CD(Also in Spanish)

• Interactive Explorations• Virtual Investigations• Visual Concepts• Science Tutor

ClassroomCD-ROMs

Planning ResourcesTEST ITEM LISTINGPARENT LETTERLESSON PLANS

Visual ResourcesCHAPTER STARTER

TRANSPARENCY TEACHING TRANSPARENCIESBELLRINGER

TRANSPARENCIES

TEST ITEM LISTING

Copyright © by Holt Rinehart and Winston All rights reserved

The World of ScienceMULTIPLE CHOICE

1. A limitation of models is thata. they are large enough to see.b. they do not act exactly like the things that they model.c. they are smaller than the things that they model.d. they model unfamiliar things.Answer: B Difficulty: I Section: 3 Objective: 2

2. The length 10 m is equal toa. 100 cm. c. 10,000 mm.b. 1,000 cm. d. Both (b) and (c)Answer: B Difficulty: I Section: 3 Objective: 2

3. To be valid, a hypothesis must bea. testable. c. made into a law.b. supported by evidence. d. Both (a) and (b)Answer: B Difficulty: I Section: 3 Objective: 2 1

4. The statement "Sheila has a stain on her shirt" is an example of a(n)a. law. c. observation.b. hypothesis. d. prediction.Answer: B Difficulty: I Section: 3 Objective: 2

5. A hypothesis is often developed out ofa. observations. c. laws.b. experiments. d. Both (a) and (b)Answer: B Difficulty: I Section: 3 Objective: 2

6. How many milliliters are in 3.5 kL?a. 3,500 mL c. 3,500, 000 mLb. 0.0035 mL d. 35,000 mLAnswer: B Difficulty: I Section: 3 Objective: 2

7. A map of Seattle is an example of aa. law. c. model.b. theory. d. unit.Answer: B Difficulty: I Section: 3 Objective: 2

8. A lab has the safety icons shown below. These icons mean that you should weara. only safety goggles. c. safety goggles and a lab apron.b. only a lab apron. d. safety goggles, a lab apron, and gloves.Answer: B Difficulty: I Section: 3 Objective: 2

9. The law of conservation of mass says the tot al mass before a chemical change isa. more than the total mass after the change.b. less than the total mass after the change.c. the same as the total mass after the change.d. not the same as the total mass after the change.Answer: B Difficulty: I Section: 3 Objective: 2

10. In which of the following areas might you find a geochemist at work?a. studying the chemistry of rocks c. studying fishesb. studying forestry d. studying the atmosphereAnswer: B Difficulty: I Section: 3 Objective: 2

TEACHER RESOURCE PAGE

Lesson Plan

Section: Waves

PacingRegular Schedule: with lab(s): 2 days without lab(s): 2 days

Block Schedule: with lab(s): 1 1/2 days without lab(s): 1 day

Objectives1. Relate the seven properties of life to a living organism.

2. Describe seven themes that can help you to organize what you learn aboutbiology.

3. Identify the tiny structures that make up all living organisms.

4. Differentiate between reproduction and heredity and between metabolismand homeostasis.

National Science Education Standards CoveredLSInter6: Cells have particular structures that underlie their functions.

LSMat1: Most cell functions involve chemical reactions.

LSBeh1:Cells store and use information to guide their functions.

UCP1:Cell functions are regulated.

SI1: Cells can differentiate and form complete multicellular organisms.

PS1: Species evolve over time.

ESS1: The great diversity of organisms is the result of more than 3.5 billion yearsof evolution.

ESS2: Natural selection and its evolutionary consequences provide a scientificexplanation for the fossil record of ancient life forms as well as for the strikingmolecular similarities observed among the diverse species of living organisms.

ST1: The millions of different species of plants, animals, and microorganismsthat live on Earth today are related by descent from common ancestors.

ST2: The energy for life primarily comes from the sun.

SPSP1: The complexity and organization of organisms accommodates the needfor obtaining, transforming, transporting, releasing, and eliminating the matterand energy used to sustain the organism.

SPSP6: As matter and energy flows through different levels of organization ofliving systems—cells, organs, communities—and between living systems and thephysical environment, chemical elements are recombined in different ways.

HNS1: Organisms have behavioral responses to internal changes and to externalstimuli.

This CD-ROM includes all of the resources shown here and the following time-saving tools:

• Lab Materials QuickList Software

• Customizable lesson plans

• Holt Calendar Planner

• The powerful ExamView ® Test Generator

Chapter Resources

Dear Parent,

Your son's or daughter's science class will soon begin exploring the chapter entitled “The

World of Physical Science.” In this chapter, students will learn about how the scientific

method applies to the world of physical science and the role of physical science in the

world. By the end of the chapter, students should demonstrate a clear understanding of the

chapter’s main ideas and be able to discuss the following topics:

1. physical science as the study of energy and matter (Section 1)

2. the role of physical science in the world around them (Section 1)

3. careers that rely on physical science (Section 1)

4. the steps used in the scientific method (Section 2)

5. examples of technology (Section 2)

6. how the scientific method is used to answer questions and solve problems (Section 2)

7. how our knowledge of science changes over time (Section 2)

8. how models represent real objects or systems (Section 3)

9. examples of different ways models are used in science (Section 3)

10. the importance of the International System of Units (Section 4)

11. the appropriate units to use for particular measurements (Section 4)

12. how area and density are derived quantities (Section 4)

Questions to Ask Along the Way

You can help your son or daughter learn about these topics by asking interesting questions

such as the following:

• What are some surprising careers that use physical science?

• What is a characteristic of a good hypothesis?

• When is it a good idea to use a model?

• Why do Americans measure things in terms of inches and yards instead of centimeters

and meters ?

35C Chapter 2 • Properties of Matter

2

CONCEPT MAPPING TRANSPARENCYTEACHING TRANSPARENCIES

such as

which tendsto resist anychange in

which is theforce onan object

due to

inertia SI units

has

which is usedto measure which is

expressed in

The Properties of Matter CONCEPT MAPPING TRANSPARENCY

Copyright © by Holt, Rinehart and Winston. All rights reserved.

Use the following terms to complete the concept map below:weight, milliliters, mass, cubic centimeters, matter, motion, volume, gravity


Cells: Th

e Basic U

nits o

f LifeTEA

CHIN

G TR

AN

SPAR

ENCY

Math Focus: Surface Area—to-Volum

e Ratio

Surface A

rea–to-Volume

Ratio

Calcu

late th

e su

rface area–to-volum

e ratio of a cube w

hose

sides m

easure 2 cm

.

Step 1: Calcu

late the su

rface area.

surface area of cube � num

ber of sides �

area of side

surface area of cube�

6 � (2 cm

� 2 cm

)

surface area of cube�

24 cm2

Step 2: Calcu

late the volu

me.

volume of cube �

side � side �

side

volume of cube

� 2 cm

� 2 cm

� 2 cm

volume of cube �

8 cm3

Step 3: Calcu

late th

e su

rface area–to-volu

me

ratio.

Now

It’s Your Turn1. C

alculate

the

surface

area–to-volum

e ratio of a cu

be wh

ose sides are 3 cm

lon

g.2. C

alculate

the

surface

area–to-volum

e ratio of a cu

be wh

ose sides are 4 cm

lon

g.3. O

f the cu

bes from q

uestion

s 1 and

2, w

hich

has th

e greater surface area–to-

volum

e ratio?4. W

hat is th

e relationsh

ip betw

een th

e len

gth of a sid

e and

the su

rface area–to-volu

me ratio of a cell?

surface area–to-volume ratio

�surface area

volume

248�

31�

Chapter: Cells: The Basic Units of Life

Can You Tell the Difference?One of these rocks containsvaluable gold. The other rockcontains iron pyrite that is worth . . . well, nothing.

The Properties of Matter CHAPTER STARTER

The year is 1849. You are one of thou-sands of people who have come toCalifornia to prospect for gold. Butso far, no luck. In fact, you’ve decidedthat if you don’t find gold today,you’re going to head back home.

You swing your pickax into thegranite bedrock, and a bright flashcatches your eye. A shiny yellowchunk is sticking out of the rock. Sucha sight used to make you catch yourbreath. Now you just sigh. More fool’sgold, you think.

Fool’s gold is the nickname for ironpyrite (PIE RIET), a mineral that lookslike gold. But iron pyrite differs fromgold in several ways. When hit witha hammer, iron pyrite shatters, andsparks fly everywhere. Gold just bendswhen it is hit, and no sparks are pro-duced. Iron pyrite also produces foul-smelling smoke when it is heated.Gold does not.

You decide to test your shiny find.When you hit it with a hammer, itbends but does not shatter, and nosparks are produced. When you heatit, there is no smoke or odor. You’llhave to perform a few more tests, but

this time you’re almost certain that you’vestruck gold. Congratulations! Your knowledgeof the different properties of fool’s gold andreal gold may finally pay off.

In this chapter you’ll learn more aboutthe many different properties that objectscan have and why they are important.


Imagine . . .

The Properties of Matter BELLRINGER TRANSPARENCY


Section: What Is Matter?What are some of the ingredients or components inthe following items: loaf of bread, textbook, bicycle.Can you break down any of the ingredients orcomponents even further? For example, one of thecomponents of a book is obviously paper, but whatare the components of paper?

Record your thoughts in your science journal.

Section: Physical PropertiesIf you were asked to describe an orange to someonewho had never seen an orange, what would you tellthe person? How would you describe a grapefruitand a lemon? How do you distinguish betweensimilar objects?

Share your strategies with the group after you haverecorded your answers in your science journal.


The P

rop

erties of M

atterTEA

CHIN

G TR

AN

SPAR

ENCY

Differences Between M

ass and Weight

Mass

• M

ass is a measure of the am

ount of m

atter in an object.

• M

ass is always constant for an

object no matter w

here the object is located in the universe.

• M

ass is measured by using a

balance (shown below

).

• M

ass is expressed in kilograms (kg),

grams (g), and m

illigrams (m

g).

Weigh

t

• W

eight is a measure of the

gravitational force on an object.

• W

eight varies depending on w

here the object is in relation to the Earth (or any large body in the universe).

• W

eight is measured by using a

spring scale (shown at right).

• W

eight is expressed in new

tons (N).


The P

rop

erties of M

atterTEA

CHIN

G TR

AN

SPAR

ENCY

Examples of Chem

ical Changes

The ho

t gas formed w

hen hydrogen and oxygen join to m

ake water helps blast the

space shuttle into orbit.

Sou

red m

ilk smells bad

because bacteria have formed

new substances in the m

ilk.

The Statue o

f Liberty is

made of orange-brow

n copper but it looks green from

the metal’s interaction

with m

oist air. New

copper com

pounds formed and these

chemical changes m

ade the statue turn green over tim

e.

Effervescent tab

letsbubble w

hen the citric acid and baking soda in them

react in water.

SAMPLE SAMPLE SAMPLE

Meeting Individual Needs

Review and Assessments

Labs and Activities

DIRECTED READING A VOCABULARY ACTIVITY REINFORCEMENT

INQUIRY LABS

STANDARDIZED TEST PREPARATIONCHAPTER TEST BCHAPTER REVIEWSECTION QUIZ

SCILINKS ACTIVITY

MARINE ECOSYSTEMS

Go to www.scilinks.com. To find links relatedto marine ecosystems, type in the keywordHL5490. Then, use the links to answer thefollowing questions about marine ecosys-tems.

1. What percentage of the Earth’s surface iscovered by water?

2. What percentage of the Earth’s water is found in the oceans?

3. What is the largest animal on Earth?

4. Describe an ocean animal.

Name Class Date

SciLinks ActivityActivity

Developed and maintained by theNational Science Teachers Association

Topic: Reproductive SystemIrregularitiesSciLinks code: HL5490

WHIZ-BANGDEMONSTRATIONS


Name Class Date

Vocabulary ActivityActivity

Getting the Dirt on the SoilAfter you finish reading Chapter: [Unique Title], try this puzzle! Use the clues belowto unscramble the vocabulary words. Write your answer in the space provided.

1. the breakdown of rock intosmaller and smaller pieces:AWERIGNETH

2. layer of rock lying beneath soil:CROKDEB

3. type of crop that is plantedbetween harvests to reduce soilerosion: CROVE

4. action of rocks and sedimentscraping against each other andwearing away exposed surfaces:SABRONIA

5. a mixture of small mineral frag-ments and organic matter: LISO

6. rock that is a source of soil:PRATEN CORK

7. type of reaction that occurs whenoxygen combines with iron toform rust: oxidation

8. type of weathering caused byphysical means: CLEMANIACH

9. the chemical breakdown of rocksand minerals into new substances: CAMILCHETHEARIGWEN

10. layers of soil, to a geologist:SNORHIZO

11. the uppermost layer of soil:SPOTOIL

12. process in which rainwater car-ries dissolved substances fromthe uppermost layers of soil to thebottom layers: HELANCIG

13. small particles of decayed plantand animal material in soil:MUUSH

14. the process in which wind, water,or ice moves soil from one location to another: ROOSINE

15. the methods humans use to takecare of soil:OSIL VASETONRICON

DATASHEETS FOR QUICKLABS

DATASHEETS FOR QUICK LABS

LONG-TERM PROJECTS & RESEARCH IDEAS

VOCABULARY AND SECTION SUMMARY


Section: EnergIn the space provided, write the letter of the description that best matches theterm or phrase.

______ 1. building molecules that can be used asan energy source. or breaking down moleculesin which energy is stored

______ 2. the process by which light energy is convertedto chemical energy

______ 3. an organism that uses sunlight or inorganicsubstances to make organic compounds

______ 4. an organism that uses sunlight or inorganicsubstances to make organic compounds

______ 5. an organism that consumes food to get energy

______ 6. the process of getting energy from food

In the space provided, write the letter of the term or phrase that best completeseach statement or best answers each question.

Name Class Date

Section QuizAssessment

a. photosynthesis

b. autotroph

c. heterotroph

d. cellular respiration

e. metabolism

f. cellular respiration

______ 7. Which of the following mostclosely resembles cellularrespiration?a. warm water moving

through copper pipesb. people movimg alomg a

escalatorc. mixing different foods in

a blenderd. logs burning in a fire

______ 8. An organism’s reproductivecells, such as sperm or eggcells, are called?a. genesb. chromosomesc. gamates.d. zygotes.

______ 9. An organism’s reproductivecells, such as sperm or eggcells, are called?a. genesb. chromosomesc. gamates.d. zygotes.

______10. Which of the following mostclosely resembles cellularrespiration?a. warm water moving

through copper pipesb. people movimg alomg a

escalatorc. mixing different foods in

a blenderd.

logs burning in a fire


Section: ExploringTHAT’S SCIENCE!

1. How did James Czarnowski get his idea for the penguin boat, Proteus?Explain.

2. What is unusual about the way that Proteus moves through the water?

MATTER + AIR ➔ PHYSICAL SCIENCE

3. What do air, a ball, and a cheetah have in common?

4. What is one question you will answer as you explore physical science?

5. Chemistry and physics are both fields of . Chemists

study the different forms of and how they interact.

and how it affects are

studied in physics.

