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Is the study of matter,

its properties,

the changes that matter undergoes,

and

the energy associated with these changes.

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Definitions

Chemical Properties those which the substance shows as it interacts with, or transforms into, other substances such as flammability, corrosiveness

Matter anything that has mass and volume -the “stuff” of the universe: books, planets, trees, teachers, students

Properties the characteristics that give each substance a unique identity

Physical Properties those which the substance shows by itself without interacting with another substance such as color, melting point, boiling point, density

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Figure 1.1

Physical change

A substance alters its physical form, not its composition

Chemical change

A substance is converted into a different substance

The distinction between physical and chemical change.

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Some Characteristic Properties of CopperTable 1.1

Physical Properties Chemical Properties

reddish brown, metallic luster

easily shaped into sheets(malleable) and wires

(ductile)

good conductor of heatand electricity

density = 8.95 g/cm3

melting point = 10830C

boiling point = 25700C

slowly forms a basic blue-greensulfate in moist air

reacts with nitric acid and sulfuric acid

slowly form a deep-bluesolution in aqueous ammonia

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Figure 1.2 The physical states of matter.

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Sample Problem 1.1

Distinguishing Between Physical and Chemical Change

PROBLEM: Decide whether each of the following process is primarily a physical or a chemical change, and explain briefly:

SOLUTION:

(a) Frost forms as the temperature drops on a humid winter night.

(b) A cornstalk grows from a seed that is watered and fertilized.

(c) Dynamite explodes to form a mixture of gases.

(d) Perspiration evaporates when you relax after jogging.

(e) A silver fork tarnishes slowly in air.

(a) physical change (b) chemical change (c) chemical change

(d) physical change (e) chemical change

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energy due to the position of the object or energy from a chemical reaction

Potential Energy

Kinetic Energy energy due to the motion of the object

EnergyEnergy is the capacity to do work.

Potential and kinetic energy can be interconverted.

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EnergyEnergy is the capacity to do work. Figure 1.3B

less stable

more stable

change in potential energy EQUALSkinetic energy

A system of two balls attached by a spring. The potential energy gained by a stretched spring is converted to kinetic energy when the moving balls are released.

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EnergyEnergy is the capacity to do work. Figure 1.3C

less stable

more stable

change in potential energy EQUALSkinetic energy

A system of oppositely charged particles. The potential energy gained when the charges are separated is converted to kinetic energy as the attraction pulls these charges together.

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Scientific Approach: Developing a Model

Observations : Natural phenomena and measured events; universally consistent ones can be stated as a natural law.

Hypothesis: Tentative proposal that explains observations.

Experiment: Procedure to test hypothesis; measures one variable at a time.

Theory (Model):Set of conceptual assumptions that explains data from accumulated experiments; predicts related phenomena.

Further Experiment: Tests predictions based on model.

revised if experiments do not support it

altered if predictions do not support it

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Alchemist at Work

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Lavoisier(1743 – 1794)

• Debunked phlogiston theory

• Demonstrated the true nature of combustion

• Named oxygen

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A Systematic Approach to Solving Chemistry Problems

•Problem statement

•Plan

Clarify the known and unknown.

Suggest steps from known to unknown.

Prepare a visual summary of steps.

•Solution

•Check

Comment and Follow-up Problem

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Sample Problem 1.2 Converting Units of Length

PROBLEM: To wire your stereo equipment, you need 325 centimeters (cm) of speaker wire that sells for $0.15/ft. What is the price of the wire?

PLAN: Known - length (in cm) of wire and cost per length ($/ft)We have to convert cm to inches and inches to ft followed by finding the cost for the length in ft.

length (cm) of wire

length (ft) of wire

length (in) of wire

Price ($) of wire

2.54 cm = 1 in

12 in = 1 ft

1 ft = $0.15

Follow up Problem 1.2

A furniture factory needs 31.5 ft2 of fabric to upholster one chair. The supplier sends the fbric in bolts of exactly 200 m2. What is the maximum number of chairs that can be upholstered by 3 bolts of fabric?

