Chapter 1 Learning Objectives•Distinguish Science from Technology•Define Alchemy and Natural Philosophy•Briefly describe the contributions of Bacon, Galileo, and Carson to the perceptions of science.•Define Hypothesis, Scientific Law, Scientific Theory, and Scientific Model, and explain their relationships in science.•Define Risk and Benefit, and give an example of each.•Estimate a Desirability Quotient from benefit and risk data.•Give an example of a use of Chemistry in your daily life and in society at large.•Distinguish Basic Research from Applied Research.•Differentiate: Mass & Weight; Physical & Chemical Change; Physical & Chemical Properties.•Classify matter according to state and as mixture, substance, compound, and/or element.•Assign proper units of measurements to observations and manipulate units in conversions.•Calculate the density, mass or volume of an object given the two other quantities.•Distinguish between heat and temperature.•Explain how the temperature scales are related.•Use critical thinking to evaluate claims and statements.

MatterMatter

• Science & Technology

• Matter

• Physical and Chemical Changes

• Pure Substances

• Mixtures

A Science for All SeasonsChemistry is the study of matter and its changes.

Everything we do involves chemistry.

July 8, 2011 Space Shuttle Atlantis lifts off from Launch Pad 39B at

Kennedy Space Center, FL. Squid in Space are on Board!!

Photo Credit NASA

ScienceScience & Technology & Technology

See the launch: http://www.youtube.com/watch?v=tqrDWa7Eabk

• Everything that has mass and volume is called matter.

What is Matter?What is Matter?

Water is present in three phases…name ‘em!

Green and Sustainable Chemistry

Green chemistry uses materials and processes that are intended to prevent or reduce pollution at its source.

Sustainable chemistry is designed to meet the needs of the present generation without compromising the needs of future generations.

ScienceScience has five characteristics. Science is

•Testable

•Reproducible

•Explanatory

•Predictive

•Tentative

Scientific models are tangible items or pictures used to represent invisible processes.

Science

Elena O'Brien, scientific support rep for antibody maker Abcam, shows the new look for leather still

sexy, now office-appropriate.

Who are these guys? What are they looking at?

So which one is a scientific model? ..really?

Molecular ModelingMolecules are groups of two or more atoms held together by chemical bonds.

Molecular models are three-dimensional representations of molecules.

Check this out:http://jmol.sourceforge.net/

• All matter, regardless of state, undergoes physical and chemical changes.

• These changes can be microscopic or macroscopic.

Changes in Latitude…Changes in Latitude…Changes in Matter…Changes in Matter…

Properties of MatterProperties of Matter

What is a Physical Change?What is a Physical Change?• A physical change occurs when the

substance changes state but does not change its chemical composition.

• The form or appearance has changed, but the properties of that substance are the same (i.e. it has the same melting point, boiling point, chemical composition, etc.)

• Dry Ice is Sublime…. http://www.youtube.com/watch?v=W3PkuaYYOtg&feature=related

• Others: cutting a piece of wood into smaller pieces, etc. Watch this…http://www.youtube.com/watch?v=fy81xU6vBC8

Physical Change: ExamplesPhysical Change: Examples

• A chemical change occurs when a substance changes into something new. This occurs due to heating, chemical reaction, etc.

• You can tell a chemical change has occurred if the density, melting point or freezing point of the original substance changes.

• Many common signs of a chemical change can be seen (bubbles forming, mass changed, etc).

• I love Bill Nye…• http://www.youtube.com/watch?v=5BF4We7qMf0&feature=related

Chemical Changes:Chemical Changes:

• Reaction with acids• Reaction with bases

(alkalis)• Reaction with oxygen

(combustion)• Ability to act as

oxidizing agent

• Ability to act as reducing agent

• Reaction with other elements

• Decomposition into simpler substances

• Corrosion

Chemical Changes: ExamplesChemical Changes: Examples

• Methane Hydrate….zoiks!

http://www.netl.doe.gov/technologies/oil-gas/futuresupply/methanehydrates/maincontent.htm

• Physical and chemical properties may be intensive or extensive.

• Better check this out…

http://www.youtube.com/watch?v=m0IH3Hgy3oI&feature=related

• Intensive properties such as density, color, and boiling point do not depend on the amount of the sample of matter and can be used to identify substances.

• Extensive properties such as mass and volume do depend on the quantity of the sample.

• Physical properties are those that we can determine without changing the identity of the substance we are studying.

• The physical properties of sodium metal can be observed or measured. It is a soft, lustrous, silver-colored metal with a relatively low melting point and low density.

• Hardness, color, melting point and density are all physical properties.

• Chemical properties describe the way a substance can change or react to form other substances. These properties, then, must be determined using a process that changes the identity of the substance of interest.

• One of the chemical properties of alkali metals such as sodium and potassium is that they react with water. To determine this, we would have to combine an alkali metal with water and observe what happens.

