Chapter1 120319075352-phpapp02

Chapter 1
Basic Concepts
About Matter

Chapter 1
Table of Contents
Copyright © Cengage Learning. All rights reserved 2
1.1 Chemistry: The Study of Matter
1.2 Physical States of Matter
1.3 Properties of Matter
1.4 Changes in Matter
1.5 Pure Substances and Mixtures
1.6 Elements and Compounds
1.7 Discovery and Abundance of the Elements
1.8 Names and Chemical Symbols of the Elements
1.9 Atoms and Molecules
1.10 Chemical Formulas

Chemistry: The Study of Matter
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Section 1.1
• The field of study concerned with the
characteristics, composition, and
transformations of matter.
What is Chemistry?

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Section 1.1
• Anything that has mass and occupies space.
– Mass refers to the amount of matter present
in a sample.
Matter

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Section 1.1
• Includes all things – both living and nonliving
 Examples: plants, soil, air, bacteria
• Various forms of energy such as heat, light, and
electricity are not considered to be matter.
• The universe is composed entirely of matter and
energy.
Matter

Section 1.2
Physical States of Matter
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• The classification of a given matter sample in
terms of physical state is based on whether its
shape and volume are definite or indefinite.
• Matter exists in three physical states:
 Solid
 Liquid
 Gas

Section 1.2
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Examples of the Three States of Matter

Section 1.2
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• Physical state characterized by a definite shape
and a definite volume.
Solid

Section 1.2
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Structure of a Solid

Section 1.2
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• Physical state characterized by an indefinite
shape and a definite volume.
• Always takes the shape of its container to the
extent that it fills the container.
Liquid

Section 1.2
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Structure of a Liquid

Section 1.2
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• Physical state characterized by an indefinite
shape and an indefinite volume.
• Always completely fills its container, adopting
both the container’s volume and its shape.
Gas

Section 1.2
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Structure of a Gas

Section 1.2
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• The state of matter observed for a particular
substance depends on its:
– Temperature
– Surrounding pressure
– Strength of the forces holding its structural
particles together

Section 1.2
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Water Can Be Found in All Three States Simultaneously

Section 1.3
Properties of Matter
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• Distinguishing characteristic of a substance that
is used in its identification and description.
• Each substance has a unique set of properties
that distinguishes it from all other substances.
• Two General Types:
 Physical
 Chemical
Property

Section 1.3
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• Characteristic of a substance that can be
observed without changing the basic identity of
the substance.
– Color, odor, physical state, melting point,
boiling point, and hardness
Physical Property

Section 1.3
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Concept Check
To measure the boiling point of a substance, a
liquid must be changed into a gas. Why is
boiling point considered a physical property
when a gas’ appearance is much different from
that of a liquid?
Although the appearance is different, the
substance is still the same. It’s chemical identity has
not changed.

Section 1.3
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• Characteristic of a substance that describes the
way the substance undergoes or resists change
to form a new substance.
 Example: copper objects turn green in air
• Most often the changes result from the reaction
of a substance with one or more other
substances.
• Sometimes energy (like heat or light) can trigger
a change (decomposition).
Chemical Property

Section 1.3
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A Chemical Property of Copper

Section 1.3
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Exercise
Classify each of the following as a physical or
chemical property.
a) A marshmallow gets black when roasting it in a
campfire.
chemical property
b) Zinc is a solid at room temperature.
physical property
c) When rubbing alcohol is rubbed on your skin, it
evaporates very quickly.
physical property

Section 1.4
Changes in Matter
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• Process in which a substance changes its
physical appearance but not its chemical
composition.
• A new substance is never formed as a result of a
physical change.
 Example: boiling or freezing water
Physical Change

Section 1.4
Changes in Matter
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• A process in which a substance undergoes a
change in chemical composition.
• Involves conversion of the material(s) into one or
more new substances.
 Example: methane reacts with oxygen to form carbon
dioxide and water
Chemical Change

Section 1.4
Changes in Matter
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Use of the Term Physical

Section 1.4
Changes in Matter
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Use of the Term Chemical

Section 1.4
Changes in Matter
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Concept Check
Which one of the following are examples of a
chemical change?
 Pulverizing (crushing) rock salt
 Burning of wood
 Dissolving of sugar in water
 Melting a popsicle on a warm summer day

Section 1.5
Pure Substances and Mixtures
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• Pure substance – a single kind of matter that
cannot be separated into other kinds of matter
by any physical means.
 Examples: water or carbon dioxide
• Mixture – a physical combination of two or more
pure substances in which each substance
retains its own chemical identity.
 Example: salt water
Pure Substances vs. Mixtures