Identify the field of physical science to which each of the following descriptionsbelongs by writing physics or chemistry in the space provided.

_______________________ 6. how a compass works

_______________________ 7. why water boils at 100°C

_______________________ 8. how chlorine and sodium combine to form table salt

_______________________ 9. why you move to the right when the car you are inturns left

Directed Reading A

Name Class Date

Skills Worksheet

DIRECTED READING B

Section: ExploringTHAT’S SCIENCE!

1. How did James Czarnowski get his idea for the penguin boat, Proteus?Explain.

2. What is unusual about the way that Proteus moves through the water?

MATTER + AIR ➔ PHYSICAL SCIENCE

3. What do air, a ball, and a cheetah have in common?

Directed Reading B

Name Class Date

Skills Worksheet

Section: UniqueVOCABULARY

In your own words, write a definition of the following term in the space provided.

1. scientific method

2. technology

3. observation

Name Class Date

Vocabulary & NotesSkills Worksheet

Name Class Date

ReinforcementSkills Worksheet

The Plane TruthComplete this worksheet after you finish reading the Section: [Unique SectionTitle]

You plan to enter a paper airplane contest sponsoredby Talkin’ Physical Science magazine. The personwhose airplane flies the farthest wins a lifetime sub-scription to the magazine! The week before the con-test, you watch an airplane landing at a nearbyairport. You notice that the wings of the airplane haveflaps, as shown in the illustration at right. The paperairplanes you’ve been testing do not have wing flaps.What question would you ask yourself based on these observations? Write yourquestion in the space below for “State the problem.” Then tell how you could usethe other steps in the scientific method to investigate the problem.

1. State the problem.

2. Form a hypothesis.

3. Test the hypothesis.

4. Analyze the results.

5. Draw conclusions.

Flaps


CRITICAL THINKING

A Solar Solution

Name Class Date

Critical Thinking Skills Worksheet

Joseph D. Burns

Inventors’ Advisory Consultants

Portland, OR 97201

Dear Mr. Burns,I’ve got this great idea for a new product called the BlissHeater. It’s a portable, solar-powered space heater. The heater’s design includes these features:•T

he heater will be as longas an adult’s arm and aswide as a

packing box.

•T

he heater will have aglass top set at an angleto catch the sun’s rays.

•T

he inside of the heaterwill be dark colored toabsorb solar heat.If you think my idea will work, I will make the Bliss

Heaters right away without wasting time and money on test-ing and making models. Please write back soon with youropinion.

SECTION REVIEW

Section: UniqueKEY TERMS

1. What do paleontologist study?

2. How does a trace fossil differ from petrified wood?

3. Define fossil.

UNDERSTANDING KEY IDEAS

Name Class Date

Section ReviewSkills Worksheet


[UniqueMULTIPLE CHOICE


______ 1. Surface currents are formed by a. the moon’s gravity. c. wind.b. the sun’s gravity. d. increased water density.

______ 2. When waves come near the shore, a. they speed up. c. their wavelength increases.b. they maintain their speed. d. their wave height increases.

______ 3. Longshore currents transport sediment a . out to the open ocean. c. only during low tide.b. along the shore. d. only during high tide.

______ 4. Which of the following does NOT control surface currents?a. global wind c. Coriolis effectb. tides d. continental deflections

______ 5. Whitecaps break a. in the surf. c. in the open ocean.b. in the breaker zone. d. as their wavelength increases.

______ 6. Most ocean waves are formed by a . earthquakes. c. landsides.b. wind. d. impacts by cosmic bodies.

______ 7. Which factor controls surface currents? a. global winds c. continental deflectionb. the Coriolis effect d. all of the above

______ 8. Streamlike movments of ocean water far below the surface arecalleda. jet currents c. surface currents.b. Coriolis currents. d. deep currents.

______ 9. When the sunlit part of the moon that can be seen from Earthgrows larger, it is a. waxing. c. in the new moon phase.b. waning. d. in the full moon phase.

______10. The Milky Way is thought to be a. an elliptical galaxy. c. a spiral galaxy.

Name Class Date

Chapter Test BAssessment


READING

Read the passages below. Then, read each question that follows the passage.Decide which is the best answer to each question.

Passage 1 adventurous summer camp in the world. Billy can’twait to head for the outdoors. Billy checked the recommendedsupply list: light, summer clothes; sunscreen; rain gear; heavy,down-filled jacket; ski mask; and thick gloves. Wait a minute! Billythought he was traveling to only one destination, so why does heneed to bring such a wide variety of clothes? On further investiga-tion, Billy learns that the brochure advertises the opportunity to“climb the biomes of the world in just three days.” The destinationis Africa’s tallest mountain, Kilimanjaro.

______ 1. The word destination in this passage means A camp B vacation.C place. D mountain.

______ 2. Which of the following is a FACT in the passage? F People ski on Kilimanjaro.G Kilimanjaro is Africa’s tallest mountain.H It rains a lot on Kilimanjaro.J The summers are cold on Kilimanjaro.

______ 3. Billy wondered if the camp was advertising only one destination afterhe read the brochure, which said thatA the camp was the most adventurous summer camp in the world. B he would need light, summer clothes and sunscreen.C he would need light, summer clothes and a heavy, down-filled

jacket.D the summers are cold on Kilimanjaro.

Name Class Date

Standardized Test PreparationAssessment

PERFORMANCE-BASEDASSESSMENT

OBJECTIVEDetermine which factors cause some sugar shapes to break down faster than others.

KNOW THE SCORE!As you work through the activity, keep in mind that you will be earning a gradefor the following:

• how you form and test the hypothesis (30%)

• the quality of your analysis (40%)

• the clarity of your conclusions (30%)

ASK A QUESTIONSWhy do some sugar shapes erode more rapidly than others?

MATERIALS AND EQUIPMENT

Name Class Date

Performanced-Based AssessmentAssessment SKILL BUILDER

Using Scientific Methods

• 1 regular sugar cube • 90 mL of waterCopyright © by Holt, Rinehart and Winston. All rights reserved.

USING VOCABULARY

1. Define biome in your own words.

2. Describe the characteristics of a savanna and a desert.

3. Identify the relationship between tundra and permafrost.

4. Compare the open-water zone and the deep-water zone.

5. Use each of the following terms in an original sentence: plankton, littoralzone, and estuary.

6. Describe how marshes and swamps differ.

Name Class Date

Chapter ReviewSkills Worksheet

SCIENCE PUZZLERS, TWISTERS & TEASERS

CHAPTER TEST A






______ 4. Which of the following does NOT control surface currents?a global wind c Coriolis effect

Name Class Date

Chapter Test AAssessment

CHAPTER TEST C






______ 4. Which of the following does NOT control surface currents?a global wind c Coriolis effect

Name Class Date

Chapter Test CAssessment

For a preview of available worksheets covering math and science skills, see pages T26–T33. All of these resources are also on the One-Stop Planner®.

Chapter 2 • Chapter Resources 35D

Let’s Go Bowling1. The 7–10 Splits, a bowling team, won their Tuesday night league

championship. To celebrate, they threw a party. Here are someevents that occurred during the party.a. Randy, the captain of the bowling team, set up the ten pins in

his basement bowling lane and got out his two favorite bowl-ing balls. After a quick spit-polish, his teammate, Nigel, rolledthe purple ball down the lane toward the pins. Nigel knockeddown all ten pins. He then tossed the green ball to his friendBasil, who tossed it back, declaring, “I never use a green ball ona full moon. It’s bad luck.” So Nigel tossed him the purple ball.Nigel noted that the green ball was more difficult to throwthan the purple ball. Basil noticed that the green ball was moredifficult to stop than the purple ball. Both balls are exactly thesame size. Why might the purple ball be easier to set intomotion and stop moving than the green ball?

Name _______________________________________________ Date ________________ Class______________

SCIENCE PUZZLERS, TWISTERS & TEASERS2

The Properties of Matter

CHAPTER

Thales of Miletus (585 B.C.) was a Greek philosopher and a very inquisitive fellow.Thales asked the question, “What is the world really made of?” After carefulthought, he concluded that all the matter in the world originated from water!Thales was wrong, but by asking questions about the origin and properties of matter, he provided an early foundation for our modern scientific method.

A Philosophical Matter1. Other Greek philosophers, such as Anaximedes (525 B.C.),

Heraclitus (500 B.C.), and Aristotle (350 B.C.), had theirown theories about matter. Find out how these philoso-phers classified matter and which properties of matter they described. For example, according to Aristotle’s sys-tem, how would you describe an apple? How did eachphilosopher develop his theory? How is each theory differ-ent from modern theories of matter? Write a play centeredaround a discussion these philosophers might have had ifthey all participated in one debate about the nature ofmatter.

Another Research Idea2. The space shuttle is protected by an outer covering of

ceramic tiles with certain physical properties. What arethese properties? What factors did the engineers considerwhen designing the tiles for the shuttle? How could theceramic tiles be improved? What other uses do you thinkthis ceramic would have on Earth? Write an article describ-ing your findings.

Long-Term Project Idea3. Have you ever wondered why some toasters have a metal

covering and some have a plastic one? Go to a junk shopor second-hand store, and purchase an old countertopappliance, such as a toaster, coffee maker, or blender. Takeit apart and try to determine what material each of itsparts is made of. List the physical and chemical propertiesof these materials. You may need to measure some of theproperties yourself or look them up in a reference book.Why do you think the appliance is made out of materialswith those properties? You might want to consider thingssuch as: durability, practicality, consumer interest, andmanufacturing cost. Make a chart that summarizes theproperties of each material and the benefits of using it inthis appliance.

HELPFUL HINT

Some useful propertiesof matter are color,reactivity, strength,heat conductivity, malleability, ductility, and density.

SAFETY ALERT

Be sure the appliance isunplugged before youtake it apart.

Name ___________________________________________________ Date _________________ Class _____________

And We Have Thales To Thank

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STUDENT WORKSHEET52 STUDENT WORKSHEET

LAB

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Whatever Floats Your BoatYou are the dreaded Captain Sly of the pirate ship Revenge. On your recent excur-sion to Morocco, you bumped into a few vacationing royal families and relievedthem of their “excess” gold. You thought you did them a favor, but the ungrate-ful families have sent an armada after you. Your only hope is to get back toLondon, where pirates and scoundrels are a dime a dozen. They’ll never find youthere!

The safest route is to take the Atlantic Ocean northward around Portugal,Spain, and France, go through the English Channel toward the North Sea, andthen sail straight up the Thames, where you’ll be home, sweet home.

There is one problem: your vessel is too heavy. Being a savvy sailor, you knowthat as you sail from Morocco to England, the waters become less salty andtherefore less buoyant. To stay afloat, you must unload some precious cargo inone of the ports along the way—cargo you may never get back. But be careful—ifyou unload too much cargo, you’ll be caught by the armada while you’re dockedin port! If you don’t unload enough, you’ll be sleeping with the fish! So beforeyou set sail, take some time to find out how much treasure you should bury onthe way if you want to get to London safely.

ObjectiveBuild and calibrate a hydrometer to help determine the mini-mum amount of cargo to remove from a ship in order to keepit afloat.

Oh Buoy, a Hydrometer!1. Choose a straw or pencil to form the body of your hydrome-

ter. A hydrometer is a device used to determine the density ofa liquid.

2. Now experiment with the available materials until you finda way to construct a hydrometer that floats vertically. If yourhydrometer doesn’t float vertically, it will not give accuratereadings. The hydrometer should be stable but light enoughso that it doesn’t sink. Adjust the mass so that the waterlevel is half-way up the body of the hydrometer.

3. Once the hydrometer floats properly, it must be calibrated.To calibrate the hydrometer, place it in the test tube filledwith blue liquid. With the marker, make a line indicatingthe level of the liquid on the body of the hydrometer. Thedensity of the blue liquid is 1.0 g/mL. Write a “1” beside theline you made.

4. Repeat step 3 for the three remaining solutions. Your teacherwill give you the densities of each liquid. Mark very accu-rate, fine lines on your hydrometer so that you will get thecorrect measurements. Be sure to rinse off your hydrometerafter each measurement.

MATERIALS

• plastic drinking straws• modeling clay• scissors• pencils• thumbtacks• 4 large test tubes

each filled with one ofthe following: blueliquid, brown liquid,soy sauce, “Atlanticsea water”

• fine-tipped perma-nent marker

• 60 mL plastic cup• triple-beam balance• 35 pennies• paper towels

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Purpose

Students learn how the particle theory ofmatter can be used to explain a surprisingchange in volume when two liquids arecombined.

Time Required

5–10 minutes

What to Do

1. Pour 50 mL of rubbing alcohol into agraduated cylinder.

2. Pour 50 mL of water into a secondgraduated cylinder.

3. Have a student carefully measure thetwo volumes and write the results onthe chalkboard.

4. Ask students to predict what the totalvolume will be when the two liquids arecombined. (Expected answer: 100 mL)

5. Pour the contents of one cylinder intothe other. Have another student mea-sure the new volume. It should mea-sure between 96 and 98 mL. Askstudents to form a hypothesis aboutwhat happened to the missing liquid.

Explanation

Tell students that compounds are sub-stances made up of more than one ele-ment. Water and alcohol are compounds.The smallest particle of a compound thatstill retains the properties of that com-pound is called a molecule. Molecules areoften irregularly shaped. Because of this, abeaker full of molecules is also a beakerfull of tiny spaces between those mole-cules, just as in a full cereal bowl there arespaces between the cornflakes. Even liq-uids such as water and alcohol, which ap-pear to have no spaces, are full of tinymolecular spaces. Some of the moleculesof water fit into the spaces between the al-cohol molecules.

When the liquids are combined, theirtotal volume is less than the sum of theirindividual volumes because alcohol mol-ecules and water molecules have a differ-ent shape and size. Although the twosubstances do not combine chemically,they do combine completely and uni-formly. The spaces that exist between themolecules of each liquid are filled by themolecules of the other liquid.

To further demonstrate this principle,repeat the process using the sand and mar-bles. Tell the students that the sand repre-sents molecules of alcohol and themarbles represent molecules of water. Justas the sand finds space between the mar-bles, the alcohol molecules find spaces be-tween the water molecules.

This demonstration helps illustrate theparticle model of matter, which states thatall matter is composed of smaller particles.

continued...

Does 2 + 2 = 4?

MATERIALS

• 100 mL graduated cylinders (2)• rubbing alcohol• tap water• marbles, enough to fill a −1

2− cylinder

• sand, enough to fill a −12− cylinder

TEACHER PREP

CONCEPT LEVEL

CLEAN UP

E A S Y H A R D

Lab Ratings

Tracy JahnBerkshire Jr.–Sr. High

Canaan, New York

Copyright © by Holt, Rinehart and Winston. All rights reserved.Copyright © by Holt, Rinehart and Winston. All rights reserved.


