1.1. MATTER & MASS
Spencer L. Seager
Michael R. Slabaugh
•  Matter is anything that has mass and occupies space.
www.cengage.com/chemistry/seager
Chapter 1:
Matter, Measurements,
and Calculations
•  Mass is a measurement of the amount of matter in an
object.
•  Mass is independent of the location of an object.
•  An object on the earth has the same mass as the same
object on the moon.
Jennifer P. Harris
WEIGHT
Measurement
•  Weight is a measurement of the gravitational force acting
on an object.
•  Weight depends on the location of an object.
•  An object weighing 1.0 lb on earth weighs about 0.17 lb
on the moon.
You make a measurement
every time you
§  Measure your height.
§  Read your watch.
§  Take your temperature.
§  Weigh a cantaloupe.
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Stating a Measurement
Why and How We Measure
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
Scientists attempt to describe nature in an
objective way through measurement.
Measurements are expressed in units;
officially accepted units are called
standard units.
Major systems of units:
1.  Metric/SI
2.  British (used by the U.S., but no longer by
the British!)
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© 2010 Pearson Education, Inc.
6
1
Units in the Metric System
Learning Check
In the metric and SI systems, one unit is used for each
type of measurement:
Measurement
Length
Volume
Mass
Time
Temperature
Metric
meter (m)
liter (L)
gram (g)
second (s)
Celsius (°C)
SI
meter (m)
cubic meter (m3)
kilogram (kg)
second (s)
Kelvin (K)
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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Solution
8
The Metric System (SI)
For each of the following, indicate whether the unit
describes 1) length 2) mass or 3) volume.
The metric system or SI (international system) is
§  A decimal system based on 10.
§  Used in most of the world.
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.
§  Used everywhere by scientists.
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THE USE OF PREFIXES
10
COMMONLY USED METRIC UNITS
•  Prefixes are used to relate basic and derived units.
•  The common prefixes are given in the following table:
2
1.2. Properties and Changes:
Physical & Chemical
Learning Check
•  PHYSICAL PROPERTIES OF MATTER
•  Physical properties can be observed or
measured without attempting to change the
composition of the matter being observed.
•  Examples: color, shape and mass
1 m = ________ cm
100 cm
2 Kg = _______ g
2000 g
3 L = ________ ml
3000 ml
•  CHEMICAL PROPERTIES OF MATTER
•  Chemical properties can be observed or
measured only by attempting to change the
matter into new substances.
•  Examples: flammability and the ability to
react (e.g. when vinegar and baking soda
are mixed)
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Example: Physical Properties of Elements
The physical properties of an element
§  Are observed or measured without changing its identity.
§  Include the following:
Shape
Color
Odor
Taste
Density
Melting point
Boiling Point
Example: Physical Properties of Elements
Some physical properties of
copper are:
Color
Luster
Melting point
Boiling point
Conduction
of electricity
Conduction
of heat
Red-orange
Very shiny
1083°C
2567°C
Excellent
Excellent
15
16
PHYSICAL & CHEMICAL CHANGES
Learning Check:
•  PHYSICAL CHANGES OF MATTER
•  Physical changes take place without a
change in composition.
•  Examples: freezing, melting, or
evaporation of a substance (e.g.
water)
Which of the following is a physical change?
•  CHEMICAL CHANGES OF MATTER
•  Chemical changes are always
accompanied by a change in
composition.
•  Examples: burning of paper and the
fizzing of a mixture of vinegar and
baking soda
1.  Food digesting
2.  Sodium reacting
with water
3.  Methanol burning
in air
4.  Liquid helium
boiling
3
1.3. PARTICULATE MODEL OF MATTER
•  All matter is made up of tiny
particles called molecules and
atoms.
Atoms
§  Are tiny particles of matter.
•  MOLECULES
•  A molecule is the smallest
particle of a pure substance that
is capable of a stable
independent existence.
§  Of an element are similar
and different from other
elements.
•  ATOMS
•  Atoms are the particles that
make up molecules.
§  Are rearranged to form
new combinations in a
chemical reaction.
§  Of two or more different
elements combine to form
compounds.
Copyright © 2007 by Pearson Education, Inc.