• This is nutz: http://www.youtube.com/watch?v=m55kgyApYrY

• In other words, we have to define chemical properties of a substance by the chemical changes it undergoes.

Matter is identified as either a….

• Pure Substance: Element or Compound,

or a….

• Mixture: Homogeneous Mixture or Heterogeneous Mixture

• Can a pure substance be further broken down or purified by physical means? (Give examples)

• Does each pure substance have its own characteristic properties that are different from the set of properties of any other pure substance? (Give examples)

• Do PS have constant composition?

• Can PS be changed in identity and

properties by chemical methods?

• Do PS have constant properties?

Mixtures are two or more pure substances that are NOT chemically combined.

•Do mixtures have constant boiling points?

•Do mixtures have constant melting points?

Compounds• Can be decomposed

into simpler substances by chemical changes, always in a definite ratio

• Molecules?

Elements• Cannot be

decomposed into simpler substances by chemical changes

• Atoms?

Elements

• Variable composition

• Components retain their characteristic properties

• May be separated into pure substances by physical methods

• Mixtures of different compositions may have widely different properties

Homogenous mixtures look the same throughout but can be separated by physical means (dissolution, centrifuge, gravimetric filtering, etc.). Examples: milk, yogurt

• Solutions are homogenous mixtures that do not scatter light.

• These homogeneous mixtures are created when something is completely dissolved in pure water.

•They are easily separated by distillation or evaporation.

Examples: sugar water, salt water

• Heterogeneous mixtures are composed of large pieces that are easily separated by physical means (ie. density, polarity, metallic properties).

• Examples?

• Do not have same composition throughout

• Components are distinguishable

Examples: fruit salad, vegetable soup, etc.

Matter

•Solids•Liquids•Gases•Plasma

(And how the Kinetic Molecular Theory affects each)

•Have a definite shape•Have a definite volume

Molecules are held close together and there is very little movement between them.

Kinetic Molecular Theory

•Have an indefinite shape•Have a definite volume

Kinetic Molecular Theory:Atoms and molecules have more space between them than a solid does, but less than a gas (ie. It is more “fluid”.)

•Have an indefinite shape•Have an indefinite volume

Kinetic Molecular Theory:

Molecules are moving in random patterns with varying amounts of distance between the particles.

At 100°C, water becomes water vapor, a gas. Molecules can move randomly over large distances.

Below 0°C, water solidifies to become ice. In the solid state, water molecules are held together in a rigid structure.

Between 0°C and 100 °C, water is a liquid. In the liquid state, water molecules are close together, but can move about freely.

Changing states requires energy in either the form of heat. Changing states may also be due to the change in pressure in a system.

Heat of formation, Hf.Heat of vaporization, Hv

• Plasma is by far the most common form of matter.

• Plasma in the stars and in the tenuous space between them makes up over 99% of the visible universe and perhaps most of that which is not visible.

• Plasma is a high energy electrically charged mixture of ions and electrons. While plasma is the most abundant phase of matter in the universe, on earth it only occurs in a few limited places. Plasma appears on earth only in places like lightning bolts, flames, auroras, and fluorescent lights.

On earth we live upon an island of "ordinary" matter. The different states of matter generally found on earth are solid, liquid, and gas. We have learned to work, play, and rest using these familiar states of matter. Sir William Crooke's, an English physicist, identified a fourth state of matter, now called plasma, in 1879. Plasma temperatures and densities range from relatively cool and tenuous (like aurora) to very hot and dense (like the central core of a star). Ordinary solids, liquids, and gases are both electrically neutral and too cool or dense to be in a plasma state. The word "PLASMA" was first applied to ionized gas by Dr. Irving Langmuir, an American chemist and physicist, in 1929.

(Above)

X-ray view of Sun from Yohkoh, ISAS and NASA

Star formation in the Eagle Nebula

Space Telescope Science Institute, NASA

(below)

Plasma radiation within the Princeton Tokamak during operation.

Laser plasma interaction during inertial confinement fusion test at the University of Rochester.

                                         

    Both inertial and magnetic confinement fusion research have focused on confinement and heating processes with dramatic results. The next stage of operating power reactors will produce about 1 GW of power and operate at 120 million degrees Kelvin.

Plasma consists of a collection of free-moving electrons and ions - atoms that have lost electrons. Energy is needed to strip electrons from atoms to make plasma. The energy can be of various origins: thermal, electrical, or light (ultraviolet light or intense visible light from a laser). With insufficient sustaining power, plasmas recombine into neutral gas.

Plasma can be accelerated and steered by electric and magnetic fields which allows it to be controlled and applied. Plasma research is yielding a greater understanding of the universe. It also provides many practical uses: new manufacturing techniques, consumer products, and the prospect of abundant energy.