Section 1.5
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• Have variable composition
Mixtures
Homogeneous Mixture:
Heterogeneous Mixture:
• Contains only one visibly distinct phase (part),
which has uniform properties throughout;
solution
• Contains visibly different phases (parts), each
of which has different properties

Section 1.5
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Homogeneous Mixtures

Section 1.5
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Homogeneous vs. Heterogeneous Mixtures

Section 1.5
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Section 1.5
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Concept Check
Which of the following is a homogeneous
mixture?
 Pure water
 Gasoline
 Jar of jelly beans
 Soil
 Copper metal

Section 1.6
Elements and Compounds
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• Element – a pure substance that cannot be
broken down into simpler pure substances by
chemical means such as a chemical reaction, an
electric current, heat, or a beam of light.
 Examples: gold, silver, copper
Element

Section 1.6
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• Compound – a pure substance that can be
broken down into two or more simpler pure
substances by chemical means.
 Examples: water, carbon dioxide, ammonia
Compound

Section 1.6
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A Pure Substance Can Be Either An Element or Compound

Section 1.6
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Compound vs. Mixture

Section 1.6
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1) Compounds have properties distinctly different
from those of the substances that combined to
form the compound. The components of
mixtures retain their individual properties.
Distinguishing Between Compounds and Mixtures

Section 1.6
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2) Compounds have a definite composition.
Mixtures have a variable composition.

Section 1.6
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3) Physical methods are sufficient to separate the
components of a mixture. The components of a
compound cannot be separated by physical
methods; chemical methods are required.

Section 1.6
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1) Does the sample of matter have the same
properties throughout?
2) Are two or more different substances present?
3) Can the pure substance be broken down into
simpler substances?
To Classify a Sample of Matter

Section 1.7
Discovery and Abundance of the Elements
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• 117 known elements:
 88 of the elements occur naturally
 29 of the elements have been synthesized

Section 1.7
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Abundance of Elements (in Atom Percent) in the Universe

Section 1.7
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Abundance of Elements (in Atom Percent) in the Earth’s Crust

Section 1.7
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Elemental Composition of the Human Body (in Atom Percent)

Section 1.8
Names and Chemical Symbols of the Elements
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• One- or two-letter designation for an element
derived from the element’s name.
• Two letter symbols are often, but not always, the
first two letters of the element’s name.
Chemical Symbol

Section 1.8
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• First letter of a chemical symbol is always
capitalized and the second is not:
 H – hydrogen
 Ba – barium
 Co – cobalt
 Pb – lead
 Ag – silver
Chemical Symbol

Section 1.8
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• For some elements, the symbol is derived from
the Latin name of the element:
 Ag – silver
 Au – gold
 Fe – iron
 Pb – lead
 Cu – copper
Latin Names

Section 1.9
Atoms and Molecules
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• The smallest particle of an element that can
exist and still have the properties of the element.
• The limit of chemical subdivision.
• Atoms are extremely small particles.
Atom

Section 1.9
Atoms and Molecules
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• Group of two or more atoms that functions as a
unit because the atoms are tightly bound
together.
• The limit of physical subdivision.
• Behaves in many ways as a single, distinct
particle would.
• Diatomic molecule – contains two atoms
• Triatomic molecule – contains three atoms
• Tetraatomic, pentatomic, etc.
Molecule

Section 1.9
Atoms and Molecules
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• Molecule in which all atoms present are of the
same kind.
• Substance containing homoatomic molecules
must be an element.
 Examples: H2, O2, N2, Cl2, P4, S8
Homoatomic Molecule

Section 1.9
Atoms and Molecules
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Homoatomic Molecules

Section 1.9
Atoms and Molecules
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• Molecule in which two or more kinds of atoms
are present.
• Substance containing heteroatomic molecules
must be compounds.
 Examples: H2O, CO2, N2O4, C12H22O11
Heteroatomic Molecule

Section 1.9
Atoms and Molecules
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Heteroatomic Molecules

Section 1.9
Atoms and Molecules
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Concept Check
Classify XeF4 as:
1)diatomic, triatomic, etc.
pentatomic
2)homoatomic or heteroatomic
heteroatomic
3)element or compound
compound

Section 1.10
Chemical Formulas
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• A notation made up of the chemical symbols of
the elements present in a compound and
numerical subscripts (located to the right of each
chemical symbol) that indicate the number of
atoms of each element present in a molecule of
the compound.
 Examples:
 H2O – two atoms of hydrogen, one atom of oxygen
 Ca3(PO4)2 – three atoms of calcium, two atoms of
phosphorus, eight atoms of oxygen

Section 1.10
Chemical Formulas
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Exercise
For each of the following chemical formulas,
determine how many atoms of each element
are present:
a) H2SO4
two hydrogen; one sulfur; four oxygen
b) Fe2(CO3)3
two iron; three carbon; nine oxygen

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