Topic
4
Table of Contents
Topic
4
Topic 4: Matter—Properties
and Change
Basic Concepts
Additional Concepts
Matter—Properties and Change: Basic Concepts
Topic
4
•
•
•
•
Properties of Matter—Substances
Matter that has a uniform and
unchanging composition is called
a substance, also known as a
pure substance.
Table salt is a substance.
Another example of a pure
substance is water.
Water is always composed
of hydrogen and oxygen.
Matter—Properties and Change: Basic Concepts
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4
Properties of Matter—Substances
• Seawater, on the other hand, is not a
substance because samples taken from
different locations will probably have
differing compositions.
• That is, they will contain differing amounts
of water, salts, and other dissolved
substances.
Matter—Properties and Change: Basic Concepts
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4
Physical Properties of Matter
• A physical property is a characteristic that
can be observed or measured without
changing the sample’s composition. Physical
properties describe pure substances, too.
• Because substances have uniform and
unchanging compositions, they have consistent
and unchanging physical properties as well.
Matter—Properties and Change: Basic Concepts
Topic
4
Physical Properties of Matter
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Matter—Properties and Change: Basic Concepts
Topic
4
Physical Properties of Matter
• density,
• taste,
• color,
• hardness,
• odor,
• melting point,
• and boiling point are common physical
properties that scientists record as identifying
characteristics of a substance.
Matter—Properties and Change: Basic Concepts
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Extensive and Intensive Properties
• Physical properties can be further
described as being one of two types.
• Extensive properties are
dependent upon the amount of
substance present. For example,
mass, which depends on the
amount of substance there is, is
an extensive property.
• Length and volume are also
extensive properties.
Matter—Properties and Change: Basic Concepts
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4
Extensive and Intensive Properties
• Density, on the other hand, is an example of
an intensive property of matter.
• Intensive properties are independent of the
amount of substance present.
• For example, density of a substance (at
constant temperature and pressure) is the
same no matter how much substance is
present.
Matter—Properties and Change: Basic Concepts
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4
Chemical Properties of Matter
• The ability of a substance to combine with or
change into one or more other substances is
called a chemical property.
• The ability of iron to form rust when
combined with air is an example of a
chemical property of iron
• Similarly, the inability of a substance to change
into another substance is also a chemical
property.
Matter—Properties and Change: Basic Concepts
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Chemical Properties of Matter
• For example, when iron is placed in nitrogen
gas at room temperature, no chemical change
occurs.
• The fact that iron does not undergo a change
in the presence of nitrogen is another
chemical property of iron.
Matter—Properties and Change: Basic Concepts
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Observing Properties of Matter
• Every substance has its own unique set of
physical and chemical properties.
• Observations of properties may vary
depending on the conditions of the immediate
environment.
• It is important to state the specific conditions
in which observations are made because both
chemical and physical properties depend on
temperature and pressure.
Matter—Properties and Change: Basic Concepts
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4
States of Matter
• In fact, all matter that exists on Earth can be
classified as one of these physical forms
called states of matter.
• Scientists recognize a fourth state of matter
called plasma, but it does not occur naturally
on Earth except in the form of lightning bolts.
Matter—Properties and Change: Basic Concepts
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4
States of Matter
• The physical state of a substance is a physical
property of that substance.
• Each of the three common states of matter
can be distinguished by the way it fills a
container.
Matter—Properties and Change: Basic Concepts
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4
Solids
• A solid is a form of
matter that has its
own definite shape
and volume.
• Wood, iron, paper,
and sugar are
examples of solids.
Matter—Properties and Change: Basic Concepts
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4
Solids
• The particles of matter
in a solid are very
tightly packed; when
heated, a solid expands,
but only slightly.
• Because its shape is
definite, a solid may
not conform to the
shape of the container
in which it is placed.
Matter—Properties and Change: Basic Concepts
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4
Liquids
• A liquid is a form of matter that flows, has
constant volume, and takes the shape of its
container.
• Common examples of liquids include water,
blood, and mercury.