Products manufacturedusing plasmas impact our daily lives:

EXAMPLES:

•Computer chips and integrated circuits

•Computer hard drives

•Electronics

•Machine tools

•Medical implants and prosthetics

•Audio and video tapes

•Aircraft and automobile engine parts

•Printing on plastic food containers

•Energy-efficient window coatings

•High-efficiency window coatings

•Safe drinking water

•Voice and data communications components

•Anti-scratch and anti-glare coatings on eyeglasses and other optics

•Waste processing

•Coatings and films

•Electronics

•Computer chips and integrated circuits

•Advanced materials (e.g., ceramics)

•High-efficiency lighting

Plasma technologies are important in industries with annual world markets approaching $200 billion

                         

   

Water Purification

SystemsPlasma-based sources can emit intense beams of UV & X ray radiation or electron beams for a variety of environmental applications.

For water sterilization, intense UV emission disables the DNA of microorganisms in the water which then cannot replicate. There is no effect on taste or smell of the water and the technique only takes about 12 seconds.

                  

This plasma-based UV method is effective against all water-born bacteria and viruses. Intense UV water purification systems are especially relevant to the needs of developing countries because they can be made simple to use and have low maintenance, high throughput and low cost. Plasma-based UV water treatment systems use about 20,000 times less energy than boiling water!

•There is no observable change in the quantity of matter during a chemical reaction or a physical change.

•In other words, matter cannot be created nor destroyed. It is just converted from one form to another

Measurement of Matter

Measurement of Matter

Density

Density is defined as the amount of matter in a given amount of space.

d = m/V

The density of copper is 8.94 g/cm3.

Density: Practice Problem

Calculate the density of a metal sample with a mass of 18.96 g and a volume of 4.31 cm3.

d = m/V

= 18.96 g/4.31cm3

= 4.40 g/cm3

Numbers in Chemistry: Accuracy & Precision

• Why Measure? CO2? Heat? O3? Radiation? Fossil Fuels? Hydrogen Economy?

• Exact Numbers vs. Measurements…What’s the difference?

A Visit from Ironman…or is that “Fe”-man?

• Ironman knows how to measure things with great accuracy

• In Class Activity: L, W, T of your Chemistry text! Volume?

• Were you precise?

• Accurate?

• Both?

• How do you know?

• What is a “true value”, AKA “accepted value”?

A Game of Chance? Skill?

• What’s best? Accuracy or Precision?• How can this objective be achieved in science?• Does this connect to the lab? How?

Are You Sure You Are Uncertain?

• What’s the difference between these two pictures?

• Whys does it matter to me?

• Which measuring instrument is better?

• What makes it better?• Hmmm…uncertainty?

Instrument Uncertainty• OK ± What? Why?• Certainty vs. an estimated digit on

a measuring instrument• Obtain a measuring instrument

from lab & explain to partner what the estimated digit in a measurement has to do with uncertainty.

Mr. Tyler & Mr. Bean give extra help to a Chemistry student. (Which one is “Beaker”?)

Test Your Knowledge!!1) What is the instrument uncertainty for the 100 mL graduated cylinders we use in lab?2) What is the instrument uncertainty for the 100 mL beakers we use in the lab?

Significant Figures Rule!!! There are three rules on determining how many significant figures are in a

number:

1. Non-zero digits are always significant.

2. Any zeros between two significant digits are significant.

3. A final zero or trailing zeros in the decimal portion ONLY are significant.

• Focus on these rules and learn them well. They will be used extensively throughout the remainder of this course. You would be well advised to do as many problems as needed to nail the concept of significant figures down tight and then do some more, just to be sure.

• Please remember that, in science, all numbers are based upon measurements (except for a very few that are defined). Since all measurements are uncertain, we must only use those numbers that are meaningful. A common ruler cannot measure something to be 22.4072643 cm long. Not all of the digits have meaning (significance) and, therefore, should not be written down. In science, only the numbers that have significance (derived from measurement) are written.

Significant Figures…The Rules in More DetailSignificant figures a) All non-zero digits are significant e.g. 1.234 has 4 significant figures. The information

conveyed by the digits is that there is one unit, 2 numbers of 0.1mm, 3 numbers of 0.01 mm and 4 numbers of 0.001 mm. Therefore each digit conveys specific information regarding that place value.

b) Zeroes between non-zero digits are significant e.g. 12.004 has 5 significant figures The two zeroes in the value convey the information that there are zero numbers of 0.1mm and zero numbers of 0.01 mm. Note that there is significant information about smaller units and larger ones.

c) At the end of a number all zeroes are significant, even after the decimal point e.g. 9.100 has 4 significant figures The two zeroes are specifically conveying the information that there are zero numbers of 0.01 mm and zero numbers of 0.001 mm.

d) At the end of a number all zeroes are usually significant if before the decimal point. e.g. 4000 has four significant figures, This implies that the digit filling the units place is not definitely known

e) Zeroes which merely assign place value to a non zero digit are not significant. e.g. If 4000 is correct to the nearest ten, it has only three significant figures. This implies that the digit filling the units place is not definitely known and if 4000 is correct to the nearest hundred it has 2 significant figures. This implies that the digit filling the units place and the tens place are not definitely known. e.g. when the population of a country is said to be 900,000,000 the figure is probably correct to the nearest 100 million. Thus there are 9 units of size 108 units. That is to say, this number has just one significant figure, even though there are nine digits reported.

f) Zeroes reported at the beginning of a number before or after the decimal point are always non-significant. These are also placeholder zeroes. 007 metre = 7 x 10o m ............................1 sig. fig.

0.007 metre = 7 x 10-3 m ...........................1 sig. fig.0.070 metre = 7.0 x 10-2 m.........................2 sig. fig.

Significant Figures & Measurement

• Sig Fig’s are BASED on measurements.

• The number of Sig Fig’s you report in a measurement depends on the ACCURACY of the measuring device.

Hmm…What’s a Derived Unit??

• Density• How do you calculate

density?• Do you need to make

measurements? How many?

• How could you calculate the density of air at sea level?

• What is a hematocrit?

Energy: Heat and TemperatureEnergy is the ability to do work or transfer heat.

Energy exists in two major forms:• Potential energy is stored energy.• Kinetic energy is energy in motion.

Heat vs. Temperature

What is the difference between Heat & Temperature?

Heat is energy that is transferred from hotter objects to cooler objects.

Temperature is the average kinetic energy of the atoms or molecules that make up an object.

Temperature Scales

Units of Heat

Heat energy is often measured in calories or joules.

• One calorie (cal) is the amount of heat required to change the temperature of 1.00 g of water 1.00 oC.

• A calorie is 4.184 joules (J).

1 cal = 4.184 J

Food Calories

A food calorie (Cal, “C” is capitalized) is actually a kilocalorie.

1 Cal = 1 kcal = 1000 cal = 4184 J

Energy

• What is energy?• What units quantify energy?

(cal, Cal, Joule?)• What is a calorie? A Calorie?

…a joule?• Law of Conservation of

Energy?

• SH H2O = 4.184joules/g•oC

James Prescott Joule

Hmm..what’s more energy? Cal or cal?

Physical Properties of Water• USGS Site:

http://ga.water.usgs.gov/edu/waterproperties.html

1) Explain why water is considered an excellent thermal buffer and why this is ecologically significant.

2) Water has it’s maximum density at 4oC, not 0oC. Explain why this occurs and how it is ecologically significant.

Unit Analysis, Factor-Label Method, Dimensional Analysis, Bridge

Building…..all synonyms!• "I thought I knew everything and that speech was the only thing that

mattered in high school. When Mr. Bean taught our Chemistry class unit analysis, I didn't care about it at all. I was making plans for the weekend with my girlfriend who loved me because I was a speech team stud with offers from Brown, Princeton and Harvard and not because of Chemistry. While my homies were home solving unit analysis problems, I was practicing a speech. Then one day I was hit hard at a speech tournament. Splat…no mo swag. I totally clutched on my speech, no points, zippo. I was despondent. My girl friend dumped me. My parents, who used to brag about my speech stats, started getting on my case about my grades. I decided to throw myself into my school work. But I couldn't understand anything. I would get wrong answers all of the time. I now realize that my failure in school came from never having learned unit analysis. I finally decided to learn unit analysis. After three hours of studying unit analysis I get it. My swag is back. My speechie homies are chillin’. Last weekend I placed first in the speech tournament. My girlfriend came back to me and my parents are off my case.” Jeff

Unit AnalysisWhat's the Method?

Example 1: This is a structured way of helping you to convert units. With this method, you can easily and automatically convert very complex units if you have the conversion formulas. The method involves the following steps

Example: Convert 6.0 cm to km

1. Write the term to be converted, (both number and unit) 6.0 cm2. Write the conversion formula's 100 cm = .00100 km3. Make a fraction of the conversion formula, such that…..

a) if the unit in step 1 is in the numerator, that same unit in step 3 must be in the denominator.

b) if the unit in step 1 is in the denominator, that same unit in step 3 must be in the numerator. Since the numerator and denominator are equal, the fraction must equal

6.0 cm .00100 km   100 cm   

              

4. Multiply the term in step 1 by the fraction in step 3.5. Perform the indicated calculation rounding the answer to the correct number of significant figures. 0.000060

km or 6.0 E -5 km

..and finally…everybody and mean everbody talks…about

sigfigs!• http://www.youtube.com/watch?

v=X5G9tIe84lE&feature=related

• ..and from my generation…a little Dixie Chicken:

• http://www.youtube.com/watch?v=3z-GwdaKrn8&feature=related