1 Chapter 1Chemistry: An Introduction Chemistry is… the science that deals with the materials of the universe and the changes that these materials undergo Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

2 Scientific Method The scientific method is the process used by scientists to explain observations in nature. Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

3 Scientific Method The scientific method involves  Making Observations  Writing a Hypothesis  Doing Experiments  Proposing a Theory Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

4 Features of the Scientific Method Observations  Facts obtained by observing and measuring events in nature. Hypothesis  A statement that explains the observations. Experiments  Procedures that test the hypothesis. Theory  A model that describes how the observations occur using experimental results.

5 Summary of the Scientific Method Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

6 Everyday Scientific Thinking Observation: 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.

7 Theory versus Law Natural Law: A summary of observed behavior Theory: An explanation of behavior Theories explain Laws!

8 Learning Check The part of scientific thinking indicated in each is 1) observation2) hypothesis 3) experiment4) theory A. A blender does not work when plugged in. B. The blender motor is broken. C. The plug has malfunctioned. D. The blender does not work when plugged into a different outlet. E. The blender needs repair.

9 Solution The part of scientific thinking indicated in each is 1) observation2) hypothesis 3) experiment4) theory A. (1) A blender does not work when plugged in. B. (2) The blender motor is broken. C. (2) The plug has malfunctioned. D. (3) The blender does not work when plugged into a different outlet. E. (4) The blender needs repair.

10 Chapter 2: Measurements and Calculations You make a measurement every time you  Measure your height.  Read your watch.  Take your temperature.  Weigh a cantaloupe. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

11 Measurement in Chemistry In chemistry we  Measure quantities.  Do experiments.  Calculate results.  Use numbers to report measurements.  Compare results to standards. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

12 Measurement In a measurement  A measuring tool is used to compare some dimension of an object to a standard.  Of the thickness of the skin fold at the waist, calipers are used. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

13 Stating a Measurement In every measurement, a number is followed by a unit. Observe the following examples of measurements: Number and Unit 35 m 0.25 L 225 lb 3.4 hr

14 The Metric System (SI) The metric system or SI (international system) is  A decimal system based on 10.  Used in most of the world.  Used everywhere by scientists.

15 Units in the Metric System In the metric and SI systems, one unit is used for each type of measurement: MeasurementMetricSI Lengthmeter (m)meter (m) Volumeliter (L)cubic meter (m 3 ) Massgram (g)kilogram (kg) Timesecond (s)second (s) TemperatureCelsius (  C)Kelvin (K)

16 Length Measurement Length  Is measured using a meter stick.  Uses the unit of meter (m) in both the metric and SI systems. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

17 Inches and Centimeters The unit of an inch  Is equal to exactly 2.54 centimeters in the metric (SI) system. 1 in. = 2.54 cm Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

18 Volume Measurement Volume  Is the space occupied by a substance.  Uses the unit liter (L) in metric system. 1 L = 1.06 qt  Uses the unit m 3 (cubic meter) in the SI system.  Is measured using a graduated cylinder. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

19 Mass Measurement The mass of an object  Is a measure of the quantity of material it contains.  Is measured on a balance.  Uses the unit gram (g) in the metric system.  Uses the unit kilogram (kg) in the SI system. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

20 Temperature Measurement The temperature  Indicates how hot or cold a substance is.  Is measured on the Celsius (  C) scale in the metric system.  On this thermometer is 18ºC or 64ºF.  In the SI system uses the Kelvin (K) scale. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

21 Time Measurement Time measurement  Uses the unit second (s) in both the metric and SI systems.  Is based on an atomic clock that uses a frequency emitted by cesium atoms. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

22 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. Learning Check

23 For each of the following, indicate whether the unit describes 1) length 2) mass or 3) volume. 2 A. A bag of tomatoes is 4.6 kg. 1 B. A person is 2.0 m tall. 2 C. A medication contains 0.50 g aspirin. 3 D. A bottle contains 1.5 L of water. Solution

24 Learning Check Identify the measurement that has a SI unit. A. John’s height is 1) 1.5 yd2) 6 ft 3) 2.1 m B. The race was won in 1) 19.6 s2) 14.2 min3) 3.5 hr C. The mass of a lemon is 1) 12 oz2) kg3) 0.6 lb D. The temperature is 1) 85  C2) 255 K3) 45  F

25 Solution A. John’s height is 3) 2.1 m B. The race was won in 1) 19.6 s C. The mass of a lemon is 2) kg D. The temperature is 2) 255 K

26 Scientific Notation Scientific notation  Is used to write very large or very small numbers.  For the width of a human hair ( m) is written 8 x m  For a large number such as s is written 4.5 x 10 6 s Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

27 Writing Numbers in Scientific Notation  A number in scientific notation contains a coefficient and a power of 10. coefficient power of ten coefficient power of ten 1.5 x x  To write a number in scientific notation, the decimal point is placed after the first digit.  The spaces moved are shown as a power of ten = 5.2 x = 3.78 x spaces left 3 spaces right