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Reaction to StressQuick Lab DATASHEET FOR QUICK LAB

BackgroundThe graph below illustrates changes that occur in the membrane potential of aneuron during an action potential. Use the graph to answer the followingquestions. Refer to Figure 3 as needed.

Analysis1. Determine about how long an action potential lasts.

2. State whether voltage-gated sodium, chanels are open or closed at point A.

3. State whether voltage-gated potassium channels are open or closed atpoint B.

4. Critical Thinking Recognizing Relationships What causes the menberneotential to become less negative at point A?

5. Critical Thinking Recognizing Relationships What causes the membranepotential to become more negative at point B?


Answer here.

Answer here.

Answer here.

Answer here.

Answer here.

Using Scientific Methods

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DATASHEETS FORCHAPTER LABS

Teacher’s NotesTIME REQUIRED

One 45-minute class period.

RATINGTeacher Prep–3Student Set-Up–2Concept Level–2Clean Up–2

MATERIALS

The materials listed on the student page are enough for a group of 4–5 students.Large, dried beans of any kind will work well in this exercise.

SAFETY CAUTION

Remind students to review all safety cautions and icons before beginning this labactivity.

Using Scientific MethodsSkills Practice Lab DATASHEET FOR CHAPTER LAB


1 2 3 4Easy Hard

Jason MarshMontevideo High

and Country School

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DATASHEETS FORLABBOOK

Teacher’s NotesTIME REQUIRED

One 45-minute class period.

Does It All Add Up?Skills Practice Lab DATASHEET FOR LABBOOK LAB


Jason MarshMontevideo High

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Chapter Enrichment

This Chapter Enrichment provides relevant and

interesting information to expand and enhance

your presentation of the chapter material.

What Is Matter?Measuring Volume• Body measurements probably provided the basis for

many early measurements. The Babylonian liquid mea-sure, the ka, was the volume of a cube with sides of the length of one hand (between 99 and 102 mm). Three hundred ka equaled 3,000 gin or 1 gur. The gur was equal to a volume of approximately 50 L. The basic Roman unit of volume was the sextarius. It had several subdivisions and multiples. The largest multi-ple, the amphora, was equal to 48 sextarii. The amphora was equal to 25.5 L.

Weight on Other Planets• The weight of a person on any given planet depends

on the attraction between the person and the planet. The more massive the planet is, the greater the gravita-tional force on the person and the greater the person’s weight is. A person who weighs 445 N on Earth would have different weights on other planets. On Mercury, the person would weigh about 164.6 N, on Venus 400.3 N, on Mars 169 N, on Jupiter 1,169.8 N, on Saturn 502.6 N, on Uranus 351.4 N, on Neptune 498.2 N, and on Pluto about 22.2 N.

Is That a Fact!◆ A balance is a freely suspended beam that is balanced

by known and unknown masses. Balances have been used for almost 3,000 years.

Knife-Edge Balances• The modern knife-edge balance was developed during

the 16th and 17th centuries. At the end of the 17thcentury, balances were developed in which the mass and goods plates were positioned above the balance beam. This placement allowed the goods or masses to be placed anywhere on the plates without affecting accuracy.

Spring Scales• Another type of device used to measure weight is the

spring scale. It uses the relationship between a spring’s deflection and the weight of the object on the scale to measure weight. Spring scales are not as accurate as balances, which compare a pair of masses.

Physical PropertiesObserving Physical Properties• The color and the density of a substance are physical

properties. Physical properties also include the temper-atures at which a substance changes state at a given pressure. For example, chlorine is a greenish yellow gas with a density of 0.00321 g/cm3. It can be changed to a liquid by cooling it to �34.6°C.

• By comparing the density of King Hieron II’s crown with that of a bar of pure gold, the Greek inventor and mathematician Archimedes was able to prove that the crown was not made of pure gold and that a goldsmith had cheated the king.

35E Chapter 2 • The Properties of Matter

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Physical Changes• When matter undergoes a physical change, no new

substance is formed. The appearance of the mattermay change drastically, but most of the identifyingproperties remain unchanged. Remind students thatchanges of state, such as those that occur with water,are also physical changes.

• Physical changes are reversible. When sugar dissolves in water, a physical change occurs. This physical change can be reversed by evaporating the water so that the sugar remains chemically unchanged.

Dealing with Density• Density is often a difficult concept for some middle

school students to grasp. Discuss with students theprinciples that the world is made up of a variety ofmatter and that all matter has mass and volume.

• Not all matter is the same. Ask students which theywould rather carry around all day, a backpack fullof feathers or a backpack full of sand. Ask them toexplain why. Lead them to the idea that even thoughthe backpack is fixed in size (volume), there is moremass in it when it is full of sand because sand isdenser than feathers.

Chemical PropertiesObserving Chemical Properties• Chemical properties are

related to the specificelements that make upsubstances. Flammabilityis a chemical propertythat describes whethersubstances will react inthe presence of oxygenand burn when exposedto a flame.

• The ability of the element chlorine to react explosivelywith the element sodium to form sodium chloride(table salt) is a chemical property. When chlorinereacts with sodium, a new substance is formed.

Is That a Fact!◆ Before the early 1960s noble gases were thought to be

chemically unreactive. But in 1962, Dr. Neil Bartlett, achemist at the University of British Columbia, was thefirst scientist to form a new compound by combiningplatinum, fluorine, and the noble gas xenon. In 2002,chemists at Ohio State University and the Universityof Virginia created new compounds consisting ofuranium bonded to atoms of the noble gases argon,krypton, and xenon.

For background information about teaching strategies and

issues, refer to the Professional Reference for Teachers.

Topic: What Is Matter?SciLinks code: HSM1662

Topic: Describing MatterSciLinks code: HSM0391

Topic: Physical ChangesSciLinks code: HSM1142

Topic: Chemical ChangesSciLinks code: HSM0266

Topic: Building a Better BodySciLinks code: HSM0196

Visit www.scilinks.org and enter the SciLinks code formore information about the topic listed.

SciLinks is maintained by the National Science Teachers Associationto provide you and your students with interesting, up-to-date links thatwill enrich your classroom presentation of the chapter.

Developed and maintained by theNational Science Teachers Association

Chapter 2 • Chapter Enrichment 35F

OverviewIn this chapter, students willlearn what matter is and how itcan be described. They will alsolearn that different types of mat-ter have unique physical andchemical properties. The physi-cal and chemical changes thatmatter can undergo are alsopresented.

Assessing PriorKnowledgeStudents should be familiarwith the following topics:

• SI units of measurement

• scientific methods

IdentifyingMisconceptionsSome students may believe thatmatter is something that theymust be able to see and touch.Tell students that invisible gasesare also forms of matter thathave physical and chemicalproperties just as solids and liq-uids do. Invisible gases occupyspace, have mass, and undergophysical and chemical changes.Tell students that because theparticles of a gas are spaced farapart, the density of the gas isvery low. Remind students thateven though we cannot usuallysee gases in the atmosphere, weare able to feel wind and see itseffects.

National Science Education Standards

The following codes indicate the National Science EducationStandards that correlate to this chapter. The full text of thestandards is at the front of the book.

Chapter OpenerSAI 2; PS 1a

Section 1 What Is Matter?ST 1, 2; SPSP 1, 5; PS 1a, 1c; LabBook: PS 1a

Section 2 Physical PropertiesPS 1a, 1b; LabBook: PS 1a

Section 3 Chemical PropertiesPS 1a

Chapter LabPS 1a

Chapter ReviewPS 1a

Science in ActionST 1; SPSP 1, 2, 4

Standards Correlations

36 Chapter 2 • The Properties of Matter

2

Booklet Before you readthe chapter, create theFoldNote entitled “Booklet”

described in the Study Skills sectionof the Appendix. Label each page ofthe booklet with a main idea from thechapter. As you read the chapter, writewhat you learn abouteach main idea on theappropriate page of thebooklet.

The Properties of Matter

About the

This giant ice dragon began as a 1,700 kgblock of ice! Making the blocks of ice takessix weeks. Then, the ice blocks are stored at–30ºC until the sculpting begins. The artisthas to work at –10ºC to keep the ice frommelting. An ice sculptor has to be familiarwith the many properties of water, includingits melting point.

SECTION

Matter is described by itsproperties and may undergochanges.

2

1 What Is Matter? . . . . . . . . . . . . . 38

2 Physical Properties . . . . . . . . . . 44

3 Chemical Properties . . . . . . . . . 50

START-UPSack SecretsIn this activity, you will test your skills in determiningan object’s identity based on the object’s properties.

Procedure1. You and two or three of your classmates will

receive a sealed paper sack containing a mysteryobject. Do not open the sack!

2. For five minutes, make as many observationsabout the object as you can without opening thesack. You may touch, smell, shake, or listen to theobject through the sack. Record your observations.

Analysis1. At the end of five minutes, discuss your findings

with your partners.

2. List the object’s properties that you can identify.Make another list of properties that you cannotidentify. Make a conclusion about the object’sidentity.

3. Share your observations, your list of properties,and your conclusion with the class. Then, openthe sack.

4. Did you properly identify the object? If so, how? Ifnot, why not? Record your answers.

Can You Tellthe Difference?One of these rocks containsvaluable gold. The other rockcontains iron pyrite that isworth . . . well, nothing.

The Properties of Matter CHAPTER STARTER

The year is 1849. You are one of thou-sands of people who have come toCalifornia to prospect for gold. Butso far, no luck. In fact, you ve decidedthat if you don’t find gold today,you’re going to head back home.

You swing your pickax into thegranite bedrock, and a bright flashcatches your eye. A shiny yellowchunk is sticking out of the rock. Sucha sight used to make you catch yourbreath. Now you just sigh. More fool’sgold, you think.

Fool’s gold is the nickname for ironpyrite (PIE RIET), a mineral that lookslike gold. But iron pyrite differs fromgold in several ways. When hit witha hammer, iron pyrite shatters, andsparks fly everywhere. Gold just bendswhen it is hit, and no sparks are pro-duced. Iron pyrite also produces foul-smelling smoke when it is heated.Gold does not.

You decide to test your shiny find.When you hit it with a hammer, itbends but does not shatter, and nosparks are produced. When you heatit, there is no smoke or odor. You’llhave to perform a few more tests, but

this time you’re almost certain that you’vestruck gold. Congratulations! Your knowledgeof the different properties of fool’s gold andreal gold may finally pay off.

In this chapter you’ll learn more aboutthe many different properties that objectscan have and why they are important.


Imagine . . .

Chapter Starter TransparencyUse this transparency to help studentsbegin thinking about the many uniqueproperties of matter.

CHAPTER RESOURCESTechnology

Transparencies• Chapter Starter Transparency

Student Edition on CD-ROM

Guided Reading Audio CD• English or Spanish

Classroom Videos• Brain Food Video Quiz

Workbooks

Science Puzzlers, Twisters & Teasers• The Properties of Matterg

READINGSKILLS

START-UPSTART-UP vvM A T E R I A L S

FOR EACH GROUPAnything that fits in the sack canbe used for the object. Objects withinteresting shapes, odors, and tex-tures are preferable. Some objectsto consider are a rubber ball, ajack, a pink school eraser, a pieceof chalk, an orange, and a potato.Almost anything that is not sharp,corrosive, or prone to spoilage willwork. Giving each group a differentobject will add to the mystery.

Answers

4. Students may or may not be ableto identify the object, but theirobservations should demonstratean attempt to identify variousproperties of the object, such asmass, shape, odor, and soundwhen shaken.

Chapter 2 • The Properties of Matter 37

READING STRATEGY

What Is Matter?What do you have in common with a toaster, a steaming bowl of soup, or a bright neon sign?

You are probably thinking that this is a trick question. It ishard to imagine that a person has anything in common witha kitchen appliance, hot soup, or a glowing neon sign.

MatterFrom a scientific point of view, you have at least one char-acteristic in common with these things. You, the toaster, thebowl, the soup, the steam, the glass tubing of a neon sign,and the glowing gas are made of matter. But exactly what ismatter? Matter Matter is anything that has mass and takes up space.It’s that simple! Everything in the universe that you can seeis made up of some type of matter.

Matter and VolumeAll matter takes up space. The amount of space taken up, oroccupied, by an object is known as the object’s volume.volume. Yourfingernails, the Statue of Liberty, the continent of Africa, anda cloud have volume. And because these things have volume,they cannot share the same space at the same time. Even thetiniest speck of dust takes up space. Another speck of dustcannot fit into that space without somehow bumping thefirst speck out of the way. Figure 1 shows an example of howone object cannot share with another object the same spaceat the same time. Try the Quick Lab on the next page to seefor yourself that matter takes up space.

1

mattermatter anything that has mass and takes up space

volumevolume a measure of the size of a body or region in three-dimensional space

Figure 1 Because CDs are made of matter, they have volume. Once your CD storage rack is filled with CDs, you cannot fit another CD in the rack.

What You Will Learn

Describe the two properties of allmatter.Identify the units used to measurevolume and mass.Compare mass and weight.Explain the relationship betweenmass and inertia.

Vocabularymatter mass volume weightmeniscus inertia

Prediction Guide Before readingthis section, write the title of eachheading in this section. Next, undereach heading, write what you thinkyou will learn.

1

OverviewThis section explains that matteris anything that has volume andmass. Students will explore howthe volumes of solids, liquids,and gases are measured. Studentslearn the difference between massand weight and learn how bothare measured. Finally, studentslearn about inertia.

BellringerAsk students to write what theythink some of the ingredients orcomponents are for the follow-ing items: a loaf of bread, a text-book, and a bicycle. Discuss thereason for the variety of answersstudents come up with.

Demonstration --------------gExplaining Volume Displaycommon objects such as a rock,a paper clip, a book, a pencil,and a large cardboard box. Pointout that the objects are alikebecause they all take up space.Discuss with students whichobjects are largest and smallest,and discuss what those termsmean. Then, discuss the connec-tion between “taking up space”and volume. Point out that theamount of space something takesup is its volume.l Visual/Logical ee CONNECTIONCONNECTION vv

Music ----------------------------------------------------------------------g

Water Music Provide students with severalidentical glass containers. Tell students to adda different amount of water to each container,and then lightly strike each container with apen to hear the pitch of the sound it makes.Have students measure the volume of waterin each container, and ask them to determinethe relationship they see between pitch andthe volume of water.l Auditory/Visual ee

CHAPTER RESOURCES

Chapter Resource File

CRF • Lesson Plan• Directed Reading Ab• Directed Reading Bs

Technology

Transparencies• Bellringer• P3 Differences Between Mass and Weight• LINK TOLINK TO LIFE SCIENCELIFE SCIENCE L6 Math Focus: Surface

Area-to-Volume Ratio

Workbooks

Interactive Textbook Struggling Readers Struggling Readers


Volume � 15 mL

Liquid VolumeLake Erie, the smallest of the Great Lakes, has a volume of approximately 483 trillion (that’s 483,000,000,000,000) liters of water. Can you imag-ine that much water? Think of a 2-liter bottle of soda. The water in Lake Erie could fill more than 241 trillion 2-liter soda bottles. That’s a lot of water! On a smaller scale, a can of soda has a volume of only 355 milliliters, which is about one-third of a liter. You can check the volume of the soda by using a large meas uring cup from your kitchen.