Publishing as Benjamin Cummings
20
MOLECULE CLASSIFICATION
MOLECULE CLASSIFICATION (continued)
•  Diatomic molecules contain two atoms.
•  HOMOATOMIC MOLECULES
•  The atoms contained in homoatomic molecules are of
the same kind.
•  Triatomic molecules contain three atoms.
•  Polyatomic molecules contain more than three atoms.
•  HETEROATOMIC MOLECULES
•  The atoms contained in heteroatomic molecules are of
two or more kinds.
homoatomic
heteroatomic
MOLECULE CLASSIFICATION EXAMPLE
1.4. CLASSIFICATION OF MATTER
•  Classify the molecules in these diagrams using the terms
diatomic, triatomic, or polyatomic molecules.
•  Matter can be classified into several categories based on
chemical and physical properties.
•  Solution: H2O2 is a polyatomic molecule, H2O is a triatomic
molecule, and O2 is a diatomic molecule.
•  Classify the molecules using the terms homoatomic or
heteroatomic molecules.
•  PURE SUBSTANCES
•  Pure substances have a constant composition and a fixed
set of other physical and chemical properties.
•  Example: pure water
(always contains the same
proportions of hydrogen and
oxygen and freezes at a specific
temperature)
•  Solution: H2O2 and H2O are heteroatomic molecules and O2
is a homoatomic molecule.
4
CLASSIFICATION OF MATTER (continued)
HETEROGENEOUS MIXTURES
•  MIXTURES
•  The properties of a sample of a heterogeneous mixture
depends on the location from which the sample was taken.
•  Mixtures can vary in composition and properties.
•  Example: mixture of table sugar and water
(can have different proportions of sugar and water)
•  A glass of water could contain one, two, three, etc.
spoons of sugar.
•  Properties such as
sweetness would be
different for the mixtures
with different proportions.
•  A pizza pie is a heterogeneous mixture. A piece of crust
has different properties than a piece of pepperoni taken from
the same pie.
HOMOGENEOUS MIXTURES
ELEMENTS
•  Homogeneous mixtures are also called solutions. The
properties of a sample of a homogeneous mixture are the
same regardless of where the sample was obtained from the
mixture.
•  Elements are pure substances that are made up of
homoatomic molecules or individual atoms of the same
kind.
•  Examples: oxygen gas made up of homoatomic molecules
and copper metal made up of individual copper atoms
•  Samples taken from any part of a mixture made up of one
spoon of sugar mixed
with a glass of water will
have the same properties,
such as the same taste.
COMPOUNDS
MATTER CLASSIFICATION SUMMARY
•  Compounds are pure substances that are made up of
heteroatomic molecules or individual atoms (ions) of two or
more different kinds.
•  Examples: pure water made up of heteroatomic molecules
and table salt made up of sodium atoms (ions) and chlorine
atoms (ions)
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MATTER CLASSIFICATION EXAMPLE
TEMPERATURE SCALES
•  Classify H2, F2, and HF using the classification scheme from
the previous slide.
•  The three most
commonly-used
temperature scales
are the Fahrenheit,
Celsius and Kelvin
scales.
•  The Celsius and
Kelvin scales are
used in scientific
work.
•  Solution:
•  H2, F2, and HF are all pure substances because they
have a constant composition and a fixed set of physical
and chemical properties.
•  H2 and F2 are elements because they are pure
substances composed of homoatomic molecules.
•  HF is a compound because it is a pure substance
composed of heteroatomic molecules.
TEMPERATURE CONVERSIONS
•  Readings on one temperature scale can be converted to the
other scales by using mathematical equations.
•  Converting Fahrenheit to Celsius.
5
!
C = ! F ! 32
9
•  Converting Celsius to Fahrenheit.
9
!
F = ! C + 32
5
•  Converting Kelvin to Celsius.
(
TEMPERATURE CONVERSION PRACTICE
)
•  Covert 22°C and 54°C to Fahrenheit and Kelvin.
( )
!
!
F=
9
22 ! C + 32 = 71.6 ! F ! 72 ! F
5
(
)
!
K = 22 C + 273 = 295 K
C = K ! 273
•  Converting Celsius to Kelvin.
