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Welcome to the Welcome to the World of World of ChemistryChemistry

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The Language of The Language of ChemistryChemistryThe Language of The Language of ChemistryChemistry

The elements, their The elements, their names, and symbols names, and symbols are given on the are given on the

PERIODIC PERIODIC TABLE TABLE

How many elements How many elements are there?are there?

116 elements116 elements

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 Memorize:- SI Base Units (Table 1.2, p.17).- Common decimal prefixes used with SI units (Table

1.3, p.17).- Name and Symbol of elements in the Periodic Table

(cover pages)- Elements that occur as molecules (Figure 2.15, p.58)- Some common monatomic ions of the elements (Figure

2.17, p.60).- Common polyatomic ions (Table 2.5, p.62)- Numerical prefixes for hydrates and binary covalent

compounds (Table 2.6, p.63)

Practice problems in textbook (Answers in Appendix E)  

Recommended works Recommended works

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Chapter 1Chapter 1

Keys to the Study Keys to the Study of Chemistryof Chemistry

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-Chemistry: the Chemistry: the study of matterstudy of matter and and transformationstransformations it undergoes, as well as the it undergoes, as well as the energy involvedenergy involved in such changes. in such changes.

--The Central Themes of ChemistryThe Central Themes of Chemistry Study the observableobservable changes in matter to understand their unobservableunobservable causes.Understand & Explain --- > Understand & Explain --- > Predict & ControlBy investigating the molecular reasons for the processes occurring in our macroscopic world.

1.1 Some Fundamental Definitions1.1 Some Fundamental DefinitionsChemistry and Its Central ThemesChemistry and Its Central Themes

Matter is anything thatMatter is anything that- has mass (sometimes expressed- has mass (sometimes expressed

as weight) as weight) - and occupies a space- and occupies a space

Forms of ENERGY are NOT matter.Forms of ENERGY are NOT matter.example: heat or light does not occupy example: heat or light does not occupy

space and has no mass.space and has no mass.

What is matter?What is matter?

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►Physical Properties: Density, color, melting point, hardness, phase, texture, … are physical properties of matter. Observing a physical property can be done without altering the makeup of a substance.

►Chemical Properties: Chemical composition (what matter is made of), and chemical reactivity (how matter behaves). Observing a chemical property alters the substance.

Physical & Chemical Properties Physical & Chemical Properties

of Matterof Matter

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Physical vs. Chemical changes Physical vs. Chemical changes

Chemical changes occur when new materials are formed by a change in the way atoms are bonded together- Reactivity changes with the - Reactivity changes with the formation of new substances. formation of new substances. - Heat, light, or electrical - Heat, light, or electrical energy is often emitted or energy is often emitted or absorbed.absorbed.

Physical changes are simply change of states with no composition changes of matter.

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Classify each of the following as a

1) physical change or 2) chemical change.

A. ____Burning a candle.

B. ____Ice melting on the street.

C. ____Toasting a marshmallow.

D. ____Cutting a pizza.

Learning CheckLearning Check

Gas Gas (e.g., the air you breathe)- has no definite shape or volume- has no definite shape or volume-is expandable and highly compressibleis expandable and highly compressible-Particles are far apart and move very fastParticles are far apart and move very fast

Liquid Liquid (e.g., the water you drink)- has no definite shape but a - has no definite shape but a

definite volumedefinite volume-is practically incompressibleis practically incompressible-Particles are close together but mobile; they Particles are close together but mobile; they move slowlymove slowly

Solid Solid (e.g., the food you eat)-has a definite shape and volume-has a definite shape and volume-is essentially incompressible-is essentially incompressible- Particles are close together in a fixed - Particles are close together in a fixed arrangement; they move very slowlyarrangement; they move very slowly

States of MatterStates of MatterA A physical state physical state is a form that matter can take.is a form that matter can take.

1.3 The Scientific Approach:1.3 The Scientific Approach:Developing a modelDeveloping a model

- Observations include gathering information and collecting data.

- Hypothesis is a tentative explanation to account for a set of observations and to be tested.

- Laws describe how nature works- Theories explain why observations, hypotheses, or laws

apply under many different observations..

Scientific Inquiry in PracticeScientific Inquiry in PracticeObservation: The sound from a CD in a CD player skips.

Hypothesis 1: The CD player is faulty.

Experiment 1: When I replace the CD with another one, the sound from this second CD is

OK.

Hypothesis 2: The original CD has a defect.

Experiment 2: When I play the original CD in another player, the sound still skips.

Theory: My experimental results indicate the

original CD has a defect.

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1.4 Chemical Problem Solving1.4 Chemical Problem Solving

Physical properties such as height, volume, and temperature that can be measured are called physical quantities. Both a number and a unit of defined size is required to describe physical quantity.

Units and Units and Conversion Conversion FactorsFactors in Calculations in CalculationsA A conversion factor conversion factor

Is a fraction obtained from an equality.Is a fraction obtained from an equality.

Equality: 1 inch = 2.54 cmEquality: 1 inch = 2.54 cm

Can be written as a ratio with a numerator and Can be written as a ratio with a numerator and denominator that express the same quantity in denominator that express the same quantity in different unitsdifferent units

Can be inverted to give two ratios of the same Can be inverted to give two ratios of the same quantity quantity

1 in. 1 in. and and 2.54 cm 2.54 cm

2.54 cm2.54 cm 1 in.1 in.

Learning CheckLearning Check

Write conversion factors for each pair of Write conversion factors for each pair of units:units:

A. liters and mLA. liters and mL

B. hours and minutesB. hours and minutes

C. meters and kilometersC. meters and kilometers

When solving a problem, the idea is to set up an equation so that all unwanted units cancel, leaving only the desired units.

Converting between unit systemsConverting between unit systems

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A Systematic approach to Solving Chemistry Problems

Write the initial and final units. Write a unit plan to convert the initial unit to the

final unit. Write equalities and conversion factors. Use conversion factors to cancel the initial unit

and provide the final unit. Be sure to check unit cancellation.

An Approach to Problem SolvingAn Approach to Problem Solving

What is 165 lb in kg?

STEP 1 Initial 165 lb Final: kgSTEP 2 Plan lb kgSTEP 3 Equalities/Factors 1 kg = 2.20 lb 2.20 lb and 1 kg

1 kg 2.20 lbSTEP 4 Set Up Problem to use conversion factors to

cancel the initial unit and provide the final unit.

165 lb x 1 kg = 74.8 kg

2.20 lb

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Using Two or More Factors

Often, two or more conversion factors are required to obtain the unit needed for the answer.

Unit 1 ---- > Unit 2 ---- > Unit 3

Additional conversion factors are placed in the setup to cancel each preceding unit

Initial unit x factor 1 x factor 2 = Final unit

Unit 1 x Unit 2 x Unit 3 = Unit 3

Unit 1 Unit 2

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Problem Solving

How many minutes are in 1.4 days?

Initial unit: 1.4 days Final unit: min.

Factor 1 Factor 2

Plan: days ---- > hr ---- > min

Set up problem:

1.4 days x 24 hr x 60 min = 2.0 x 103 min

1 day 1 hr

2 SF Exact Exact = 2 SF

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Check the Unit Cancellation

Be sure to check your unit cancellation in the setup.

The units in the conversion factors must cancel to give the correct unit for the answer.

What is wrong with the following setup?1.4 day x 1 day x 1 hr

24 hr 60 min Units = day2/min is not the unit needed

Units don’t cancel properly.

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Learning Check

A bucket contains 4.65 L of water. How many gallons of water is that?

Unit plan: L ---- > qt ---- > gallon

Equalities: 1.06 qt = 1 L

1 gal = 4 qt

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Note: Measurements of Time is not a base 10 system: 1 h = 60 min = 3600 s

1.5 Measurement in Scientific Study

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Metric and SI Prefixes (Table 2)

Common SI-English Equivalent Quantities

Table 1.9

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Learning Check

For each of the following, indicate whether the unit describes 1) length 2) mass or 3) volume.