Liters (L) and milliliters (mL) are the units used most often to express the volume of liquids. The volume of any amount of liquid, from one raindrop to a can of soda to an entire ocean, can be expressed in these units.

✓Reading Check What are two units used to meas urevolume? (See the Appendix for answers to Reading Checks.)

Measuring the Volume of Liquids In your science class, you’ll probably use a graduated cylinder instead of a measuring cup to measure the volume of liquids. Graduated cylinders are used to measure the liquid volume when accuracy is impor-tant. The surface of a liquid in any container, includ-ing a measuring cup or a large beaker, is curved. The curve at the surface of a liquid is called a meniscus(muh NIS kuhs). To measure the volume of most liquids, such as water, you must look at the bottom of the meniscus, as shown in Figure 2. Note that you may not be able to see a meniscus in a large beaker. The meniscus looks flat because the liquid is in a wide container.

Figure 2 To measure volume correctly, read the scale of the lowest part of the meniscus (as shown) at eye level.

meniscus the curve at a liquid’s sur-face by which one measures the volume of the liquid

Space Case1. Crumple a piece of paper. Fit it tightly in the

bottom of a clear plastic cup so that it won’t fall out.

2. Turn the cup upside down. Lower the cup straight down into a bucket half-filled with water. Be sure that the cup is completelyunderwater.

3. Lift the cup straight out of the water. Turn the cup upright, and observe the paper. Record your observations.

4. Use the point of a pencil to punch a small hole in the bottom of the cup. Repeat steps 2 and 3.

5. How do the results show that air has volume? Explain your answer.

GroupGroup vv -------g

Provide small groups with a variety of jars, bottles, cans, and cartons. Allow students to use a measuring cup or a graduated cyl-inder to determine the volume of each container. A volume reading is always made at the flattest part of the meniscus—the bottom of the curve for water and the top for mercury. l Visual/Interpersonal

Discussion ----------------------------------g

Discuss with students the fact that we are surrounded by matter. Have students give examples of matter around them. Ask them to list some characteristics of matter. Discuss with them that air is mat-ter and they are actually pushing air aside as they walk through it. l Logical

M A T E R I A L SFOR EACH STUDENT

• cup• piece of paperFOR EACH GROUP

• beaker or bucket, large• pencil• water

Teacher’s Notes: Students can feel the air being “moved out of the way” by the water if they hold a finger above the hole while they submerge the cup.

Answers

5. The water could not enter the cup because air occu-pied the space. Once the hole was punched, the water could force the air out of the cup and occupy the space in the cup.

oDetermining Official Standards The offi-cial standard kilogram is a cylinder made of platinum-iridium alloy. The mass of the cylinder is supposed to equal the mass of 1 dL3 of pure water at 4°C. Some scientists believe that this cylinder is imprecise and needs to be changed. In fact, the kilogram is the only SI unit that is based on a single physical standard and that can be destroyed or altered. Some scientists now suggest rede-fining the kilogram as the mass of an exact number of atoms of a particular element.

Answer to Reading Check

liters (L) and milliliters (mL)

Section 1 • What Is Matter? 39

1m

1 m

� �

� �� 1 m

Volume of a Regularly Shaped Solid Object The volume of any solid object is expressed in cubic units. The word cubic means “having three dimensions.” In sci-ence, cubic meters (m3) and cubic centimeters (cm3) are the units most often used to express the volume of solid things. The 3 in these unit symbols shows that three quantities, or dimensions, were multiplied to get the final result. You can see the three dimensions of a cubic meter in Figure 3.There are formulas to find the volume of regularly shaped objects. For example, to find the volume of a cube or a rectangular object, multiply the length, width, and height of the object, as shown in the following equation:

Volume of an Irregularly Shaped Solid ObjectHow do you find the volume of a solid that does not have a regular shape? For example, to find the volume of a 12-sided object, you cannot use the equation given above. But you can measure the volume of a solid object by measuring the volume of water that the object displaces. In Figure 4,when a 12-sided object is added to the water in a graduated cylinder, the water level rises. The volume of water displaced by the object is equal to its volume. Because 1 mL is equal to 1 cm3, you can express the volume of the water displaced by the object in cubic centimeters. Although volumes of liquids can be expressed in cubic units, volumes of solids should not be expressed in liters or milliliters.

✓Reading Check Explain how you would measure the vol-ume of an apple.

Volume of a Rectangular Solid What is the volume of a box that has a length of 5 cm, a width of 1 cm, and a height of 2 cm?

Step 1: Write the equation for volume.

volume � length � width � height

Step 2: Replace the variables with the measure-ments given to you, and solve.

volume � 5 cm � 1 cm � 2 cm � 10 cm3

Figure 4 The 12-sided object displaced 15 mL of water. Because 1 mL � 1 cm3, the volume of the object is 15 cm3.

Figure 3 A cubic meter (1 m3) is a cube that has a length, width, and height of 1 m.

Now It’s Your Turn1. A book has a length of 25 cm,

a width of 18 cm, and a height of 4 cm. What is its volume?

2. What is the volume of a suit-case that has a length of 95 cm, a width of 50 cm, and a height of 20 cm?

3. A CD case is 14.2 cm long, 12.4 cm wide, and 1 cm deep. What is its volume?

volume � length � width � height

CONNECTIONCONNECTION vvMath ----------------------------------------------------------------------------g

A “Refreshing” Statistic In 1997, Americans consumed an average of 204 L of soft drinks per person. How many cans of soft drinks would that be? Assume that a can holds 355 mL and remember that 1 L �1,000 mL. (more than 574 cans)

The total volume of soft drinks consumed by Americans in 1997 was approximately 53 billion liters. How many cans of soft drinks would that be? (more than 149 billion cans) l Logical

Answers to Math Focus

1. 1,800 cm3

2. 95,000 cm3, or 0.095 m3

3. 176.08 cm3

Demonstration --------------g

Relating Matter, Mass, and Volume Display a variety of classroom objects, such as pen-cils, books, and notebook paper. Ask students which objects con-tain the largest amount of matter and thus have the greatest mass. Then, ask which objects contain the smallest amount of matter and thus have the smallest mass. Ask them if the objects that have the greatest volume always have the most mass. l Visual/Logical ee


You could measure the volume of an apple by submerging it in a container of water and measuring the volume of the water that the apple displaces.

Mauna Loa, in Hawaii, is the world’s most active volcano. The volume of lava that has flowed from the volcano is enough to pave a four-lane highway that reaches around the world 30 times.


Matter and MassAnother characteristic of all matter is mass. Mass is the amountof matter in an object. For example, you and a peanut are madeof matter. But you are made of more matter than a peanut is,so you have more mass. The mass of an object is the same nomatter where in the universe the object is located. The onlyway to change the mass of an object is to change the amountof matter that makes up the object.

The Difference Between Mass and WeightThe terms mass and weight are often used as though theymean the same thing, but they don’t. Weight is a measure ofthe gravitational (GRAV i TAY shuh nuhl) force exerted on anobject. Gravitational force keeps objects on Earth from floatinginto space. The gravitational force between an object and theEarth depends partly on the object’s mass. The more mass anobject has, the greater the gravitational force on the objectand the greater the object’s weight. But an object’s weight canchange depending on its location in the universe. An objectwould weigh less on the moon than it does on Earth becausethe moon has less gravitational force than Earth does. Figure 5explains the differences between mass and weight.

mass a measure of the amount ofmatter in an object

weight a measure of the gravita-tional force exerted on an object; itsvalue can change with the location ofthe object in the universe

Differences Between Mass and WeightFigure 5

Mass

• Mass is a measure of the amountof matter in an object.

• Mass is always constant for anobject no matter where the objectis located in the universe.

• Mass is measured by using abalance (shown below).

• Mass is expressed in kilograms (kg),grams (g), and milligrams (mg).

Weight

• Weight is a measure of thegravitational force on an object.

• Weight varies depending onwhere the object is in relationto the Earth (or any large bodyin the universe).

• Weight is measured by using aspring scale (shown at right).

• Weight is expressed innewtons (N).

CONNECTIONCONNECTION vvLife Science---------------------------------b

Why Cells Are MicroscopicUse the teaching transparency“Math Focus: Surface Area-to-Volume Ratio” to show studentsthat as an object of a particularshape increases in size, its vol-ume grows proportionately morethan its surface area does. In liv-ing cells, oxygen, nutrients, andwaste must pass through the cellmembrane at a rate sufficient forthe cell to carry out its func-tions. Most cells are microscopicin size and have a high surfacearea-to-volume ratio, so thecytoplasm in the cell is closeenough to the cell membranefor substances to enter and exitthe cell quickly. Remind stu-dents that because cells requirea large surface-area-to-volumeratio, larger organisms do notgenerally have larger cells; theyhave more cells than smallerorganisms. l Visual/Logical

StrategiesStrategiesINCLUSIONINCLUSION

• Developmentally Delayed• Attention Deficit Disorder• Hearing ImpairmentGive students a chance tomove around while theyexplore the idea “lighter thanair.” Begin with two like-sizedballoons. Fill one with helium.Blow the other up with air tothe same size as the helium-filled balloon. Choose twostudents who especially needopportunities to move aroundduring class. Hand the balloonsto the students, ask them to letgo of the balloons on the countof three, and then count tothree for them. As the balloonfilled with air sinks to the floorand the helium balloon rises tothe ceiling, discuss that heliumis lighter than air. l Kinesthetic

MISCONCEPTIONALERT

Varying Volume of Gas Students maynot understand that a gas not only canexpand to fill its container but also canbe compressed, or squeezed, to fill asmaller container. Scuba divers’ tankscontain compressed air. A 2.24 m3 scubatank holds enough air for an averageadult to breathe underwater for 30to 45 min.

SUPPORT FOR

English Language LearnersWeight Students may have trouble un-derstanding this word unless they havehad previous exposure to the scientificmeaning of weight. To illustrate weightvariability, ask pairs of students to use aspring scale to weigh a slice of bread anda shoe and note their weights. Then,point out that Mars has 38 percent ofEarth’s gravity, so objects on Mars wouldweigh only 38 percent of what they doon Earth. Have students calculate theweight of the bread and the shoe onMars.l Verbal/Logical Section 1 • What Is Matter? 41

Measuring Mass and WeightThe brick and the sponge in Figure 6 have the same vol-ume. But because the brick has more mass, a greater gravi-tational force is exerted on the brick than on the sponge. As a result, the brick weighs more than the sponge.

The SI unit of mass is the kilogram (kg), but mass is often expressed in grams (g) and milligrams (mg), too. These units can be used to express the mass of any object in the universe.

Weight is a measure of gravitational force and is expressed in the SI unit of force, the newton (N). One newton is about equal to the weight of an object that has a mass of 100 g on Earth. So, if you know the mass of an object, you can calcu late the object’s weight on Earth. Weight is a good estimate of the mass of an object because, on Earth, gravity doesn’t change.

✓Reading Check

InertiaImagine kicking a soccer ball that has the mass of a bowling ball. It would be not only painful but also very difficult to get the ball moving in the first place! The reason is inertia (in UHR shuh). Inertia is the tendency of an object to resist a change in motion. So, an object at rest will remain at rest until something causes the object to move. Also, a moving object will keep moving at the same speed and in the same direction unless something acts on the object to change its speed or direction.

Figure 6 The brick and the sponge take up the same amount of space. But the brick has more matter in it, so its mass—and thus its weight—is greater.

inertia the tendency of an object to resist being moved or, if the object is moving, to resist a change in speed or direction until an outside force acts on the object

Converting Mass to Weight A student has a mass of 45,000 g. How much does this student weigh in newtons?

Step 1: Write the information given to you.

45,000 g

Step 2: Write the conversion factor to change grams into newtons.

1 N � 100 g

Step 3: Write the equation so that grams willcancel.

Now It’s Your Turn1. What is the weight of a car that has a

mass of 1,362,000 g?2. Your pair of boots has a mass of 850 g.

If each boot has exactly the same mass, what is the weight of each boot?

What units are often used to measure mass?

45,000 g �100 g

� 450 N1 N


1. 13,620 N2. 4.25 N


kilograms (kg), grams (g), and milligrams (mg)

Reteaching -------------------------------------bProvide students with graduated cylinders, spring scales, and tri-ple-beam balances. Have students take turns explaining step-by-step how to measure the volume and the mass of a given substance. Help them observe the difference between mass and weight using a spring scale. l Logical

Quiz ---------------------------------------------------------------------g

Ask students whether these questions are true or false.

1. The volume of a marble can be measured with a graduated cylinder. (true)

2. Volumes of solids can be expressed in liters or milliliters. (false)

3. Weight and mass are the same thing. (false)

Alternative Assessment ---------------------------g

PORTFOLIO

An Alternate UniverseHave students write a

short science-fiction story about a universe in which matter does not behave in the ways described in this section. Ask them to con-sider what life would be like in this kind of universe. Some exam-ples are a universe where gravity does not exist; a universe where objects repel rather than attract one another; and a universe where inertia becomes greater as mass decreases. l Visual


For a variety of links related to this chapter, go to www.scilinks.org

SummarySummary

Review

Topic: What Is Matter?SciLinks code: HSM1662

• Two properties of matter are volume and mass.

• Volume is the amount of space taken up by an object.

• The SI unit of volume is the liter (L).

• Mass is the amount of matter in an object.

• The SI unit of mass is the kilogram (kg).

• Weight is a measure of the gravitational force on an object, usually in rela-tion to the Earth.

• Inertia is the tendency of an object to resist being moved or, if the object is moving, to resist a change in speed or direction. The more massive an object is, the greater its inertia.

Using Key Terms

1. Use the following terms in the same sentence: volume andmeniscus.

2. In your own words, write a defi-nition for each of the following terms: mass, weight, and inertia.

Understanding Key Ideas

3. Which of the following ismatter?

a. dust c. strand of hairb. the moon d. All of the

above

4. A graduated cylinder is used to measure

a. volume. c. mass.b. weight. d. inertia.

5. The volume of a solid is meas-ured in

a. liters.b. grams.c. cubic centimeters.d. All of the above

6. Mass is measured in

a. liters. c. newtons.b. centimeters. d. kilograms.

7. Explain the relationship between mass and inertia.

Math Skills

8. A nugget of gold is placed in a graduated cylinder that contains 80 mL of water. The water level rises to 225 mL after the nugget is added to the cylinder. What is the volume of the gold nugget?

9. One newton equals about 100 g on Earth. How many newtons would a football weigh if it had a mass of 400 g?

Critical Thinking

10. Identifying Relationships Do objects with large masses always have large weights? Explain.

11. Applying Concepts Would an elephant weigh more or less on the moon than it would weigh on Earth? Explain your answer.