• The particles in a liquid are not rigidly held
in place and are less closely packed than are
the particles in a solid: liquid particles are
able to move past each other.
Matter—Properties and Change: Basic Concepts
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Liquids
• This allows a
liquid to flow and
take the shape of
its container,
although it may
not completely
fill the container.
Matter—Properties and Change: Basic Concepts
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4
Liquids
• Because of the way
the particles of a
liquid are packed,
liquids are virtually
incompressible.
Like solids, liquids
tend to expand
when heated.
Matter—Properties and Change: Basic Concepts
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4
Gases
• A gas is a form of matter that flows to
conform to the shape of its container and fills
the entire volume of its container.
• Compared to solids and liquids, the particles
of gases are very far apart.
• Because of the significant amount of space
between particles, gases are easily
compressed.
Matter—Properties and Change: Basic Concepts
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4
Gases
• The word gas refers to a
substance that is naturally
in the gaseous state at room
temperature.
• The word vapor refers to
the gaseous state of a
substance that is a solid or a
liquid at room temperature.
• For example, steam is a vapor because at room
temperature water exists as a liquid.
Matter—Properties and Change: Basic Concepts
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4
Gases
• The fact that substances can change form, as
in the example of water changing to steam, is
another important concept in chemistry
• If you review what you just learned about
physical properties of substances, you can see
that because the particular form of a
substance is a physical property, changing the
form introduces or adds another physical
property to its list of characteristics.
Matter—Properties and Change: Basic Concepts
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Gases
• In fact, resources that provide tables of
physical and chemical properties of
substances, such as the CRC Handbook of
Chemistry and Physics, generally include the
physical properties of substances in all of the
states in which they can exist.
Matter—Properties and Change: Basic Concepts
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Physical Changes
• A substance often undergoes changes that
result in a dramatically different appearance
yet leave the composition of the substance
unchanged.
• An example is the crumpling of a sheet of
aluminum foil.
Matter—Properties and Change: Basic Concepts
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Physical Changes
• While the foil goes from a smooth, flat,
mirrorlike sheet to a round, compact ball, the
actual composition of the foil is unchanged—
it is still aluminum
• Changes such as this, which alter a substance
without changing its composition, are known
as physical changes.
Matter—Properties and Change: Basic Concepts
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Physical Changes
• As with other physical properties, the state
of matter depends on the temperature and
pressure of the surroundings.
• As temperature and
pressure change, most
substances undergo a
change from one state
(or phase) to another.
Matter—Properties and Change: Basic Concepts
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4
Physical Changes
• Melting and formation of a gas are both
physical changes and phase changes.
• When you encounter
terms such as boil,
freeze, condense,
vaporize, or melt in
your study of chemistry,
the meaning generally
refers to a phase change
in matter.
Matter—Properties and Change: Basic Concepts
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Chemical Changes
• Chemical properties relate to the ability of a
substance to combine with or change into one
or more substances.
• A process that involves one or more
substances changing into new substances is
called a chemical change, which is
commonly referred to as a chemical
reaction.
Matter—Properties and Change: Basic Concepts
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4
Chemical Changes
• The new
substances formed
in the reaction
have different
compositions and
different properties
from the
substances present
before the reaction
occurred.
Matter—Properties and Change: Basic Concepts
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4
Chemical Changes
• When a freshly exposed iron surface is left in
contact with air, it slowly changes into a new
substance, namely, the rust.
• The iron reacts
with oxygen in
the air to form a
new substance,
rust.
Matter—Properties and Change: Basic Concepts
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4
Chemical Changes
• Rust is a chemical combination of iron and
oxygen.
• In chemical
reactions, the
starting substances
are called reactants
and the new
substances that are
formed are called
products.
Matter—Properties and Change: Basic Concepts
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4
Chemical Changes
• Thus iron and oxygen are reactants and rust
is a product.
• When you encounter terms such as explode,
rust, oxidize, corrode, tarnish, ferment, burn,
or rot, the meaning generally refers to a
chemical reaction in which reactant
substances produce different product
substances.
Matter—Properties and Change: Basic Concepts
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4
Conservation of Mass
• By carefully measuring mass before and after
many chemical reactions, it was observed
that, although chemical changes occurred, the
total mass involved in the reaction remained
constant.
• The constancy of mass in chemical reactions
was observed so often that scientists assumed
the phenomenon must be true for all
reactions.
Matter—Properties and Change: Basic Concepts
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4
Conservation of Mass
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Matter—Properties and Change: Basic Concepts
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4
Conservation of Mass
• They summarized this observation in a
scientific law.
• The law of conservation of mass states that
mass is neither created nor destroyed during a
chemical reaction—it is conserved.
• This law was one of the great achievements
of eighteenth-century science.
Matter—Properties and Change: Basic Concepts
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4
Conservation of Mass
• The equation form of the law of conservation
of mass is:
Matter—Properties and Change: Basic Concepts
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4
Conservation of Mass
• Lavoisier’s experimental decomposition of
mercury(II) oxide is one proof of the law of
conservation of mass.
• Although a chemical reaction is obvious,
matter was neither created nor destroyed.
• The law of conservation of mass is one of the
most fundamental concepts of chemistry.
Basic Assessment Questions
Topic
4
Question 1
Identify each of the following as a property
of a solid, liquid, or gas. Some answers will
include more that one state of matter.
Basic Assessment Questions
Topic
4
A. flows and takes the shape of a container
B. compressible
C. made of particles held in a specific
arrangement
D. has definite volume
E. always occupies the entire space of its
container
F. has a definite volume but flows
Basic Assessment Questions
Topic
4
Answers
A. flows and takes the
shape of a container
liquid, gas
B. compressible
gas
C. made of particles
held in a specific
arrangement
solid
Basic Assessment Questions
Topic
4
Answers
D. has definite volume
solid, liquid
E. always occupies the
entire space of its
container
gas
F. has a definite volume
but flows
liquid
Basic Assessment Questions
Topic
4
Question 2
Identify each of the following as an example
of a chemical change or a physical change.
A. Moisture in the air forms beads of water
on a cold windowpane.
B. An electric current changes water into
hydrogen and oxygen.
C. Yeast cells in bread dough make carbon
dioxide an ethanol from sugar.
Basic Assessment Questions
Topic
4
Answers
A. Moisture in the air forms beads
of water on a cold windowpane.
Physical
B. An electric current changes
water into hydrogen and
oxygen.
Chemical
C. Moisture in the air forms beads
of water on a cold windowpane.
Chemical
Basic Assessment Questions
Topic
4
Question 3
A reaction between sodium hydroxide and
hydrogen chloride gas produces sodium
chloride and water. A reaction of 22.85 g of
sodium hydroxide with 20.82 g of hydrogen
chloride gives off 10.29 g of water. What
mass of sodium chloride is formed in the
reaction?
Basic Assessment Questions
Topic
4
Answer
33.38 g sodium chloride
Matter—Properties and Change: Additional Concepts
Topic
4
Additional Concepts
Matter—Properties and Change: Additional Concepts
Topic
4
Mixtures
• A mixture is a combination of two or more
pure substances in which each pure substance
retains its individual chemical properties.
• The composition of mixtures is variable, and
the number of mixtures that can be created by
combining substances is infinite.
Matter—Properties and Change: Additional Concepts
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4
Mixtures
• Although much of the focus of chemistry is
the behavior of substances, it is important to
remember that most everyday matter occurs
as mixtures.
• Substances tend naturally to mix; it is
difficult to keep things pure.
Matter—Properties and Change: Additional Concepts
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4
Mixtures
• Two mixtures,
sand and water,
and table salt and
water, are shown.
• You know water
to be a colorless
liquid.
Matter—Properties and Change: Additional Concepts
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4
Mixtures
• Sand is a grainy
solid that does not
dissolve in water.
• When sand and
water are mixed,
the two substances
are in contact, yet
each substance
retains its
properties.
Matter—Properties and Change: Additional Concepts
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4
Mixtures
• The sand and water
have not reacted.
• Just by looking at
the sand–water
mixture in beaker
A, it is easy to see
each separate
substance.
Matter—Properties and Change: Additional Concepts
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4
Mixtures
• Some mixtures, however, may not look like
mixtures at all.
• The mixture of table
salt and water in the
beaker labeled B is
colorless and
appears the same as
pure water.
• How can you determine if it is a mixture?
Matter—Properties and Change: Additional Concepts
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Mixtures
• If you were to boil
away the water,
you would see a
white residue.
That residue is the
salt. Thus, the
colorless mixture
actually contained
two separate
substances.
Matter—Properties and Change: Additional Concepts
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4
Mixtures
• The salt and the
water physically
mixed but did
not react and
were separated
by the physical
method of
boiling.
Matter—Properties and Change: Additional Concepts
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Types of Mixtures
• Mixtures themselves are classified as either
heterogeneous or homogeneous.
• A heterogeneous mixture is one that does
not blend smoothly throughout and in which
the individual substances remain distinct.
• The sand and water mixture is an example of
a heterogeneous mixture.
Matter—Properties and Change: Additional Concepts
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Types of Mixtures
• Suppose you draw a drop from the top of the
mixture using an eyedropper.
• The drop would be almost completely water.
Matter—Properties and Change: Additional Concepts
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4
Types of Mixtures
• If you draw a second drop from the bottom
of the mixture, that drop would contain
mostly sand.
• Thus the composition of the sand–water
mixture is not uniform—the substances have
not blended smoothly and the two substances
of the mixture (sand on the bottom and water
on the top) remain distinct.
Matter—Properties and Change: Additional Concepts
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Types of Mixtures
• A homogeneous mixture has constant
composition throughout; it always has a
single phase.
• Let’s examine the salt–water mixture using
the eyedropper.
• A drop of the mixture from the top of the
beaker has the same composition as a drop
from the bottom of the beaker. In fact, every
drop of the mixture contains the same relative
amounts of salt and water.
Matter—Properties and Change: Additional Concepts
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Types of Mixtures
• Homogeneous
mixtures are also
referred to as
solutions.
Matter—Properties and Change: Additional Concepts
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Types of Mixtures
• You are probably most familiar with solutions
in a liquid form,
such as cough
suppressant
medicine and
lemonade, but
solutions may
contain solids,
liquids, or gases.
Matter—Properties and Change: Additional Concepts
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Types of Mixtures
• The solid–solid solution
known as steel is called
an alloy.
• An alloy is a
homogeneous mixture of
metals, or a mixture of a
metal and a nonmetal in
which the metal
substance is the major
component.
Matter—Properties and Change: Additional Concepts
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4
Separating Mixtures
• Most matter exists naturally as mixtures.
• Because the substances in a mixture are
physically combined, the processes used to
separate a mixture are physical processes that
are based on the difference in physical
properties of the substances.
• Sometimes it is very easy to separate a
mixture; separating a mixture of pennies and
nickels is not a difficult task.
Matter—Properties and Change: Additional Concepts
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4
Separating Mixtures
• Heterogeneous mixtures composed of solids
and liquids are easily separated by filtration.
• Filtration is
a technique
that uses a
porous barrier
to separate a
solid from a
liquid.
Matter—Properties and Change: Additional Concepts
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4
Separating Mixtures
• Most homogeneous mixtures can be
separated by distillation
• Distillation is a separation technique that is
based on differences in the boiling points of
the substances involved.
Matter—Properties and Change: Additional Concepts
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4
Separating Mixtures
• When precisely controlled, distillation can
separate substances having boiling points
that differ by only a few degrees.
Matter—Properties and Change: Additional Concepts
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4
Separating Mixtures
• Crystallization is a separation technique that
results in the formation of pure solid particles
of a substance from a solution containing the
dissolved substance.
Matter—Properties and Change: Additional Concepts
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4
Separating Mixtures
• Chromatography is a technique that
separates the components of a mixture (called
the mobile phase) on the basis of the
tendency of each to travel or be drawn across
the surface of another material (called the
stationary phase).
• The separation occurs because the various
components of the ink spread through the
paper ant different rates.
Matter—Properties and Change: Additional Concepts
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4
Elements
• All matter can be broken down into a
relatively small number of basic building
blocks called elements.
• An element is a pure substance that cannot
be separated into simpler substances by
physical or chemical means.
Matter—Properties and Change: Additional Concepts
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4
Elements
• Each element
has a unique
chemical name
and symbol.
• The chemical symbol consists of one, two, or
three letters; the first letter is always
capitalized and the remaining letter(s) are
always lowercase.
Matter—Properties and Change: Additional Concepts
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4
Elements
• The names and symbols of the elements are
universally accepted by scientists in order to
make the communication of chemical
information possible.
Matter—Properties and Change: Additional Concepts
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4
Elements
• As many new elements were being
discovered in the early nineteenth century,
chemists began to see patterns of similarities
in the chemical and physical properties of
particular sets of elements.
• Several schemes for organizing the elements
on the basis of these similarities were
proposed, with varying degrees of success.
Matter—Properties and Change: Additional Concepts
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Elements
• In 1869, the Russian chemist Dmitri
Mendeleev made a significant contribution to
the effort. Mendeleev devised the chart which
organized all of the elements that were
known at the time into rows and columns
based on their similarities and their masses.
Matter—Properties and Change: Additional Concepts
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Elements
• Mendeleev’s organizational table was the
first version of what has been further
developed into the periodic table of elements.
• The periodic table organizes the elements
into a grid of horizontal rows called periods
and vertical columns called groups or
families.
• Elements in the same group have similar
chemical and physical properties.
Matter—Properties and Change: Additional Concepts
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Elements
• Elements in the same group have similar
chemical and physical properties.
• The table is called “periodic” because the
pattern of similar properties repeats as you
move from period to period.
Matter—Properties and Change: Additional Concepts
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Periodic Table
Matter—Properties and Change: Additional Concepts
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Compounds
• You know that matter is classified as pure
substances and mixtures.
• You also know that elements are pure
substances that cannot be separated into
simpler substances.
• There is yet another classification of pure
substances—compounds.
Matter—Properties and Change: Additional Concepts
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4
Compounds
• A compound is a combination of two or
more different elements that are combined
chemically.
• Most of the substances that
you are familiar with and, in
fact, much of the matter of the
universe are compounds.
• Water, table salt, table sugar,
and aspirin are examples of
common compounds.
Matter—Properties and Change: Additional Concepts
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4
Compounds
• Today, there are approximately 10 million
known compounds, and new compounds
continue to be developed and discovered at
the rate of about 100 000 per year.
Matter—Properties and Change: Additional Concepts
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Compounds
• There appears to be no limit to the number of
compounds that can be made or that will be
discovered.
• Considering this virtually limitless potential,
several organizations have assumed the task
of collecting data and indexing the known
chemical compounds.
Matter—Properties and Change: Additional Concepts
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4
Compounds
• These organizations maintain huge databases
that allow researchers to access information
on existing compounds.
• The databases and retrieval tools enable
scientists to build the body of chemical
knowledge in an efficient manner.
Matter—Properties and Change: Additional Concepts
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Categories of Matter
Matter—Properties and Change: Additional Concepts
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Compounds
• The chemical symbols of the periodic table
make it easy to write the formulas for
chemical compounds.
• For example, table salt, or sodium chloride, is
composed of one part sodium (Na) and one
part chlorine (Cl), and its chemical formula is
NaCl.
• Water is composed of two parts hydrogen (H)
to one part oxygen (O), and its formula is
H2O.
Matter—Properties and Change: Additional Concepts
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4
Compounds
• Unlike elements, compounds can be broken
down into simpler substances by chemical
means.
• In general, compounds that naturally occur
are more stable than the individual
component elements.
• To separate a compound into its elements
often requires external energy such as heat or
electricity.
Matter—Properties and Change: Additional Concepts
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4
Compounds
• The properties of a compound are different
from those of its component elements. The
example of water illustrates this fact.
• Water is a stable compound that is liquid at
room temperature.
Matter—Properties and Change: Additional Concepts
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4
Compounds
• When water is broken down into its
components, it is obvious that hydrogen and
oxygen are dramatically different than the
liquid they form when combined.
• Oxygen and hydrogen are tasteless, odorless
gases that vigorously undergo chemical
reactions with many elements.
Matter—Properties and Change: Additional Concepts
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4
Law of Definite Proportions
• An important characteristic of compounds is
that the elements comprising them combine
in definite proportions by mass.
• This observation is so fundamental that it is
summarized as the law of definite
proportions.
• This law states that, regardless of the amount,
a compound is always composed of the same
elements in the same proportion by mass.
Matter—Properties and Change: Additional Concepts
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4
Law of Definite Proportions
• The mass of the compound is equal to the
sum of the masses of the elements that make
up the compound.
• The ratio of the mass of each element to the
total mass of the compound is a percentage
called the percent by mass.
Matter—Properties and Change: Additional Concepts
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4
Law of Multiple Proportions
• The law of multiple proportions states that
when different compounds are formed by a
combination of the same elements, different
masses of one element combine with the
same relative mass of the other element in a
ratio of small whole numbers.
• Ratios compare the relative amounts of any
items or substances.
Matter—Properties and Change: Additional Concepts
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Law of Multiple Proportions
• The comparison can be expressed using
numbers separated by a colon or as a fraction.
• With regard to the law of multiple
proportions, ratios express the relationship of
elements in a compound.
Matter—Properties and Change: Additional Concepts
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4
Law of Multiple Proportions
• The two distinct compounds water (H2O) and
hydrogen peroxide (H2O2) illustrate the law
of multiple proportions.
• Each compound contains the same elements
(hydrogen and oxygen).
• Water is composed of two parts hydrogen
(the element that is present in different
amounts in both compounds).
Matter—Properties and Change: Additional Concepts
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4
Law of Multiple Proportions
• Hydrogen peroxide is composed of two parts
hydrogen and two parts oxygen.
• Hydrogen peroxide differs from water in that
it has twice as much oxygen.
• When we compare the mass of oxygen in
hydrogen peroxide to the mass of oxygen in
water, we get the ratio 2:1.
Matter—Properties and Change: Additional Concepts
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4
Law of Multiple Proportions
• Considering that there is a finite number of
elements that exist today and an
exponentially greater number of compounds
that are composed of these elements under
various conditions, it becomes clear how
important the law of multiple proportions is
in chemistry.
Additional Assessment Questions
Topic
4
Question 1
Identify each of the following as an example of
a homogeneous mixture or a heterogeneous
mixture.
Additional Assessment Questions
Topic
4
A. 70% isopropyl rubbing alcohol
B. a pile of rusty iron filings
C. concrete
D. saltwater
E. gasoline
F. bread
Additional Assessment Questions
Topic
4
Answers
A. 70% isopropyl rubbing
alcohol
homogeneous
B. a pile of rusty iron filings
heterogeneous
C. concrete
heterogeneous
D. saltwater
homogeneous
E. gasoline
homogeneous
F. bread
heterogeneous
Additional Assessment Questions
Topic
4
Question 2
Identify each of the following as an example of
an element or a compound.
A. sucrose (table sugar)
B. the helium in a balloon
C. baking soda
D. a diamond
Additional Assessment Questions
Topic
4
Answers
A. sucrose (table sugar)
compound
B. the helium in a balloon
element
C. baking soda
compound
D. a diamond
element
Additional Assessment Questions
Topic
4
Question 3
A 134.50-g sample of aspirin is made up of
6.03 g of hydrogen, 80.70 g of carbon, and
47.77 g of oxygen. What is the percent by
mass of each element in aspirin?
Additional Assessment Questions
Topic
4
Answer
4.48% hydrogen, 60% carbon, 35.52% oxygen
Additional Assessment Questions
Topic
4
Question 4
A 2.89-g sample of sulfur reacts with 5.72 g of
copper to form a black compound. What is the
percentage composition of the compound?
Additional Assessment Questions
Topic
4
Answer
33.6% sulfur, 66.4% copper
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