28 Comparing Numbers in Standard and Scientific Notation Here are some numbers written in standard format and in scientific notation. Number in Standard Format Scientific Notation Diameter of the Earth m1.28 x 10 7 m Mass of a human 68 kg 6.8 x 10 1 kg Length of a virus cm3 x cm

29 Learning Check Select the correct scientific notation for each. A ) 8 x ) 8 x ) 0.8 x B ) 7.2 x ) 72 x ) 7.2 x 10 -4

30 Solution Select the correct scientific notation for each. A ) 8 x B ) 7.2 x 10 4

31 Learning Check Write each as a standard number. A. 2.0 x ) 2002) ) B. 1.8 x ) ) )

32 Solution Write each as a standard number. A. 2.0 x ) B. 1.8 x )

33 Uncertainty in Measurement A measuring tool  Is used to determine a quantity such as height or the mass of an object.  Provides numbers for a measurement called measured numbers. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

34. l l.... l l.... l 4.. cm  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

35 Known + Estimated Digits In the length reported as 2.76 cm,  The digits 2 and 7 are certain (known).  The final digit 6 was estimated (uncertain).  All three digits (2.76) are significant including the estimated digit.

36 Learning Check. l l.... l l.... l 10.. cm What is the length of the red line? 1) 9.0 cm 2) 9.03 cm 3) 9.04 cm

37 Solution. l l.... l l.... l 10.. cm The length of the red line could be reported as 2) 9.03 cm or 3) 9.04 cm The estimated digit may be slightly different. Both readings are acceptable.

38. l l.... l l.... l 5.. cm  For this measurement, the first and second known digits are 4.5.  Because the line ends on a mark, the estimated digit in the hundredths place is 0.  This measurement is reported as 4.50 cm. Zero as a Measured Number

39 Significant Figures in Measured Numbers Significant figures  Obtained from a measurement include all of the known digits plus the estimated digit.  Reported in a measurement depend on the measuring tool.

40 All non-zero numbers in a measured number are significant. MeasurementNumber of Significant Figures cm4 5.6 ft lb m5 Counting Significant Figures

41 Sandwiched zeros  Occur between nonzero numbers.  Are significant. MeasurementNumber of Significant Figures 50.8 mm min lb m 5 Sandwiched Zeros

42 Trailing zeros  Follow non-zero numbers in numbers without decimal points.  Are usually place holders.  Are not significant. MeasurementNumber of Significant Figures cm kg mL g 5 Trailing Zeros

43 Leading zeros  Precede non-zero digits in a decimal number.  Are not significant. Measurement Number of Significant Figures mm oz lb mL 3 Leading Zeros

44 Significant Figures in Scientific Notation In scientific notation  All digits including zeros in the coefficient are significant. Scientific NotationNumber of Significant Figures 8 x 10 4 m1 8.0 x 10 4 m x 10 4 m3

45 State the number of significant figures in each of the following measurements: A m B L C g D m Learning Check

46 State the number of significant figures in each of the following measurements: A m2 B L4 C g1 D m3 Solution

47 A. Which answer(s) contains 3 significant figures? 1) ) ) 4.76 x 10 3 B. All the zeros are significant in 1) ) ) x 10 3 C. The number of significant figures in 5.80 x 10 2 is 1) one2) two3) three Learning Check

48 A. Which answer(s) contains 3 significant figures? 2) ) 4.76 x 10 3 B. All the zeros are significant in 2) ) x 10 3 C. The number of significant figures in 5.80 x 10 2 is 3) three Solution

49 In which set(s) do both numbers contain the same number of significant figures? 1) 22.0 and ) and 4.00 x ) and Learning Check

50 Solution In which set(s) do both numbers contain the same number of significant figures? 3) and Both numbers contain two (2) significant figures.

51 Examples of Exact Numbers An exact number is obtained  When objects are counted Counting objects 2 soccer balls 4 pizzas  From numbers in a defined relationship. Defined relationships 1 foot = 12 inches 1 meter = 100 cm

52 Exact Numbers TABLE 1.5 Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

53 Learning Check A. Exact numbers are obtained by 1. using a measuring tool 2. counting 3. definition B. Measured numbers are obtained by 1. using a measuring tool 2. counting 3. definition

54 Solution A. Exact numbers are obtained by 2. counting 3. definition B. Measured numbers are obtained by 1. using a measuring tool

55 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 cm. D.__There are 6 hats on the shelf. E.__A can of soda contains 355 mL of soda.

56 Classify each of the following as exact (E) or measured (M) numbers. A. M A measuring tool is required. B. E This is a defined relationship. C. M A measuring tool is used to determine length. D. E The number of hats is obtained by counting. E. M The volume of soda is measured. Solution

57 Calculated Answers In calculations,  Answers must have the same number of significant figures as the measured numbers.  Calculator answers must often be rounded off.  Rounding rules are used to obtain the correct number of significant figures. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

58 Rounding Off Calculated Answers When the first digit dropped is 4 or less,  The retained numbers remain the same. To round to 3 significant figures drop the digits 32 = 45.8  When the first digit dropped is 5 or greater, the last retained digit is increased by 1. To round to 2 significant figures drop the digits 884 = 2.5 (increase by 0.1)

59 Adding Significant Zeros  Sometimes a calculated answer requires more significant digits. Then one or more zeros are added. Calculated answerZeros added to give 3 significant figures

60 Learning Check Adjust the following calculated answers to give answers with three significant figures: A cm B g C. 8.2 L

61 Solution Adjust the following calculated answers to give answers with three significant figures: A. 825 cm First digit dropped is greater than 4. B gFirst digit dropped is 4. C LSignificant zero is added.