Mass: The Measure of InertiaMass is a measure of inertia. An object that has a large mass is harder to get moving and harder to stop than an object that has less mass. The reason is that the object with the large mass has greater inertia. For example, imagine that you are going to push a grocery cart that has only one potato in it. Pushing the cart is easy because the mass and inertia are small. But suppose the grocery cart is stacked with potatoes, as in Figure 7.Now the total mass—and the inertia—of the cart full of potatoes is much greater. It will be harder to get the cart moving. And once the cart is moving, stopping the cart will be harder.

Figure 7 Because of inertia, moving a cart full of potatoes is more difficult than moving a cart that is empty.

Answers to Section Review

1. Sample answer: You can measure the volume of a liquid by pouring it into a graduated cylinder and reading the scale at the bottom of the meniscus.

2. Sample answer: Mass is a measurement of how much matter is in an object. Weight is a measurement of how much gravitational force is exerted on an object’s mass. Inertia is what causes an object to remain at rest or remain in motion. The more mass an object has, the greater its inertia.

3. d4. a5. c6. d7. Mass is a measure of iner-

tia. The more mass an object has, the more inertia it has.

8. 145 cm3

9. 4 N10.Not all objects that have large

masses have large weights because the weight of an object can change depending on where it is located in the universe. Mass remains the same everywhere in the uni-verse. So, a massive object in space may not have a large weight.

11.The elephant’s weight on the moon would be only one-sixth of its weight on Earth. This dif-ference is due to the moon having only one-sixth the gravi-tational force of the Earth.

CHAPTER RESOURCES


• Section Quiz g• Section Review g• Vocabulary and Section Summary g• SciLinks Activity g• Datasheet for Quick Lab

CRF

Section 1 • What Is Matter? 43

READING STRATEGY

Physical PropertiesHave you ever played the game 20 Questions? The goal of thisgame is to fi gure out what object another person is thinking ofby asking 20 yes/no questions or less.

If you can’t figure out the object’s identity after asking 20questions, you may not be asking the right kinds of questions.What kinds of questions should you ask? You may want to askquestions about the physical properties of the object. Knowingthe properties of an object can help you find out what it is.

Physical PropertiesThe questions in Figure 1 help someone gather informationabout color, odor, mass, and volume. Each piece of informationis a physical property of matter. A physical propertyphysical property of mattercan be observed or measured without changing the matter’sidentity. For example, you don’t have to change an apple’sidentity to see its color or to measure its volume.

Other physical properties, such as magnetism, the abilityto conduct electric current, strength, and flexibility, can helpsomeone identify how to use a substance. For example, thinkof a scooter with an electric motor. The magnetism producedby the motor is used to convert energy stored in a batteryinto energy that will turn the wheels.

✓✓Reading Check List four physical properties. (See the Appendix foranswers to Reading Checks.)

2

Figure 1 Askingquestions about thephysical properties ofan object can help youidentify it.

What You Will Learn

Identify six examples of physicalproperties of matter.Describe how density is used toidentify substances.List six examples of physical changes.Explain what happens to matterduring a physical change.

Vocabularyphysical propertydensityphysical change

Mnemonics As you read this section,create a mnemonic device to helpyou remember examples of physicalproperties.

Could I hold it in my hand? Yes.Does it have an odor? Yes.Is it safe to eat? Yes.Is it orange? No.Is it yellow? No.Is it red? Yes.Is it an apple? Yes!

2

OverviewThis section introduces studentsto the physical properties ofmatter. It also explains how den-sity is used to identify differentsubstances. The section con-cludes with an explanation ofwhat happens to matter duringphysical changes.

BellringerHave your students writean answer to the followingquestion, “If you were asked todescribe an orange to someonewho had never seen an orange,what would you tell the person?”Then, have volunteers presenttheir answers to the class.

Demonstration --------------gAn Accurate Description Dis-play several objects that havedifferences in color, odor, tex-ture, size, shape, and state. Allowstudents to examine the objects.Then, ask them to describe eachobject in terms of its color, odor,texture, size, shape, and state.Ask students why it is importantto use a variety of propertieswhen describing objects.l Visual/Kinesthetic


Some physical properties are color, shape, odor,weight, volume, texture, state, and density.

CHAPTER RESOURCES


CRF • Lesson Plan• Directed Reading Ab• Directed Reading Bs

Technology

Transparencies• Bellringer

Workbooks



mass � 46 g

mass � 2 g

Thermal conduc-tivity (KAHN duhkTIV uh tee) is therate at which asubstancetransfers heat.Plastic foam is apoor conductor.

Identifying MatterYou use physical properties every day. For example, physicalproperties help you determine if your socks are clean (odor),if your books will fit into your backpack (volume), or if yourshirt matches your pants (color). Figure 2 gives more examplesof physical properties.

DensityDensity is a physical property that describes the relationshipbetween mass and volume. Density is the amount of matter ina given space, or volume. A golf ball and a table-tennis ball,such as those in Figure 3, have similar volumes. But a golf ballhas more mass than a table-tennis ball does. So, the golf ballhas a greater density.

physical property a characteristicof a substance that does not involvea chemical change, such as density,color, or hardness

density the ratio of the massof a substance to the volume ofthe substance

Figure 2 Examples of Physical Properties

Figure 3 A golf ball is denserthan a table-tennis ball becausethe golf ball contains morematter in a similar volume.

Solubility (SAHL

yoo BIL uh tee)is the ability ofa substance todissolve inanother substance.Flavored drink mixdissolves in water.

Ductility(duhk TILuh tee) is

the ability of a substanceto be pulled into a wire.Copper is often used tomake wiring because it isductile.

State is thephysical formin which a sub-stance exists,such as a solid,liquid, or gas.Ice is water inthe solid state.

Density is themass per unitvolume of asubstance. Lead isvery dense, soit makes a goodsinker for afishing line.

Malleability(MAL ee uh BILuh tee) is theability of a substance to berolled or pounded into thin sheets.Aluminum can be rolled into sheetsto make foil.

Discussion ----------------------------------gPhysical Properties Draw stu-dents’ attention to the examplesof physical properties shown inFigure 2. After reading throughthe definition and example ofeach property, ask volunteers togive another example of thesame property. l Visual

CONNECTION toCONNECTION toReal World -----------------------------------g

No Wooden Nickels! Electroniccoin testers in vending machinescan instantly identify the prop-erties of real coins and rejectfake coins. First, an electric cur-rent passes through the coin tomeasure its metal content andsize. Only real coins conduct theright amount of electricity. Next,a magnet and light sensors areused to detect the coin’s sizeand sort coins according to theirvalue. Coins that do not havethe correct metal content or arenot the correct size are rejected.

h-----------------------------g

Writing Guessing Game Havestudents write a descrip-tion of the properties of

a favorite object from home,such as a bicycle, a pet, a typeof food, or an article of clothing.Let students read their descriptionaloud, and have other class mem-bers try to guess the object beingdescribed. l Visual/Interpersonal

SUPPORT FOR

English Language LearnersPhysical Properties Students may beable to understand the vocabulary in thechart of examples of physical properties,but still may need additional examplesto help them grasp the concepts. Readthrough each property in the chart, mod-eling correct pronunciation as studentsread silently. After each property, dem-onstrate an additional example, pointingout the similarities between the demon-strated example and the text. Suggested

visuals include hot water inside a ceramicmug for thermal conductivity, pictures ofvarious of states of iron for state, a leadweight for density, sugar in iced tea forsolubility, a gold chain for ductility, andchocolate for malleability. As you demon-strate or show the visuals, call on studentsto define orally the physical propertybeing demonstrated in their own words.l Verbal/Visual

Section 2 • Physical Properties 45

Liquid LayersWhat do you think causes the liquid in Figure 4 to look the way it does? Is it trick photography? No, it is differences in density! There are six liquids in the graduated cylinder. Each liquid has a different density. If the liquids are carefully poured into the cylinder, they can form six layers because of the differences in density. The densest layer is on the bottom. The least dense layer is on top. The order of the layers shows the order of increasing density. Yellow is the least dense, followed by the colorless layer, red, blue, green, and brown (the densest).

Density of SolidsWhich would you rather carry around all day: a kilogram of lead or a kilogram of feathers? At first, you might sayfeathers. But both the feathers and the lead have the same mass, just as the cotton balls and the tomatoes have the same mass, as shown in Figure 5. So, the lead would be less awkward to carry around than the feathers would. The feathers are much less dense than the lead. So, it takes a lot of feathers to equal the same mass of lead.

Knowing the density of a substance can also tell you if the substance will float or sink in water. If the density of an object is less than the density of water, the object will float. Likewise, a solid object whose density is greater than the density of water will sink when the object is placed in water.

✓Reading Check What will happen to an object placed in water if the object’s density is less than water’s density?

Figure 4 This graduated cylinder contains six liquids. From top to bottom, they are corn oil, water, shampoo, dish detergent, antifreeze, and maple syrup.

Figure 5 The cotton balls and the tomatoes have the same mass. But cotton is much less dense than the tomatoes.

CONNECTIONCONNECTION vvMath -----------------------------------------------------------g

Density Calculations Ask stu-dents to use the equation for density to solve the following problems.

1. A block of pine wood has a mass of 120 g and a volume of 300 cm3. What is the den-sity of the wood? (0.4 g/cm3)Will this block of pine float in a pool of water? Why or why not? (It will float because it is less dense than water.)

2. A sample of metal has a mass of 3,623 g and a volume of 508 cm3. What metal is it? (zinc)

l Logical

MISCONCEPTIONALERT

Changes in DensityStudents may think that the density of a substance remains constant as tempera-ture and pressure change. Remind students that densi-ties such as those listed in the table on the following page are valid only at the given temperature and pres-sure. As the temperature and pressure conditions change, the density will also change.


If the object’s density is less than the water’s density, the object will float.

There was a period of time in history when a person who was suspected of being a witch was tossed into a lake. It was believed that a witch would float, while a person who was not a witch would sink.


D �mV

V � (Rearrange by dividing by D.)mD

m � D � V (Rearrange by multiplying by V.)

D �mV

D � � 2.5 g/cm25 g

10 cm33

Solving for DensityTo find an object’s density (D), first measure its mass (m) andvolume (V). Then, use the equation below.

Units for density consist of a mass unit divided by a vol-ume unit. Some units for density are g/cm3, g/mL, kg/m3, andkg/L. Remember that the volume of a solid is often given incubic centimeters or cubic meters. So, the density of a solidshould be given in units of g/cm3 or kg/m3.

Using Density to Identify SubstancesDensity is a useful physical property for identifying substances.Each substance has a density that differs from the densities ofother substances. And the density of a substance is always thesame at a given temperature and pressure. Look at Table 1 tocompare the densities of several common substances.

Calculating Density What is the density of anobject whose mass is 25 g and whose volumeis 10 cm3?

Step 1: Write the equation for density.

Step 2: Replace m and V with the measurementsgiven in the problem, and solve.

The equation for density can also be re-arranged to find mass and volume, as shown.

Twenty QuestionsPlay a game of 20 Questionswith an adult. One personwill think of an object, andthe other person will askyes/no questions about it.Write the questions in yourscience journal as you play.Put a check mark next tothe questions asked aboutphysical properties. When theobject is identified or whenthe 20 questions are up,switch roles.

Now It’s Your Turn1. Find the density of a substance that

has a mass of 45 kg and a volume of43 m3. (Hint: Make sure your answer’sunits are units of density.)

2. Suppose you have a lead ball whosemass is 454 g. What is the ball’s vol-ume? (Hint: Use Table 1 above.)

3. What is the mass of a 15 mL sampleof mercury?

Table 1 Densities of Common Substances*Substance Density* (g/cm3) Substance Density* (g/cm3)

Helium (gas) 0.0001663 Zinc (solid) 7.13

Oxygen (gas) 0.001331 Silver (solid) 10.50

Water (liquid) 1.00 Lead (solid) 11.35

Pyrite (solid) 5.02 Mercury(liquid)

13.55

*at 20°C and 1.0 atm

vv--------------------------------------------------------b

Densities of Vinegar and OilVisual learners and students whohave limited English proficiencymay benefit from handlingsealed bottles of oil and vinegarto observe how the immiscibleoil and vinegar form layers ofdifferent densities.l Visual ee

MISCONCEPTIONALERT

Miscible or Immiscible?Factors unrelated to density determine whether liquidsare miscible or will dissolvein each other. Liquids of dif-ferent densities may be misci-ble, which means that liquidlayers will not form. Forexample, ethyl alcohol andwater have different densi-ties, but they dissolve in eachother. Conversely, liquids ofidentical density may beimmiscible, so liquid layerswill form. However, becausethe density of one substanceis usually different from thatof another, layering liquids isa useful way to compare therelative densities of immisci-ble liquids.


1. D � m/V, so D � 45 kg/43 m3 �1.05 kg/m3.

2. V � m/D, so V � 454g/11.35g/cm3 � 40 cm3.(Students must use the density of lead fromthe table on this page.)

3. m � D � V, so m � 13.55 g/mL � 15 mL �203 g. (Students must use the density of mer-cury from the table on this page.)

Is That a Fact!The density of a fresh egg is about1.2 g/mL, and the density of a spoiledegg is about 0.9 g/mL. The density ofthe egg decreases as it ages because as itspoils, it loses water through the tinypores in the shell. So, don’t eat an eggthat floats. It’s spoiled!


Physical Changes Do Not Form New SubstancesA physical change is a change that affects one or more physi-cal properties of a substance. Imagine that a piece of silver ispounded and molded into a heart-shaped pendant. This changeis a physical one because only the shape of the silver haschanged. The piece of silver is still silver. Its properties are thesame. Figure 6 shows more examples of physical changes.

✓Reading Check What is a physical change?

Examples of Physical ChangesFreezing water to make ice cubes and sanding a piece of woodare examples of physical changes. These changes do not changethe identities of the substances. Ice is still water. And sawdustis still wood. Another interesting physical change takes placewhen certain substances dissolve in other substances. Forexample, when you dissolve sugar in water, the sugar seemsto disappear. But if you heat the mixture, the water evaporates.Then, you will see that the sugar is still there. The sugar wentthrough a physical change when it dissolved.

Changing from a solid

Figure 6 Examples of Physical Changes

physical change a change of mat-ter from one form to another withouta change in chemical properties

WRITINGSKILL

Erosion Erosion of soil is a physical change. Soilerodes when wind and water move soil from one place

to another. Research the history of the Grand Canyon. Write a one-page report about how erosion formed the Grand Canyon.

This aluminum canhas gone through thephysical change of beingcrushed. The propertiesof the can are the same.

to a liquid is a physi-cal change. All changesof state are physicalchanges.

Reteaching -------------------------------------bDivide students into groups.Give each group a banana, alump of clay, and a sheet ofpaper. Ask groups to brainstormways to change the physicalproperties of each object. Havestudents demonstrate thechanges within their group.Emphasize that each objectremains the same substanceafter a physical change.l Logical

Quiz ---------------------------------------------------------------------g

1. List three physical propertiesof water. (colorless; liquid atroom temperature; density of1.00 g/mL; odorless; melting pointof 0°C; boiling point of 100°C; candissolve table salt and sugar)

2. You have two objects, bothabout the size of an orange.Object A has a mass of 1,487 g,and object B has a mass of878 g. Which object has thegreater density? Explain.(object A; Both objects havethe same volume, so the objectwith more mass has the greaterdensity.)