1 m = 3.281 ft

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Table 1. 2 SI Base Units

Physical Quantity (Dimension) Unit Name

Unit Abbreviation

mass

meter

kg

length

kilogram

m

time second s

temperature kelvin K

electric current ampere A

amount of substance mole mol

luminous intensity candela cd

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Common Decimal Prefixes Used with SI Units Table 1.3

Prefix PrefixSymbol

Word ConventionalNotation

ExponentialNotation

tera T trillion 1,000,000,000,000 1x1012

giga G billion 1,000,000,000 1x109

mega M million 1,000,000 1x106

kilo k thousand 1,000 1x103

hecto h hundred 100 1x102

deka da ten 10 1x101

----- ---- one 1 1x100

deci d tenth 0.1 1x10-1

centi c hundredth 0.01 1x10-2

milli m thousandth 0.001 1x10-3

micro millionth 0.000001 1x10-6

nano n billionth 0.000000001 1x10-9

pico p trillionth 0.000000000001 1x10-12

femto f quadrillionth 0.000000000000001 1x10-15

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Substance Physical State Density (g/cm3)

Densities of Some Common Substances*Table 1.5

Hydrogen Gas 0.0000899

Oxygen Gas 0.00133

Grain alcohol Liquid 0. 789

Water Liquid 0.998

Table salt Solid 2.16

Aluminum Solid 2.70

Lead Solid 11.3

Gold Solid 19.3

*At room temperature(200C) and normal atmospheric pressure(1atm).

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Sample Problem 1.5 Calculating Density from Mass and Length

PROBLEM:

Lithium (Li) is a soft, gray solid that has the lowest densityof any metal. If a slab of Li weighs 1.49 x 103 mg and has sides that measure 20.9 mm by 11.1 mm by 11.9 mm, what is the density of Li in g/cm3 ?

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Figure 1.12 The freezing and boiling points of water.

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Temperature Scales and Interconversions

Kelvin ( K ) - The “Absolute temperature scale” begins at absolute zero and only has positive values.

Celsius ( oC ) - The temperature scale used by science, formally called centigrade, most commonly used scale around the world; water freezes at 0oC, and boils at 100oC.

Fahrenheit ( oF ) - Commonly used scale in the U.S. for our weather reports; water freezes at 32oF and boils at 212oF.

Kelvin = oC + 273.15 oC = Kelvin - 273.15

oF = (9/5) oC + 32oC = [oF - 32 ] 5/9

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Sample Problem 1.6 Converting Units of Temperature

A child has a body temperature of 38.7 oC.

(a) If normal body temperature is 98.6 oF, does the child have a fever?

(b) What is the child’s temperature in Kelvin?

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The number of significant figures in a measurement depends upon the measuring device.

Figure 1.14

32.3 oC32.33 oC

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Rules for Determining Which Digits are Significant Leading zeros are not significant.

•If the measured quantity has a decimal point start at the left of the number and move right until you reach the first nonzero digit.•Count that digit and every digit to it’s right as significant.

Numbers such as 5300 L are assumed to only have 2 significant figures. A terminal decimal point (or a bar) is often used to clarify the situation, but scientific notation is the best!

Zeros that end a number and lie either after or before the decimal point are significant; thus 1.030 ml has four significant figures, and 5300. L has four significant figures also.

•If the measured quantity does not have a decimal point start at the right of the number and move leftt until you reach the first nonzero digit.•Count that digit and every digit to it’s left as significant.

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Sample Problem 1.7 Determining the Number of Significant Figures

For each of the following quantities, determine the number of significant figures in each quantity.

SOLUTION:

(b) 0.1044 g(a) 0.0030 L (c) 53,069 mL

(e) 57,600. s(d) 0.00004715 m (f) 0.0000007160 cm3

(b) 4sf(a) 2sf (c) 5sf

(e) 5sf(d) 4sf (f) 4sf

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Rules for Rounding Off Numbers1. If the digit removed is more than 5, the preceding number increases by 1. 5.379 rounds to 5.38 if three significant figures are retained and to 5.4 if two significant figures are retained.

2. If the digit removed is less than 5, the preceding number is unchanged. 0.2413 rounds to 0.241 if three significant figures are retained and to 0.24 if two significant figures are retained.

3.If the digit removed is 5, the preceding number increases by 1 if it is odd and remains unchanged if it is even.17.75 rounds to 17.8, but 17.65 rounds to 17.6. If the 5 is followed only by zeros, rule 3 is followed; if the 5 is followed by nonzeros, rule 1 is followed: 17.6500 rounds to 17.6, but 17.6513 rounds to 17.7

4. Be sure to carry two or more additional significant figures through a multistep calculation and round off only the final answer.

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Precision and Accuracy Errors in Scientific Measurements

Random Error - In the absence of systematic error, some values that are higher and some that are lower than the actual value.

Precision -Refers to reproducibility or how close the measurements are to each other.

Accuracy -Refers to how close a measurement is to the real value.

Systematic error - Values that are either all higher or all lower than the actual value.

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Figure 1.16

precise and accurate

precise but not accurate

Precision and accuracy in the laboratory.

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systematic error

random error

Precision and accuracy in the laboratory.Figure 1.16 continued