____ A. A bag of tomatoes is 4.6 kg.

____ B. A person is 2.0 m tall.

____ C. A medication contains 0.50 g aspirin.

____ D. A bottle contains 1.5 L of water.

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Measuring Length and Volume

The meter (m) is the standard measure of length or distance in both the SI and the metric system.

Volume is the amount of space occupied by an object. A volume of a CUBE can be described as a (length)3.

The SI unit for volume is the cubic meter (m3). The metric unit for volume is liter (dm3).

Note: Note: 1 mL = 1 cm1 mL = 1 cm33

DensityDensity

Density ((a measure of compactness)a measure of compactness) relates the mass of an object to its volume. Density is usually expressed in units of grams per cubic centimeter (g/cm3) for solids, and grams per milliliter (g/mL) for liquids.

Density =Density = Mass (g)Mass (g)

Volume (mL or cmVolume (mL or cm33))

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A piece of copper has a mass of 57.54 g. It is 9.36 cm long, 7.23 cm wide, and 0.95 mm thick. Calculate density (g/cm3).

Mercury (Hg) has a density of 13.6 g/cm3. What is the mass of 95 mL of Hg in grams?

ProblemsProblems

TemperatureTemperature is a measure of how hot or cold an object is compared to another object.

HeatHeat flows from the object with a higher temperature to the object with a lower temperature.

Temperature is measured using a thermometer in Celsius, Kelvin, or Farenheit scales

TemperatureTemperature

TTFF = 1.8 T = 1.8 TCC + 32 + 32 TTKK = T= TCC + 273.15 + 273.15 00CC

Lowest possible temperature: -273.15 0C = 0.00 K

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Temperature Temperature ScalesScales

100 100 ooFF38 38 ooCC311 K311 K

oF oC K

Normal body tempe-rature

A person with hypothermia has a body temperature of 34.8°C. What is that temperature in °F? in K?

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1.6 Uncertainty in Measurement

An exact number is obtained When objects are counted

Counting objects2 soccer balls

4 pizzas From numbers in a defined relationship.

Defined relationships1 foot = 12 inches1 meter = 100 cm

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Exact Numbers vs. Measured Numbers

A measuring tool Is used to determine a

quantity such as height or the mass of an object.

Provides numbers for a measurement that are called measured numbers. Copyright © 2007 by Pearson Education, Inc.

Publishing as Benjamin Cummings

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Learning Check

Classify each of the following as exact (E) or

measured (M) numbers.

A. Gold melts at 1064°C.

B. 1 yard = 3 feet

C. The diameter of a red blood cell is 6 x 10-4 cm.

D. There are 6 hats on the shelf.

E. A can of soda contains 355 mL of soda.

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Significant Figures

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Determining Which Digits are Significant

Every experimental measurement has a degree of uncertainty.

The volume, V, at right is certain in the 10’s place, 10mL < V < 20mL

The 1’s digit is also certain, 17mL < V < 18mL

A best guess is needed for the tenths place.

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The markings on the meter stick at the end of the blue line are read as

The first digit 2 plus the second digit 2.7 The last digit is obtained by estimating. The end of the line might be estimated between 2.7–2.8

as half-way (0.5) or a little more (0.6), which gives a reported length of 2.75 cm or 2.76 cm.

Reading a Meter Stick

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Known + Estimated DigitsKnown + Estimated Digits

Significant figures obtained from a measurement include all of the known digits plus the estimated digit.

In the length reported as 2.76 cm, The digits 2 and 7 are certain (known). The last digit 6 was estimated (uncertain). All three digits (2.76) are significant, including the

estimated digit.

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Learning Check

What is the length of the red line?

1) 9.0 cm

2) 9.03 cm

3) 9.08 cm

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For this measurement, the first and second known digits are 4.7

Because the line ends on a mark, the estimated digit in the hundredths place is 0.

This measurement is reported as 4.70 cm.

Zero as the last digit in Measured Number

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Learning Check

A. State the number of significant figures in each of the following measurements:0.030 m 4.050 L 0.0008 g 2.80 m

B. Which answer(s) contains 3 significant figures? 1) 0.4760 2) 0.00476 3) 4.76 x 103

C. All the zeros are significant in

1) 0.00307 2) 25.300 3) 2.050 x 103

D. The number of significant figures in 5.80 x 102 is 1) one 2) two 3) three

Rounding Off Calculated Rounding Off Calculated AnswersAnswersIn calculations,In calculations, Answers must have the same number of significant Answers must have the same number of significant

figures as the measured numbers.figures as the measured numbers.

When the first digit dropped is When the first digit dropped is 4 or less4 or less,,

the retained numbers remain the same. the retained numbers remain the same.

To round 45.832 to 3 significant figuresTo round 45.832 to 3 significant figures

drop the digits 32 = 45.8drop the digits 32 = 45.8

When the first digit dropped is When the first digit dropped is 5 or greater5 or greater,,

the last retained digit is increased by 1.the last retained digit is increased by 1.

To round 2.4884 to 2 significant figuresTo round 2.4884 to 2 significant figures

drop the digits 884 = 2.5 (drop the digits 884 = 2.5 (increase by 0.1)increase by 0.1)

Multiplication and Multiplication and DivisionDivision

When When multiplying or dividingmultiplying or dividing use use

The same number of significant figures as the The same number of significant figures as the measurement with the fewest significant digits.measurement with the fewest significant digits.

Rounding rules or adding zeros are applied to Rounding rules or adding zeros are applied to obtain the correct number of significant obtain the correct number of significant figures.figures.

Example:Example:

110.5 x 0.048 = 5.304 = 5.3 (rounded)110.5 x 0.048 = 5.304 = 5.3 (rounded)

4 SF 2 SF calculator 2 SF4 SF 2 SF calculator 2 SF

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Learning Check

Give an answer for the following with the correct

number of significant figures:

A. 2.19 x 4.2 =

1) 9 2) 9.2 3) 9.198

B. 4.311 ÷ 0.07 =

1) 61.59 2) 62 3) 60

C. 2.54 x 0.0028 =

0.0105 x 0.060

1) 11.3 2) 11 3) 0.041

Adding Significant ZerosAdding Significant Zeros Sometimes a calculated answer requires more Sometimes a calculated answer requires more

significant digits. Then significant digits. Then one or more zeros must one or more zeros must be addedbe added..

Example: When the calculated numbers should Example: When the calculated numbers should have 3 significant figures,have 3 significant figures,Calculated answerCalculated answer Zeros added to Zeros added to

give 3 significant figuresgive 3 significant figures

44 4.4.00001.51.5 1.51.5000.20.2 0.20.20000 12 12 12. 12.00

Learning CheckLearning Check

Give the answers for the following calculations Give the answers for the following calculations with correct numbers of significant figures:with correct numbers of significant figures:

A. 800.00 cm x 2.00 cm A. 800.00 cm x 2.00 cm

B. 1.20 g / 2 bags B. 1.20 g / 2 bags

Addition and SubtractionAddition and Subtraction

When When adding or subtractingadding or subtracting useuse

The same number of decimal places as the The same number of decimal places as the measurement with the fewest decimal places.measurement with the fewest decimal places.

Rounding rules to adjust the number of digits Rounding rules to adjust the number of digits in the answer.in the answer.

0.0.5 5 one decimal placeone decimal place

+ 1.+ 1.3434 two decimal placestwo decimal places

1.1.8484 calculated answercalculated answer

1.1.8 8 answer withanswer with one decimal placeone decimal place

Learning CheckLearning Check

For each calculation, give the answer with For each calculation, give the answer with correct number of significant figures.correct number of significant figures.

A. 235.05 + 19.6 + 2 = A. 235.05 + 19.6 + 2 =

1) 2571) 257 2) 256.7 2) 256.7 3) 256.65 3) 256.65

B. 58.925 - 18.2B. 58.925 - 18.2 ==

1) 40.7251) 40.725 2) 40.73 2) 40.73 3) 40.73) 40.7

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Exact and Measured Numbers in Equalities

Equalities between units of

The same system are definitions and use exact numbers.

Different systems (metric and U.S.) use measured numbers and count as significant figures.

Example: 1ft = 12 in. (exact)

1 in. = 2.54 cm (measured)

Precision and AccuracyPrecision and Accuracy