AlternativeAssessment ---------------------------g

Sugar Cube Activity Give eachstudent a sugar cube to examine.Have them write the physicalproperties they observe. Then,have them write three thingsthey could do to the sugar cubeto cause it to undergo a physicalchange. l Visual

Team 3: brick, box, sponge, and pieceof 2 � 4 wood board

Team 4: ping-pong ball, fishing weight,piece of charcoal, and small balloon withair in it

Ask teams to arrange the items in theirset in order of density, from most denseto least dense. Then, have each teamdemonstrate their arrangement to theclass and explain why they chose theorder they did. l Kinesthetic/Interpersonal

StrategiesStrategiesINCLUSIONINCLUSION

• Visually Impaired• Developmentally Delayed• Hearing ImpairedDivide the class into four teams. Giveeach team one of the sets of items listedbelow. Within each team, try to keep thefour items similar in size.

Team 1: potato, softball, ball of crum-pled aluminum foil, and ball of string

Team 2: softball, styrofoam ball, grape-fruit, and croquet or bocce ball


For a variety of links related to thischapter, go to www.scilinks.org

SummarySummary

Review

Matter and Physical ChangesPhysical changes do not change the identity ofthe matter involved. A stick of butter can bemelted and poured over a bowl of popcorn, asshown in Figure 7. Although the shape of thebutter has changed, the butter is still butter, soa physical change has occurred. In the same way,if you make a figure from a lump of clay, youchange the clay’s shape and cause a physicalchange. But the identity of the clay does notchange. The properties of the figure are the sameas those of the lump of clay.

Figure 7 Meltingbutter for popcorninvolves a physicalchange.

• Physical properties ofmatter can be observedwithout changing theidentity of the matter.

• Examples of physicalproperties are conduc-tivity, state, malleability,ductility, solubility, anddensity.

• Density is the amount ofmatter in a given space.

• Density is used to iden-tify substances becausethe density of a sub-stance is always thesame at a given pressureand temperature.

• When a substanceundergoes a physicalchange, its identity staysthe same.

• Examples of physicalchanges are freezing,cutting, bending, dissolv-ing, and melting.

Using Key Terms

1. Use each of the following termsin a separate sentence: physicalproperty and physical change.


2. The units of density for a rectan-gular piece of wood are

a. grams per milliliter.b. cubic centimeters.c. kilograms per liter.d. grams per cubic centimeter.

3. Explain why a golf ball isheavier than a table-tennis balleven though the balls are thesame size.

4. Describe what happens to a sub-stance when it goes through aphysical change.

5. Identify six examples of physicalproperties.

6. List six physical changes thatmatter can go through.

Math Skills

7. What is the density of an objectthat has a mass of 350 g and avolume of 95 cm3? Would thisobject float in water? Explain.

8. The density of an object is5 g/cm3, and the volume of theobject is 10 cm3. What is themass of the object?

Critical Thinking

9. Applying Concepts How canyou determine that a coin is notpure silver if you know the massand volume of the coin?

10. Identifying RelationshipsWhat physical property do thefollowing substances have incommon: water, oil, mercury,and alcohol?

11. Analyzing Processes Explainhow you would find the densityof an unknown liquid if youhave all of the laboratory equip-ment that you need.

Topic: Describing Matter; Physical ChangesSciLinks code: HSM0391; HSM1142


1. Sample answer: A physicalproperty can be observed with-out changing the identity of thematter. When matter undergoesa physical change, its shape orform changes, but its identityremains the same.

2. d3. A golf ball feels heavier

than a table-tennis ball becausea golf ball is denser; that is, ithas more mass in a similar volume.

4. A physical change changesthe shape or form of the matterwithout changing its identity. Itis still the same matter asbefore the change and hassome of the same properties.

5. Some physical propertiesinclude color, shape, odor, vol-ume, weight, and density.

6. Some physical changesthat matter can go through arebreaking, melting, freezing, cut-ting, crushing, and dissolving.

7. 3.68 g/cm3 This objectwould not float in waterbecause its density is greaterthan the density of water.

8. 50 g9. Use the mass and volume

of the coin to calculate thecoin’s density. Compare thisdensity with the known densityof silver.

10.They are liquids.11. Sample answer: I would find

the mass of a clean, dry gradu-ated cylinder, pour some of theunknown liquid into the gradu-ated cylinder, and note the vol-ume. Then, I would find themass of the graduated cylinderwith the liquid in it. Next, Iwould subtract the mass of theempty graduated cylinder fromthe mass of the graduated cyl-inder with the liquid in it to findthe mass of the liquid. Finally, Iwould divide the mass of theliquid by the volume of the liq-uid to calculate the density.


A physical change is a change that occurs to asubstance or object and that does not changethe identity of the substance.

CHAPTER RESOURCES


• Section Quizg • Section Reviewg • Vocabulary and Section Summaryg • Reinforcement Worksheetb

CRF


READING STRATEGY

Chemical PropertiesHow would you describe a piece of wood before and after it is burned? Has it changed color? Does it have the same texture? The original piece of wood changed, and physical properties alone can’t describe what happened to it.

Chemical PropertiesPhysical properties are not the only properties that describematter. Chemical propertiesChemical properties describe matter based on its abilityto change into new matter that has different properties. Forexample, when wood is burned, ash and smoke are created.These new substances have very different properties than theoriginal piece of wood had. Wood has the chemical propertyof flammability. Flammability is the ability of a substance toburn. Ash and smoke cannot burn, so they have the chemicalproperty of nonflammability.

Another chemical property is reactivity. Reactivity is theability of two or more substances to combine and form oneor more new substances. The photo of the old car in Figure 1illustrates reactivity and nonreactivity.

✓✓Reading Check What does the term reactivity mean? (See the Appendix for answers to Reading Checks.)

3

chemical propertychemical property a prop-erty of matter that describes a substance’s ability to participate in chemical reactions

Reactivity with OxygenFigure 1

The bumper on this car still looks new because it is coated with chromium. Chromium has the chemi-cal property of nonreac-tivity with oxygen.

The iron used in this old car has the chemi-cal property of reactivity with oxygen. When iron is exposed to oxygen, it rusts.

What You Will Learn

Describe two examples of chemicalproperties.Explain what happens during achemi cal change.Distinguish between physical andchemical changes.

Vocabularychemical propertychemical change

Reading Organizer As you read thissection, create an outline of the sec-tion. Use the headings from the sec-tion in your outline.

OverviewIn this section, students willlearn about the chemical proper-ties of matter and how chemicalproperties differ from physicalproperties. They will also learnthat when chemical changesoccur to matter, new substancesare formed.

BellringerHave students look at the pictureof the car in Figure 1. Then, havethem describe where they haveseen other examples of rusting.Have volunteers share their des-criptions aloud with the class.

Demonstration --------------gPhysical and Chemical ChangesShow students a match, a can-dle, and a stick. Ask them whatphysical changes can be made toeach item. Light the match, andmelt some of the candle wax.Ask students if the melting waxis a physical or chemical change.Light the candle wick, and pointout that the candle wax and thewick are burning and undergo-ing a chemical change. The waxand the wick do not remain thesame substances they werebefore they were burned.l Visual/Logical


Reactivity describes the ability of two ormore substances to combine and form oneor more new substances.

3

CHAPTER RESOURCES


CRF • Lesson Plan • Directed Reading Ab • Directed Reading Bs

Technology

Transparencies• Bellringer• P4 Examples of Chemical Changes

Workbooks



Physical property Chemical property

SKILL

Comparing Physical and Chemical PropertiesHow do you tell a physical property from a chemical property? You can observe physical properties without changing the identity of the substance. For example, you can find the density and hardness of wood without changing anything about the wood.

Chemical properties, however, aren’t as easy to observe. For example, you can see that wood is flammable only while it is burning. And you can observe that gold is nonflammable only when it won’t burn. But a substance always has chemical properties. A piece of wood is flammable even when it’s not burning. Figure 2 shows examples of physical and chemical properties.

Characteristic PropertiesThe properties that are most useful in identifying a substance are characteristic properties. These properties are always the same no matter what size the sample is. Characteristic properties can be physical properties, such as density and solubility, as well as chemical properties, such as flammability and reactiv-ity. Scientists rely on characteristic properties to identify and classify substances.

Shape Bending an iron nail will change its shape.

State Rubbing alcohol is a clear liquid at room temperature.

Reactivity with OxygenAn iron nail can react with oxygen in the air to form iron oxide, or rust.

Physical Versus Chemical PropertiesFigure 2

Flammability Rubbing alcohol is able to burn easily.

The Right StuffWhen choosing

materials to use in manufac-turing, you must make sure their properties are suitable for their uses. For example, false teeth can be made from acrylic plastic, porcelain, or gold. According to legend, George Washington wore false teeth made of wood. Do research and find what Washington’s false teeth were really made of. In your science journal,write a paragraph about what you have learned. Include information about the advan-tages of the materials used in modern false teeth.

READINGSTRATEGY -------------------g

Prediction Guide Before stu-dents read this page, ask them, “What are some useful chemical properties of iron?” (its high melt-ing point, its nonreactivity with oil and gasoline, its nonflammability)l Logical

CONNECTIONCONNECTION vvLife Science ----------------------------g

Water’s Importance to Life The chemical properties of water make it an essential molecule for life. Water can dissolve many substances in our bodies that are needed for the functioning of cells. Water is also important to plants as a reactant in photo-synthesis. Have students use the library or Internet resources to learn more about the importance of water to living things. Have them write a research paper or make a poster that illustrates their findings. l Logical

CONNECTION toCONNECTION to Real World -----------------------------------g

Rustproofing Rustproofing is one way to help protect cars from rust. The process involves treating the car’s underside and panels—such as the doors, the trunk, and the hood—with sealants. The sealants pen-etrate all the seams, cracks, and holes to keep out air and moisture, which can increase the rate at which rust forms.

Is That a Fact!Galvanized steel is steel that is coated with zinc to prevent rusting. It is used in buckets and nails. And steel plated with tin was used in food cans and con-tainers. Today, aluminum cans have replaced most steel cans.

Section 3 • Chemical Properties 51

The hot gas formed when hydrogen and oxygen join to make water helps blast the space shuttle into orbit.

Chemical Changes and New Substances A chemical change happens when one or more substances are changed into new substances that have new and different properties. Chemical changes and chemical properties are not the same. Chemical properties of a substance describe which chemical changes will occur and which chemical changes will not occur. But chemical changes are the process by which substances actually change into new substances. You can learn about the chemical properties of a substance by looking at the chemical changes that take place.

You see chemical changes more often than you may think. For example, a chemical reaction happens every time a battery is used. Chemicals failing to react results in a dead battery. Chemical changes also take place within your body when the food you eat is digested. Figure 3 describes other examples of chemical changes.

✓Reading Check How does a chemical change differ from a chemical property?

Soured milk smells bad because bacteria have formed new substances in the milk.

Examples of Chemical ChangesFigure 3

Changing Change1. Place a folded paper

towel in a small pieplate.

2. Pour vinegar into the pie plate until the entire paper towel is damp.

3. Place three shiny pennieson top of the paper towel.

4. Put the pie plate in a safe place. Wait 24 hours.

5. Describe and explain the change that took place.

The Statue of Liberty is made of orange-brown copper but it looks green from the metal’s interaction with moist air. New copper compounds formed and these chemical changes made the statue turn green over time.

Effervescent tabletsbubble when the citric acid and baking soda in them react in water.

M A T E R I A L SFOR EACH GROUP

• paper towel• pennies, shiny (2 or 3)• pie plate• vinegar

Safety Caution: Have stu-dents wear goggles, gloves, and an apron for this activity.

Answer

5. The shiny copper surface became coated with a dull, green substance. The color change and change in the appearance of the coin indi-cated that a chemical change took place.


Chemical changes occur when one or more substances are changed into entirely new sub-stances with different properties. A chemical property of a substance determines whether a chemical change will occur.


What Happens During a Chemical Change?A fun way to see what happens during chemical changes is tobake a cake. You combine eggs, flour, sugar, and other ingre-dients, as shown in Figure 4. When you bake the batter, youend up with something completely different. The heat of theoven and the interaction of the ingredients cause a chemicalchange. The result is a cake that has properties that differ fromthe properties of the ingredients.

Signs of Chemical ChangesLook back at Figure 3. In each picture, at least one sign indicatesa chemical change. Other signs that indicate a chemical changeinclude a change in color or odor, production of heat, fizzingand foaming, and sound or light being given off.

In the cake example, you would smell the cake as it baked.You would also see the batter rise and begin to brown. Whenyou cut the finished cake, you would see the air pockets madeby gas bubbles that formed in the batter. These signs showthat chemical changes have happened.

Matter and Chemical ChangesChemical changes change the identity of the matter involved.So, most of the chemical changes that occur in your dailylife, such as a cake baking, would be hard to reverse. Imaginetrying to unbake a cake. However, some chemical changescan be reversed by more chemical changes. For example, thewater formed in the space shuttle’s rockets could be split intohydrogen and oxygen by using an electric current.

chemical change a change thatoccurs when one or more substanceschange into entirely new substanceswith different properties

Figure 4 Each of theoriginal ingredients hasdifferent physical andchemical properties than thefinal product, the cake, does!

For another activity relatedto this chapter, go togo.hrw.com and type in key-word HP5MATW.

vv--------------------------------------g

Observing a Chemical ChangeGive each student a self-sealingplastic bag, a small plastic pillbottle, a small amount of hydro-gen peroxide (3% solution), and asmall piece of clean steel wool.Tell students to wear safety gog-gles and an apron, and cautionthem to handle the hydrogen per-oxide carefully. Instruct studentsto fill the pill bottle halfway withhydrogen peroxide. Then, havethem place a small piece of steelwool and the pill bottle into theplastic bag, being careful not tospill the hydrogen peroxide. Tellthem to force the air out of thebag and seal it tightly. Then,instruct them to tip the bottleover so that the hydrogen perox-ide comes in contact with thesteel wool. Tell them to feel thebag and to observe what happens.Ask them how they know a chem-ical change has occurred. (A gasformed and inflated the bag; andthe bag was heated.)l Visual/Kinesthetic

vv--------------------------------------a

Expense of Desalination Havestudents explore why desalina-tion is so expensive. Then, havethem try to determine underwhat conditions it makes senseto use desalination on a largescale. (Desalination should be usedin places where the process is lessexpensive than piping or shippingfresh water from distant sources.)l Logical

SUPPORT FOR

English Language LearnersChemical Change To promote under-standing, point out to students thatphysical changes can be undone, butchemical changes cannot. The followingactivity will check comprehension of thedifference between chemical and physicalchange. Give each student a red index cardand a white index card. Tell them you aregoing to name some changes. When theyhear a physical change, they should raisethe red card; when they hear a chemical

change they should raise the white card.Read aloud the list of changes, pausing be-tween each to allow students to show theircards. When students have their cardsraised, affirm the answer and explain whythe change belongs in each category.• Fruit juice to frozen treat (physical)• Burning wood to ash (chemical)• Charcoal to diamonds (chemical)• Milk to butter (physical)l Logical


Physical Versus Chemical ChangesThe most important question to ask when trying to decide ifa physical or chemical change has happened is, Did the com-position change? The composition of an object is the type ofmatter that makes up the object and the way that the matteris arranged in the object. Figure 5 shows both a physical anda chemical change.