!
K = C + 273
!
9
F = 54 ! C + 32 = 129.2 ! F ! 129 ! F
5
(
)
K = 54 ! C + 273 = 327 K
1.7. SCIENTIFIC NOTATION
1.7.SCIENTIFIC NOTATION (continued)
•  Scientific notation provides a convenient way to express
very large or very small numbers.
•  Numbers written in scientific notation consist of a product of
two parts in the form M x 10n, where M is a number between
1 and 10 (but not equal to 10) and n is a positive or negative
whole number.
•  The number M is written
with the decimal in the
standard position.
•  STANDARD DECIMAL POSITION
•  The standard position for a decimal is to the right of the
first nonzero digit in the number M.
•  SIGNIFICANCE OF THE EXPONENT n
•  A positive n value indicates the number of places to the
right of the standard position that the original decimal
position is located.
•  A negative n value indicates
the number of places to
the left of the standard
position that the original
decimal position is located.
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Learning Check
Solution
Select the correct scientific notation for each.
A. 0.000 008
1) 8 x 106
2) 8 x 10-6
3) 0.8 x 10-5
B. 72 000
1) 7.2 x 104
2) 72 x 103
Select the correct scientific notation for each.
A. 0.000 008
2) 8 x 10-6
B. 72 000
1) 7.2 x 104
3) 7.2 x 10-4
37
38
1.7. SCIENTIFIC NOTATION MULTIPLICATION
1.7. SCIENTIFIC NOTATION DIVISION
•  Multiply the M values (a and b) of each number to give a
product represented by M'.
•  Add together the n values (y and z) of each number to give a
sum represented by n'.
•  Write the final product as M' x 10n'.
•  Move decimal in M' to the standard position and adjust n' as
necessary.
•  Divide the M values (a and b) of each number to give a
quotient represented by M'.
•  Subtract the denominator (bottom) n value (z) from the
numerator (top) n value (y) to give a difference represented by
n'.
•  Write the final quotient as M' x 10n'.
•  Move decimal in M' to the standard position and adjust n' as
necessary.
(a ! 10 )(b ! 10 )= (a ! b)(10 )
(3.0 " 10 )(4.0 " 10 )= (3.0 " 4.0)(10
y
8
z
y+z
-2
= 12 ! 10
y
( 8 )+( !2 )
)
6
= 1.2 ! 10
(3.0 ! 10 ) 3.0
(4.0 ! 10 )= 4.0 (10
8
(a ' 10 )= &$ a #!(10 )
(b ' 10 ) % b "
7
z
y-z
(8)- (-2)
-2
)
= 0.75 ! 1010
= 7.5 ! 10 9
1.8. SIGNIFICANT FIGURES
1.8. SIGNIFICANT FIGURES (continued)
•  Significant figures are the numbers in a measurement that represent the
certainty of the measurement, plus one number representing an estimate.
•  The answer obtained by multiplication or division must contain
the same number of significant figures (SF) as the quantity
with the fewest number of significant figures used in the
calculation.
•  COUNTING ZEROS AS SIGNIFICANT FIGURES
•  Leading zeros are never significant figures.
•  Buried zeros are always
significant figures.
•  Trailing zeros are generally
significant figures with decimal.
•  Trailing zeros are not
significant figures without decimal.
4.325 ! 4.5 = 19.4625 " 19
(4 SF)! (2 SF) =
2 SF
4.325 ÷ 4.5 = 0.961 ! 0.96
(4 SF)÷ (2 SF) =
2 SF
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1.8. SIGNIFICANT FIGURES (continued)
ROUNDING RULES FOR NUMBERS
•  The answer obtained by addition or subtraction must contain
the same number of places to the right of the decimal (prd)
as the quantity in the calculation with the fewest number of
places to the right of the decimal.
•  If the first of the nonsignificant figures to be dropped from an
answer is 5 or greater, all the nonsignificant figures are
dropped and the last remaining significant figure is increased
by one.
•  If the first of the nonsignificant figures to be dropped from an
answer is less than 5, all nonsignificant figures are dropped
and the last remaining significant figure is left unchanged.
5.325 + 5.5 = 10.825 ! 10.8
(3 prd)+ (1prd) =
1 prd
5.325 ! 5.5 = !0.175 " !0.2
(3 prd)! (1prd) =
1 prd
Round 10.825 to 1place to the right of the decimal.
⇒10.8
Round −0.175 to 1 place to the right of the decimal.
⇒ −0.2
EXACT NUMBERS
1.9. USING UNITS IN CALCULATIONS
•  Exact numbers are numbers that have no uncertainty (they
do not affect significant figures).
•  A number used as part of a defined relationship between
quantities is an exact number (e.g. 100 cm = 1 m).
•  A counting number obtained by counting individual objects
is an exact number (e.g. 1 dozen eggs = 12 eggs).
•  A reduced simple fraction is an exact number (e.g. 5/9 in
equation to convert ºF to ºC).
•  The factor-unit method for solving numerical problems is a
four-step systematic approach to problem solving.
•  Step 1: Write down the known or given quantity. Include both the
numerical value and units of the quantity.
•  Step 2: Leave some working space and set the known quantity
equal to the units of the unknown quantity.
•  Step 3: Multiply the known quantity by one or more factors, such
that the units of the factor cancel the units of the known quantity
and generate the units of the unknown quantity.
•  Step 4: After you generate the desired units of the unknown
quantity, do the necessary arithmetic to produce the final numerical
answer.
SOURCES OF FACTORS
FACTOR UNIT METHOD EXAMPLES
•  The factors used in the factor-unit method are fractions
derived from fixed relationships between quantities. These
relationships can be definitions or experimentally measured
quantities.
•  An example of a definition that provides factors is the
relationship between meters and centimeters: 1m = 100cm.
This relationship yields two factors:
•  A length of rope is measured to be 1834 cm. How many meters is
this?
1m
100 cm
and
100 cm
1m
•  Solution: Write down the known quantity (1834 cm). Set the known
quantity equal to the units of the unknown quantity (meters). Use
the relationship between cm and m to write a factor (100 cm = 1 m),
such that the units of the factor cancel the units of the known
quantity (cm) and generate the units of the unknown quantity (m).
Do the arithmetic to produce the final numerical answer.
1834 cm
=
m
& 1m #
1834 cm$
! = 18.34 m
% 100 cm "
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1.10. PERCENTAGE
EXAMPLE PERCENTAGE CALCULATION
•  The word percentage means per one hundred. It is the
number of items in a group of 100 such items.
•  A student counts the money she has left until pay day and
finds she has $36.48. Before payday, she has to pay an
outstanding bill of $15.67. What percentage of her money
must be used to pay the bill?
•  PERCENTAGE CALCULATIONS
•  Percentages are calculated using the equation:
%=
•  Solution: Her total amount of money is $36.48, and the part is
what she has to pay or $15.67. The percentage of her total is
calculated as follows:
part
! 100
whole
•  In this equation, part represents the number of specific items
included in the total number of items.
%=
part
15.67
! 100 =
! 100 = 42.96%
whole
36.48
1.11. DENSITY
DENSITY CALCULATION EXAMPLE
•  Density is the ratio of the mass of a sample of matter divided
by the volume of the same sample.
•  A 20.00 mL sample of liquid is put into an empty beaker that
had a mass of 31.447 g. The beaker and contained liquid
were weighed and had a mass of 55.891 g. Calculate the
density of the liquid in g/mL.
density =
mass
volume
•  Solution: The mass of the liquid is the difference between the
mass of the beaker with contained liquid, and the mass of the
empty beaker or 55.891g -31.447 g = 24.444 g. The density
of the liquid is calculated as follows:
or
d=
m
v
d=
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Accuracy and Precision
The accuracy of a measurement signifies how close it
comes to the true (or accepted) value- that is, how
nearly correct it is.
#(!04%2Y).42/$5#4)/.4(%.!452%/&3#)%.#%!.$0(93)#3
m 24.444 g
g
=
= 1.222
v 20.00 mL
mL
Precision
refers to the agreement among repeated
measurements-that is, the spread of the
measurements or how close they are together.
The more precise a group of measurements,
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What is chemistry
a science that studies the composition and
properties of matter, and the changes that matter
undergoes.
10