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In both junior high and
high school, I had trouble
staying focused.
Sue Grafton,
U is for Undertow
Copyright© The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Chapter 1
Chemistry:
Methods and Measurement
Denniston
Topping
Caret
6th Edition
1.1 The Discovery Process
• Chemistry - The study of matter…
– Matter - Anything that has mass and
occupies space
• A table
• A piece paper
– What about air?
• Yes, it is matter
1.1 The Discovery Process
Chemistry:
• the study of matter
• its chemical and physical properties
• the chemical and physical changes
it undergoes
• the energy changes that accompany
those processes
• Energy - the ability to do work to
accomplish some change
1.1 The Discovery Process
MAJOR AREAS OF CHEMISTRY
• Biochemistry - the study of life at the
molecular level
• Organic chemistry - the study of
matter containing carbon and hydrogen
• Inorganic chemistry - the study of
matter containing elements, not organic
• Analytic chemistry - analyze matter to
determine identity and composition
1.1 The Discovery Process
• Physical chemistry - attempts to
explain the way matter behaves
public health
pharmaceutical industry
CHEMISTRY
food science
medical practitioners
forensic sciences
1.1 The Discovery Process
THE SCIENTIFIC METHOD
• The scientific method - a systematic
approach to the discovery of new
information
Characteristics of the scientific process
ƒ Observation
ƒ Formulation of a question
ƒ Pattern recognition
ƒ Developing theories
ƒ Experimentation
ƒ Summarizing information
1.1 The Discovery Process
1.1 The Discovery Process
Models in Chemistry
• To aid in understanding of a
chemical unit or system
– a model is often used
– good models are based on
everyday experience
• Ball and stick methane
model
– color code balls
– sticks show attractive forces
holding atoms together
1.2 Matter and Properties
• Properties - characteristics of matter
– chemical vs. physical
• Three states of matter
1. gas - particles widely separated, no
definite shape or volume solid
2. liquid - particles closer together, definite
volume but no definite shape
3. solid - particles are very close together,
define shape and definite volume
Three States of Water
(a) Solid
(b) Liquid
(c) Gas
1.2 Matter and Properties
Comparison of the Three
Physical States
1.2 Matter and Properties
• Physical property - is observed
without changing the composition
or identity of a substance
• Physical change - produces a
recognizable difference in the
appearance of a substance without
causing any change in its
composition or identity
- conversion from one physical state to
another
- melting an ice cube
Separation by Physical Properties
Magnetic iron is separated from other nonmagnetic
substances, such as sand. This property is used as
a large-scale process in the recycling industry.
1.2 Matter and Properties
• Chemical property - result in a
change in composition and can be
observed only through a chemical
reaction
• Chemical reaction (chemical
change) - a process of
rearranging, removing, replacing,
or adding atoms to produce new
substances
hydrogen + oxygen Æ water
reactants
products
1.2 Matter and Properties
Classify the following as either a
chemical or physical property:
a. Color
b. Flammability
c. Hardness
d. Odor
e. Taste
1.2 Matter and Properties
Classify the following as either a
chemical or physical property:
a. Color - physical
b. Flammability - chemical
c. Hardness - physical
d. Odor - chemical
e. Taste - chemical
1.2 Matter and Properties
Classify the following as either a
chemical or physical change:
a. Boiling water becomes steam
b. Butter turns rancid
c. Burning of wood
d. Mountain snow pack melting in
spring
e. Decay of leaves in winter
1.2 Matter and Properties
Classify the following as either a
chemical or physical change:
a. Boiling water becomes steam (ph)
b. Butter turns rancid (ch)
c. Burning of wood (ch)
d. Mountain snow pack melting in
spring (ph)
e. Decay of leaves in winter (ch)
1.2 Matter and Properties
• Intensive properties - a property
of matter that is independent of the
quantity of the substance
-
Density
-
Specific gravity
-
Battery voltage
• Extensive properties - a property
of matter that depends on the
quantity of the substance
-
Mass
-
Volume
-
Battery capacity
1.2 Matter and Properties
Classification of Matter
• Pure substance - a substance that has only
one component
• Mixture - a combination of two or more pure
substances in which each substance retains
its own identity, not undergoing a chemical
reaction
1.2 Matter and Properties
Classification of Matter
• Element - a pure substance that cannot be
changed into a simpler form of matter by any
chemical reaction
• Compound - a substance resulting from the
combination of two or more elements in a
definite, reproducible way, in a fixed ratio
1.2 Matter and Properties
Classification of Matter
• Mixture - a combination of two or more pure
substances in which each substance retains its own
identity
• Homogeneous - uniform composition, particles
well mixed, thoroughly intermingled
• Heterogeneous – nonuniform composition,
random placement
1.2 Matter and Properties
Classes of Matter
a - pure substance
b - homogeneous mixture
c - heterogeneous mixture
1.3 Significant Figures and
Scientific Notation
• Information-bearing digits or figures in a
number are significant figures
• The measuring device used determines
the number of significant figures a
measurement has
• The amount of uncertainty associated
with a measurement is indicated by the
number of digits or figures used to
represent the information
1.3 Significant Figures and
Scientific Notation
Significant figures - all digits in a number
representing data or results that are known
with certainty plus one uncertain digit
1.3 Significant Figures and
Scientific Notation
Recognition of Significant
Figures
• All nonzero digits are significant
• 7.314 has four significant digits
• The number of significant digits is
independent of the position of the decimal
point
• 73.14 also has four significant digits
• Zeros located between nonzero digits are
significant
• 60.052 has five significant digits
1.3 Significant Figures and
Scientific Notation
Use of Zeros in Significant
Figures
• Zeros at the end of a number (trailing zeros)
are significant if the number contains a
decimal point.
• 4.70 has three significant digits
• Trailing zeros are insignificant if the number
does not contain a decimal point.
• 100 has one significant digit; 100. has three [but
there is a better way to write this]
• Zeros to the left of the first nonzero integer
are not significant.
• 0.0032 has two significant digits
1.3 Significant Figures and
Scientific Notation
How many significant figures are in
the following?
1. 3.400
2. 3004
3. 300.
[3.00 x 102]
4. 0.003040
1.3 Significant Figures and
Scientific Notation
Scientific Notation
• Used to express very large or very small
numbers easily and with the correct
number of significant figures
• Represents a number as a power of ten
• Example:
4,300 = 4.3 x 1,000 = 4.3 x 103
1.3 Significant Figures and
Scientific Notation
• To convert a number greater than 1 to
scientific notation, the original decimal
point is moved x places to the left, and the
resulting number is multiplied by 10x
• The exponent x is a positive number
equal to the number of places the decimal
point moved
5340 = 5.34 x 103
• What if you want to show the above
number has four significant figures?
= 5.340 x 103
1.3 Significant Figures and
Scientific Notation
• To convert a number less than 1 to
scientific notation, the original decimal
point is moved x places to the right, and
the resulting number is multiplied by 10-x
• The exponent x is a negative number
equal to the number of places the decimal
point moved
0.0534 = 5.34 x 10-2
1.3 Significant Figures and
Scientific Notation
• Conversion to scientific notation will
allow to write numbers with
significant figures without the
artificial period at the end of a
number
100. can be written as 1.00x102
• The decimal period without a
decimal number is actually wrong,so
avoid it (legibility, end of sentence)
• Also, write a zero before decimal
point. 0.11 is correct, .11 is not