A Change in CompositionPhysical changes do not change the composition of a sub-stance. For example, water is made of two hydrogen atoms andone oxygen atom. Whether water is a solid, liquid, or gas, itscomposition is the same. But chemical changes do alter thecomposition of a substance. For example, through a processcalled electrolysis, water is broken down into hydrogen andoxygen gases. The composition of water has changed, so youknow that a chemical change has taken place.

Physical or Chemical Change?1. Watch as your teacher places a burning wooden stick into a

test tube. Record your observations.2. Place a mixture of powdered sulfur and iron filings on a

sheet of paper. Place a bar magnet underneath the paper,and try to separate the iron from the sulfur.

3. Drop an effervescent tablet into a beaker of water. Recordyour observations.

4. Identify whether each change is a physical change or a chemi-cal change. Explain your answers.

Change in TextureGrinding bakingsoda into a fine,powdery substanceis a physical change.

Reactivitywith VinegarGas bubblesare producedwhen vinegaris poured intobaking soda.

Physical and Chemical ChangesFigure 5

Acid Rain When fossil fuelsare burned, a chemical changetakes place. Sulfur from fos-sil fuels and oxygen from theair combine to produce sulfurdioxide, a gas. When sulfurdioxide enters the atmos-phere, it undergoes anotherchemical change by interact-ing with water and oxygen.Research this chemical reac-tion. Make a poster describingthe reaction and showing howthe final product affects theenvironment.

Reteaching -------------------------------------b

Chemical Changes Show stu-dents the following items: a rawegg that you have cracked openand placed in a beaker, a sheetof paper, and an iron nail. Askstudents to think of ways thatchemical changes could occur toeach item. Have them writedown the changes that theythink of, along with a descrip-tion of how the item is differentafter the change occurred.l Logical

Quiz ---------------------------------------------------------------------g

1. Give an example of a chemi-cal change that occurs duringthe preparation of a meal.(Sample answer: burning of gasin an oven or a stove burner)

2. List three clues that a chemi-cal change might be takingplace. (Possible answers includecolor change; bubbling and fizz-ing or foaming.)

AlternativeAssessment ---------------------------g

Another Sugar Cube ActivityGive each student a sugar cube.Have them write two thingsthey could do to the sugar cubeto cause it to undergo a chemi-cal change, and have them writethe chemical properties thesechanges represent. Studentsmay use their book to findexamples. l Visual

M A T E R I A L SFOR EACH GROUP

• effervescent tablet• magnet, bar• paper, sheet of plain white• sulfur and iron filings, mixture of powdered• water, beaker of

Safety Caution: Remind students towash their hands before leaving thelaboratory.

Answer

4. The burning wooden stick is undergoing achemical change because the wood is beingchanged into a new substance with differentproperties. Separating the iron filings and thepowdered sulfur is a physical change becausethe components of the mixture did not changeinto new substances. The effervescent tabletundergoes a chemical change when it isdropped in the water because it forms anew substance with different properties.


For a variety of links related to thischapter, go to www.scilinks.org

SummarySummary

Review

Figure 6 This display of fireworks representsmany chemical changes happening at thesame time.

• Chemical propertiesdescribe a substancebased on its ability tochange into a new sub-stance that has differentproperties.

• Chemical properties canbe observed only whena chemical change mighthappen.

• Examples of chemicalproperties are flamma-bility and reactivity.

• New substances formas a result of a chemicalchange.

• Unlike a chemicalchange, a physicalchange does notalter the identity ofa substance.

Using Key Terms

1. In your own words, write a defi-nition for each of the follow-ing terms: chemical property andchemical change.


2. Rusting is an example of a

a. physical property.b. physical change.c. chemical property.d. chemical change.

3. Which of the following is acharacteristic property?

a. densityb. chemical reactivityc. solubility in waterd. All of the above

4. Write two examples of chemi-cal properties and explain whatthey are.

5. The Statue of Liberty was origi-nally a copper color. After beingexposed to the air, she turneda greenish color. What kind ofchange happened? Explain youranswer.

6. Explain how to tell the differ-ence between a physical and achemical property.

Math Skills

7. The temperature of an acidsolution is 25°C. A strip ofmagnesium is added, and thetemperature rises 2°C each min-ute for the first 3 min. Afteranother 5 min, the temperaturehas risen two more degrees.What is the final temperature?

Critical Thinking

8. Making Comparisons Describethe difference between physicaland chemical changes in termsof what happens to the matterinvolved in each kind of change.

9. Applying Concepts Identifytwo physical properties and twochemical properties of a bag ofmicrowave popcorn beforepopping and after.

Topic: Chemical ChangesSciLinks code: HSM0266

Reversing ChangesCan physical and chemical changes be reversed?Many physical changes are easily reversed. Theydo not change the composition of a substance. Forexample, if an ice cube melts, you could freeze theliquid water to make another ice cube. But compo-sition does change in a chemical change. So, mostchemical changes are not easily reversed. Look atFigure 6. The chemical changes that happen whena firework explodes would be almost impossible toreverse, even if you collected all of the materialsmade in the chemical changes.

Another example is the flamma-bility of firewood to form ash,smoke, and heat energy.Flammability tells you whetheror not a substance will burn.

5. Sample answer: A chemicalchange occurred. The copper inthe Statue of Liberty combinedwith oxygen in the air and formednew copper compounds with dif-ferent properties.

6. Sample answer: A physical prop-erty can be observed or deter-mined without changing theidentity of the substance, buta chemical property can beobserved only while the chemi-cal change is occurring.

7. The final temperature is 33°C.8. Sample answer: When matter

undergoes a physical change,its shape or form changes, butits identity remains the same.When matter undergoes a chemical change, its identityand properties change.

9. Sample answer: Physical propertiesof a bag of uncooked popcorninclude an almost flat bag anda bag that is cool to the touch.Chemical properties of a bagof uncooked popcorn includea flammable bag and popcornkernels that pop and changeinto fluffy popcorn when heated.Physical properties of a cookedbag of popcorn include a bagthat is hot, and has increasedin volume. Chemical propertiesof the bag of cooked popcorninclude inability of popcorn tochange back into uncooked ker-nels and flammability of the fluffypopcorn.

CHAPTER RESOURCES


• Section Quizg • Section Reviewg • Vocabulary and Section Summaryg • Datasheet for Quick Lab • Critical Thinkinga


1. Sample answer: A chemical property deter-mines whether or not a substance will reactwith another substance. A chemical changeis a change to a substance that causes it toform a new substance or substances withdifferent properties.

2. d3. d4. One example of a chemical property is the

reactivity of iron with oxygen to form rust.Reactivity tells you whether or not a sub-stance will react with another substance andform new products with new properties.

CRF


LabSkills Practice

Describe the physical properties of four substances.

Identify physical and chemical changes.

Classify four substances by their chemical properties.

• baking powder

• baking soda

• carton, egg, plastic-foam

• cornstarch

• eyedroppers (3)

• iodine solution

• spatulas (4)

• stirring rod

• sugar

• vinegar

• water

White Before Your EyesYou have learned how to describe matter based on its physical and chemical properties. You have also learned some signs that can help you determine whether a change in matter is a physical change or a chemical change. In this lab, you’ll use what you have learned to describe four substances based on their properties and the changes that they undergo.

Procedure

1 Copy Table 1 and Table 2 shown on the next page. Be sure to leave plenty of room in each box to write down yourobservations.

2 Using a spatula, place a small amount of baking powder into three cups of your egg carton. Use just enough bak-ing powder to cover the bottom of each cup. Record your observations about the baking powder’s appear-ance, such as color and texture, in the “Unmixed” column of Table 1.

OBJECTIVES

SAFETY

MATERIALS

Skills PracticeSkills Practice LabLab

White Before Your Eyes

Teacher’s Notes

Time RequiredOne or two 45-minute class periods

Lab Ratings

rTeacher Prep ff

Student Set-Up f

Concept Level ff

Clean Up ff

M A T E R I A L SUse an iodine solution that contains no more than 1.0% iodine in water. You may wish to use a 24-well spot plate or test tubes. A small test tube taped to the bottle makes a great holder for a dropper or pipette and decreases the chance of contamina-tion. A drinking straw cut in half at an angle works well as a spatula; the pointed end is a great scoop, and its large size makes it easy to handle.

Safety CautionWhen iodine is being used, be cer-tain that a functioning eyewash is available. Caution students that iodine can stain skin and clothes. Students should wash their face and hands when finished. Clean up any spills immediately to avoid slips and falls.

CHAPTER RESOURCESWorkbooks

Whiz-Bang Demonstrations• Curious Cubes b• The Dancing Toothpicksg• Does 2 � 2 � 4?gInquiry Labs• Whatever Floats Your Boat a Long-Term Projects & Research Ideas• And We Have Thales to Thank a

CHAPTER RESOURCES


• Datasheets for In-Text Labs• Lab Notes and Answers

Technology

Classroom Videos• Lab Video

• Volumania!• Determining Density• Layering Liquids


3 Use an eyedropper to add 60 drops of waterto the baking powder in the first cup. Stir withthe stirring rod. Record your observations inTable 1 in the column labeled “Mixed withwater.” Clean your stirring rod.

4 Use a clean dropper to add 20 drops of vin-egar to the second cup of baking powder. Stir.Record your observations in Table 1 in the col-umn labeled “Mixed with vinegar.” Clean yourstirring rod.

5 Use a clean dropper to add five drops of iodinesolution to the third cup of baking powder.Stir. Record your observations in Table 1 in thecolumn labeled “Mixed with iodine solution.”Clean your stirring rod. Caution: Be carefulwhen using iodine. Iodine will stain your skinand clothes.

6 Repeat steps 2–5 for each of the other sub-stances (baking soda, cornstarch, and sugar).Use a clean spatula for each substance.

Analyze the Results

1 Examining Data What physical properties doall four substances share?

2 Analyzing Data In Table 2, write the typeof change—physical or chemical—that youobserved for each substance. State the prop-erty that the change demonstrates.

Draw Conclusions

3 Evaluating Results Classify the four sub-stances by the chemical property of reactivity.For example, which substances are reactivewith vinegar (acid)?

Table 1 Observations

Substance Unmixed Mixed with water Mixed with vinegarMixed with

iodine solution

Baking powder

Baking soda

Cornstarch

Sugar

Table 2 Changes and Properties

Mixed with water Mixed with vinegar Mixed with iodine solution

Substance Change Property Change Property Change Property

Baking powder

Baking soda

Cornstarch

Sugar

DO NOT WRITE IN BOOK




Analyze the Results

1. All four substances are whitesolids, and are granular or powdery.

2. See the table at the bottom ofthe page.

Lab NotesRemind students that vinegaris an acid and that they shoulduse caution when handling it.Although Table 2 shows thatbaking powder reacts with water,baking powder is not reactivewith water. Baking powder cancontain baking soda (a base), aweak acid, and a starch. Thebaking soda and the weak acidin baking powder will react witheach other when the bakingpowder is dissolved in water.This reaction produces the bub-bles that students observe inthis experiment.

Disposal InformationDispose of any unreacted iodinesolution by combining all studentsolutions. Decolorize if necessaryby adding 1.0 M Na2S2O3 whilestirring until the dark color disap-pears. Dilute the mixture with atleast 10 times its volume of waterbefore discarding. If local waste-water regulations permit, thediluted solu tion may be poureddown the drain.

2.Mixed with water Mixed (vinegar) Mixed (iodine solution)

Substance Change Property Change Property Change Property

Baking chemical reactivity chemical reactivity physical solubilitypowder with water with acid

Baking physical solubility chemical reactivity physical solubilitysoda with acid

Cornstarch physical solubility physical solubility chemical reactivitywith iodine

Sugar physical solubility physical solubility physical solubilityJoseph Price

H. M. BrowneJunior HighWashington, D.C.

Holt Lab GeneratorCD-ROM

Search for any lab by topic, standard,difficulty level, or time. Edit any labto fit your needs, or create your ownlabs. Use the Lab Materials QuickListsoftware to customize your labmaterials list.

CLASSROOM

TESTED& APPRO

VED

Chapter 2 • Chapter Lab 57

8 The best way to measure the volume of an irregularly shaped solid is to

a. use a ruler to measure the length of each side of the object.

b. weigh the solid on a balance.c. use the water displacement method.d. use a spring scale.

9 Which of the following statements about weight is true?

a. Weight is a measure of the gravita-tional force on an object.

b. Weight varies depending on where the object is located in relation to the Earth.

c. Weight is measured by using a spring scale.

d. All of the above

0 Which of the following statements does NOT describe a physical property of a piece of chalk?

a. Chalk is a solid.b. Chalk can be broken into pieces.c. Chalk is white.d. Chalk will bubble in vinegar.

q Which of the following statements about density is true?

a. Density is expressed in grams.b. Density is mass per unit volume.c. Density is expressed in milliliters.d. Density is a chemical property.

In one or two sentences, explain how the process of measuring the volume of a liquid differs from the process of measuring the volume of a solid.

1 Use each of the following terms in a separate sentence: physical property, chemical property, physical change, and chemical change.

For each pair of terms, explain how the meanings of the terms differ.

2mass and weight

3 inertia and mass

4 volume and density

Multiple Choice

5 Which of the following properties is NOT a chemical property?

a. reactivity with oxygenb. malleabilityc. fl ammabilityd. reactivity with acid

6The volume of a liquid can be expressed in all of the following units EXCEPT

a. grams.b. liters.c. milliliters.d. cubic centimeters.

7 The SI unit for the mass of a substance is the

a. gram.b. liter.c. milliliter.d. kilogram.

USING KEY TERMS

UNDERSTANDING KEY IDEAS

Understanding Key Ideas5. b6. a7. d8. c9. d

10. d11. b

12. Sample answer: The volume of a liquid can be measured by pouring it into a graduated cylinder and reading the scale at the bottom of the meniscus. The volume of a rectangular solid can be determined by multiplying the object’s length, width, and height. The volume of an irregular solid can be measured by measuring water displacement.

ANSWERS

Using Key Terms1. Sample answers: Physical

properties of a substance include color, shape, and den-sity. Flammability is a chemical property of matter. Sugar dis-solving in water is an example of a physical change. When a piece of iron metal rusts it is undergoing a chemical change.

2. Sample answer: Mass is the amount of matter in an object and is always constant. Weight is a measure of the gravitational force, and weight will change, depending on the object’s distance from the Earth or other celestial bodies.

3. Sample answer: Mass is a measure of inertia. The more mass an object has, the more inertia it has.

4. Sample answer: Volume is the amount of space occupied by an object, and density is the amount of mass in a given volume.

Assignment GuideSECTION QUESTIONS

1 2–3, 6–9, 12, 15, 17, 20–21

2 11, 13, 16, 22, 24

3 5, 19, 25

1 and 2 4

2 and 3 1, 10, 14, 23

1, 2, and 3 18


e What is the formula for calculatingdensity?

r List three characteristic properties ofmatter.

Math Skills

t What is the volume of a book thathas a width of 10 cm, a length that is2 times the width, and a height that ishalf the width? Remember to expressyour answer in cubic units.

y A jar contains 30 mL of glycerin(whose mass is 37.8 g) and 60 mL ofcorn syrup (whose mass is 82.8 g).Which liquid is on top? Show yourwork, and explain your answer.

uConcept Mapping Use the followingterms to create a concept map: matter,mass, inertia, volume, milliliters, cubiccentimeters, weight, and gravity.

iApplying Concepts Develop a set ofquestions that would be useful whenidentifying an unknown substance.The substance may be a liquid, a gas,or a solid.

oAnalyzing Processes You are mak-ing breakfast for your friend Filbert.When you take the scrambled eggs tothe table, he asks, “Would you pleasepoach these eggs instead?” What sci-entifi c reason do you give Filbert fornot changing his eggs?

p Identifying Relationships You lookout your bedroom window and seeyour new neighbor moving in. Yourneighbor bends over to pick up a smallcardboard box, but he cannot lift it.What can you conclude about theitem(s) in the box? Use the terms massand inertia to explain how you came toyour conclusion.

aAnalyzing Ideas You may sometimeshear on the radio or on TV that astro-nauts are weightless in space. Explainwhy this statement is not true.

Use the photograph below to answerthe questions that follow.

s List three physical properties of thisaluminum can.

d When this can was crushed, did itundergo a physical change or a chemi-cal change?

f How does the density of the metalin the crushed can compare with thedensity of the metal before the canwas crushed?

g Can you tell what the chemical prop-erties of the can are by looking at thepicture? Explain your answer.

CRITICAL THINKING

INTERPRETING GRAPHICS

CHAPTER RESOURCES


CRF • Chapter Reviewg• Chapter Test Ag• Chapter Test Ba• Chapter Test Cs• Vocabulary Activityg

Workbooks

Study Guide• Study Guide is also available in Spanish.

13. density � mass/volume 14. Characteristic properties include density,

solubility, reactivity with acid, melting point,and boiling point.

15. volume � length � width � height �20 cm � 10 cm � 5 cm � 1,000 cm3

16. Density of glycerin � 37.8 g/30 mL �1.26 g/mL. Density of corn syrup �82.8 g/60 mL � 1.38 g/mL. The glycerin willbe on top because it is less dense thancorn syrup.

Critical Thinking 17. An answer to this

exercise can befound at the endof this book.

18. Answers may vary. Questionsmay include the following top-ics: size, shape, color, weight,density, state, and odor.

19. Sample answer: Cooking eggsinvolves a chemical change. Icannot change the cooked eggsback to raw eggs in order topoach them.

20. Sample answer: If my neighborhas trouble lifting a small box, Iwould conclude that the box’sinertia is large. The box resistsmy neighbor’s attempt to moveit. A large inertia means that themass of the contents of the boxis large.

21. Sample answer: An astronautweighs less in space than onEarth because of the astro-naut’s increased distance fromEarth. But, an astronaut is notweightless because there arestill gravitational forcesbetween the astronaut and allother objects in the universe.

Interpreting Graphics 22. Sample answer: crushed shape,

somewhat shiny, and metallic 23. a physical change 24. The density before and after the

change is the same becausedensity is a characteristic prop-erty of matter.

25. No, chemical properties cannotbe determined simply by look-ing at a substance. Chemicalproperties can only beobserved when a chemicalchange might occur.

Chapter 2 • Chapter Review 59

READINGRead each of the passages below. Then, answer the questions that follow each passage.

Passage 1 Astronomers were studying the motions of galaxies in space when they noticed something odd. They thought that the large gravi-tational force, which causes the galaxies to rotate rapidly, was due to a large amount of mass in the galaxies. Then, they discovered that the mass of the galaxies was not great enough to explain this large gravitational force. So, what was causing the additional gravitational force? One theory is that the universe contains matter that we cannot see with our eyes or our telescopes. Astronomers call this invisible matter dark matter.

1. According to this passage, what did astronomers originally think caused the rotation of the galaxies?

A a lack of inertiaB a large gravitational forceC a small amount of mass in the galaxiesD a small gravitational force

2. Why do you think astronomers use the term dark matter?

F Dark matter refers to dark objects.G Dark matter refers to matter that we

can’t see.H You need a telescope to see dark matter.I All large objects are dark.

3. Which statement is the best summary of the passage?

A The enormous amount of mass in the galaxies explains why the galaxies rotate.

B Dark matter may be responsible for the gravitational force that causes the rotation of galaxies.

C Invisible matter is called dark matter.D Galaxies rotate as they move through the

universe.

Passage 2 Blimps and dirigibles are types of airships. An airship consists of an engine, a large balloon that contains gas, and a gondola that carries passengers and crew. Airships float in air because the gases that the airships contain are less dense than air. In the early 1900s, airships were commonly used for travel, including transatlan-tic flights. Airships were less frequently used after the 1937 explosion and crash of the Hindenburgin New Jersey. The Hindenburg was filled with flammable hydrogen gas instead of helium gas, which is nonflammable.

1. In this passage, what does fl ammable mean?

A able to burnB able to fl oatC able to sink

D not able to burn

2. Which of the following statements is true according to the passage?

F Hydrogen gas is nonfl ammable.G Airships fl oat because they contain gases

that are less dense than air.H Helium gas was used in the Hindenburg.I The gondola contains gas.

3. Which of the following statements about airships is true?

A Airships are still a major mode of transportation.

B Airships now contain nonfl ammable, hydrogen gas.

C Airships consist of an engine, a gondola, and a large balloon.

D Airships traveled only in the United States.

READING

MISCONCEPTIONALERT

Passage 11. B2. G3. B

Question 1: Astronomers believe that galaxies rotate rapidly because of the large gravitational forces that the matter within the galaxies has. For this large gravitational force to exist, there must be a large amount of matter present in the galaxy.

Question 3: The statement in answer B is the best summary of the passage because it is a reasonable statement of what the passage is about. The other three answers restate facts mentioned in the passage.

Passage 21. A2. G3. C

Question 2: Statement G is true because this fact is mentioned in the third sentence of the passage. Answer F is not true because the last sentence states that hydrogen gas is flammable. Statement H is not true because the last sentence states that the Hindenburg was filled with hydro-gen gas. Answer I is not true because the second sentence states that the gondola carries passen-gers and the crew.

Teacher’s NoteTeacher’s NoteTo provide practice under more realistic testing conditions, give students 20 minutes to answer all of the questions in this Standardized Test Preparation.

Answers to the standardized test preparation can help you identify student misconcep-tions and misunderstandings.


Stand

ardized

Test Prep

aration

1. What could you use to tell pyrite (fool’s gold) and gold apart?

A volumeB densityC massD state

2. What do you think would happen if you placed a nugget of pyrite into a beaker of mercury?

F The pyrite would sink.G The pyrite would dissolve.H The mercury and the pyrite would react.I The pyrite would fl oat.

3. If a nugget of pyrite and a nugget of gold each have a mass of 50 g, what can you conclude about the volume of each nugget?

A The volume of pyrite is greater than the volume of gold.

B The volume of pyrite is less than the volume of gold.

C The volumes of the substances are equal.D There is not enough information to

determine the answer.

4. Which substance has the lowest density?

F heliumG pyriteH mercuryI gold

1. Imagine that you have discovered a new element, and you want to fi nd its density. It has a mass of 78.8 g and a volume of 8 cm3.To fi nd the density of the element, you must divide the element’s mass by its volume. What is the density of the element?

A 0.102 g/cm3

B 0.98 g/cm3

C 9.85 g/cm3

D 630.4 g/cm3

2. Many soft drinks come in bottles that contain about 590 mL. If the density of a soft drink is 1.05 g/mL, what is the mass of the drink?

F 0.0018 gG 498.2 gH 561.9 g I 619.5 g

3. If you have 150 g of pure gold and the density of gold is 19.32 g/cm3, what is the volume of your gold nugget?

A 2,898 cm3

B 7.76 cm3

C 0.98 cm3

D 0.13 cm3

4. Three objects have a mass of 16 g each. But their volumes differ. Object A, a liquid, has a volume of 1.2 mL. Object B, a solid, has a volume of 3.2 cm3. Object C, another solid, has a volume of 1.9 cm3. Which object is the least dense?

F object AG object BH object CI There is not enough information to

determine the answer.

The table below shows the properties of different substances. Use the table below to answer the questions that follow.

Read each question below, and choose the best answer.

INTERPRETING GRAPHICS MATH

Properties of Some Substances*

Substance State Density (g/cm3)

Helium Gas 0.0001663

Pyrite Solid 5.02

Mercury Liquid 13.55

Gold Solid 19.32

* at room temperature and pressure

INTERPRETING GRAPHICS1. B2. I3. A4. F

Question 3: Answer A is correct because the density of pyrite is less than the density of gold. To find the volume of a substance, you would divide the mass by the density. Because the density of gold is larger that the density of pyrite, the volume of 50 g of gold would be smaller than the volume of pyrite.

MATH1. C2. I3. B4. G

Question 1: The density of the ele-ment is found by dividing the mass of 78.8 g by the volume of 8 cm3.. Answer C is the correct density.

Question 4: The density of each substance is found by dividing the mass by the volume. The mass of each substance is the same but the vol-umes are different. Because Object B has the largest volume, it is the least dense.

CHAPTER RESOURCES


CRF • Standardized Test Preparation g

State Resources

For specifi c resources for your state, visit go.hrw.com and type in the keyword HSMSTR.

Chapter 2 • Standardized Test Preparation 61

in Action

in Action

Language Arts There are advantages and dis-advantages of each kind of bag.

Write a one-page essay defending your posi-tion on this subject. Support your opinion with facts.

Social Studies Do some research on the history of bone-replacement therapy. Make a poster that shows a timeline of events leading up to current technology.

WRITINGSKILL

Scientific DebatePaper or Plastic? What do you choose at the grocery store: paper or plastic bags? Plastic bags are water-proof and take up less space. You can use them to line waste cans and to pack lunches. Some places will recycle plastic bags. But making 1 ton of plastic bags uses 11 barrels of oil, which can’t be replaced, and produces polluting chemicals. On the other hand, making 1 ton of paper bags destroys 13 to 17 trees, which take years to replace. Paper bags, too, can be reused for lining waste cans and wrapping packages. Recycling paper pol-lutes less than recycling plastic does. What is the answer? Maybe we should reuse both!

Science, Technology,

and Society Building a Better Body Have you ever broken a bone? If so, you probably wore a cast while the bone healed. But what happens if the bone is too damaged to heal? Sometimes, a false bone made from titanium can replace the damaged bone. Titanium appears to be a great bone-replacement material. It is a lightweight but strong metal. It can attach to existing bone and resists chemi-cal changes. But, friction can wear away titanium bones. Research has found that implanting a form of nitrogen on the tita-nium makes the metal last longer.

Scientific Debate

vv-------------------------------------------- GENERAL

Tell students to imagine that the local landfill is becoming full at a faster rate than community leaders originally thought it would be filled. Have students develop a presentation or bro-chure that they could use to convince people in their com-munity to recycle paper and plastic bags as one way to reduce the amount of waste that is put into the landfill. l Interpersonal

Science, Technology,

and Society

Discussion ---------------------------------- GENERAL

Tell students that the nitrogen implanted in the surface of the titanium bones is actually nitro-gen ions that have been blasted into the surface of the titanium by a particle accelerator. The ions bond to the titanium atoms, and the surface becomes harder and smoother. The nitrogen-titanium bond also attracts and holds a thin film of joint fluid that lubricates moving parts of the joint and increases the durability of the bone replacement. Surgeons and scientists are also making replacement bones that use a titanium-cobalt alloy or a cobalt-chrome alloy and a plastic socket.

Answer to Language Arts Activity

Students’ essays should include strong support-ing material for their viewpoint. Some aspects of this debate that would be important to consider in support of their viewpoint include environ-mental, economic, and practical use issues.

Answers to Social Studies Activity

Students’ posters should include information on the history of prosthetics, which dates back to about 500 BCE. References to current technologi-cal advancements should include information about other materials being used in bone and joint replacement.


Mimi SoGemologist and Jewelry Designer A typical day for gemologist and jewelry designer Mimi So involves deciding what materials to work with. When she chooses a gemstone for a piece of jewelry, she must consider the size, hardness, color, grade, and cut of the stone. When choosing a metal to use as a setting for a stone, she must look at the hardness, melting point, color, and malleability of the metal. She needs to choose a metal that not only looks good with a particular stone but also has physical properties that will work with that stone. For example, Mimi So says emeralds are soft and fragile. A platinum setting would be too hard and could damage the emerald. So, emeralds are usually set in a softer metal, such as 18-karat gold.

The chemical properties of stones must also be considered. Heating can burn or discolor some gemstones. Mimi So says, “If you are using pearls in a design that requires heating the metal, the pearl is not a stone, so you cannot heat the pearl, because it would destroy the pearl.”

MathPure gold is 24-karat (24K). Gold that contains 18 parts gold and 6 parts other metals is 18-karat gold. The percent-age of gold in 18K gold is found by dividing the amount of gold by the total amount of the ma terial and then multiplying by 100%. For example,(18 parts gold)/(24 parts total) equals0.75 � 100% � 75% gold. Find the per-centage of gold in 10K and 14K gold.

To learn more about these Science in Action topics, visit go.hrw.com and type in the keyword HP5MATF.

Check out Current Science®

articles related to this chapter by visiting go.hrw.com. Just type in the keyword HP5CS02.

Careers

BackgroundAt a young age, Mimi So helpedout in her parent’s jewelry storeby greeting customers and arranging displays. She eventu-ally went to school and earned a Bachelor of Fine Arts degree in design, and her Gemologist Certification. Though certifica-tion is not required in jewelry making, she says, “It is impor-tant to have a better knowledge of stones and a technical point of view to understand certain processes for working with dia-monds.” However, she adds that some people go to gemology school to get the technical back-ground and come to find that they are disappointed with their real-world jobs. Mimi So advises young people to explore gemol-ogy before going to school. “I think it’s really important that if they are interested in this indus-try or they’re not certain, that they go out there and get a part-time job or a weekend job so that they can truly find out which area that they would actually enjoy doing.”

Answers to Math Activity

The percentage of gold in 10K gold is 41.67%. The percentage of gold in 14K gold is 58.33%.

Chapter 2 • Science in Action 63

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