62 Calculations with Measured Numbers In calculations with measured numbers, significant figures or decimal places are counted to determine the number of figures in the final answer. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

63 When multiplying or dividing use  The same number of significant figures as the measurement with the fewest significant figures.  Rounding rules to obtain the correct number of significant figures. Example: x = = 5.3 (rounded) 4 SF 2 SF calculator 2 SF Multiplication and Division

64 Give an answer for the following with the correct number of significant figures: A x 4.2 = 1) 9 2) 9.2 3) B ÷ 0.07 = 1) ) 62 3) 60 C x = x ) 11.32) 11 3) Learning Check

65 A x 4.2 = 2) 9.2 B ÷ 0.07 = 3) 60 C x = 2) x On a calculator, enter each number followed by the operation key x   = = 11 (rounded) Solution

66 When adding or subtracting use  The same number of decimal places as the measurement with the fewest decimal places.  Rounding rules to adjust the number of digits in the answer one decimal place two decimal places 26.54calculated answer 26.5 answer with one decimal place Addition and Subtraction

67 For each calculation, round the answer to give the correct number of significant figures. A = 1) 257 2) ) B = 1) ) ) 40.7 Learning Check

68 A rounds to 257 Answer (1) B round to 40.7Answer (3) Solution

69 Prefixes A prefix  In front of a unit increases or decreases the size of that unit.  Make units larger or smaller than the initial unit by one or more factors of 10.  Indicates a numerical value. prefixvalue 1 kilometer=1000 meters 1 kilogram=1000 grams

70 Metric and SI Prefixes TABLE 1.6 Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cmings Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

71 Indicate the unit that matches the description: 1. A mass that is 1000 times greater than 1 gram. 1) kilogram2) milligram3) megagram 2. A length that is 1/100 of 1 meter. 1) decimeter2) centimeter3) millimeter 3. A unit of time that is 1/1000 of a second. 1) nanosecond 2) microsecond 3) millisecond Learning Check

72 Indicate the unit that matches the description: 1. A mass that is 1000 times greater than 1 gram. 1) kilogram 2. A length that is 1/100 of 1 meter. 2) centimeter 3. A unit of time that is 1/1000 of a second. 3) millisecond Solution

73 Select the unit you would use to measure A. Your height 1) millimeters2) meters 3) kilometers B. Your mass 1) milligrams2) grams 3) kilograms C. The distance between two cities 1) millimeters2) meters 3) kilometers D. The width of an artery 1) millimeters2) meters 3) kilometers Learning Check

74 A. Your height 2) meters B. Your mass 3) kilograms C. The distance between two cities 3) kilometers D. The width of an artery 1) millimeters Solution

75 An equality  States the same measurement in two different units.  Can be written using the relationships between two metric units. Example: 1 meter is the same as 100 cm and 1000 mm. 1 m=100 cm 1 m=1000 mm Metric Equalities

76 Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings Measuring Length Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cmings Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

77 Measuring Volume Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

78 Measuring Mass  Several equalities can be written for mass in the metric (SI) system 1 kg =1000 g 1 g =1000 mg 1 mg = g 1 mg =1000 µg Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cmings Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

79 Indicate the unit that completes each of the following equalities: A m = 1) 1 mm 2) 1 km3) 1dm B g = 1) 1 mg2) 1 kg3) 1dg C. 0.1 s = 1) 1 ms2) 1 cs3) 1ds D m = 1) 1 mm 2) 1 cm3) 1dm Learning Check

80 Indicate the unit that completes each of the following equalities: A. 2) 1000 m = 1 km B. 1) g = 1 mg C. 3) 0.1 s = 1 ds D. 2) 0.01 m = 1 cm Solution

81 Complete each of the following equalities: A. 1 kg = 1) 10 g2) 100 g 3) 1000 g B. 1 mm =1) m2) 0.01 m 3) 0.1 m Learning Check

82 Complete each of the following equalities: A. 1 kg = 1000 g (3) B. 1 mm = m (1) Solution

83 Equalities  Use two different units to describe the same measured amount.  Are written for relationships between units of the metric system, U.S. units, or between metric and U.S. units. For example, 1 m = 1000 mm 1 lb = 16 oz 2.20 lb = 1 kg Equalities

84 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.

85 Some Common Equalities TABLE 1.9 Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

86 Equalities on Food Labels The contents of packaged foods  In the U.S. are listed as both metric and U.S. units.  Indicate the same amount of a substance in two different units. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings