Chem 200
Dr. Saidane
Lecture Notes
Chap 1, Part 1
Matter and Changes

Chemistry is the study of matter and the changes it can undergo.
Chemistry deals with questions such as:
1. What is that material made of?
2. What is its makeup and internal arrangement?
3. How does it behave and change when heated, cooled, or mixed with other
materials?
4. Why does this behavior occur?

Matter is anything that has mass and takes up space.
Matter appears in a huge variety of forms. It includes anything we can touch or see as
well as anything we cannot touch or see. Therefore the knowledge of chemistry is
essential if we want to understand how the world works.
Matter is made of atoms, elements, and compounds. It has different states, properties and
undergoes changes.
 Building Blocks of Matter:
1. An atom is the building block of matter. It is the smallest unit of an element that
maintains the properties of that element.
2. An ion is a positively or negatively charged atom or group of atoms.
3. An element is a pure substance made of only one kind of atom.
4. A compound is a substance that is made from the atoms of two or more elements
that are chemically bonded. They are classified as either molecular compounds or
ionic compounds.
5. A molecule or a molecular compound is a definite and distinct electrically
neutral group of bonded atoms.
6. An ionic compound is a definite and distinct electrically neutral group of bonded
ions.
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 States of Matter
Matter can be gas, liquid, or solid.
1.
Matter in the gas state has neither definite volume nor definite shape. It takes the
volume and shape of container. The particles are far apart from each other and
move in strait lines freely, randomly and rapidly inside the container.
2. Matter in the liquid state has a distinct volume independent of the container. It
has no specific shape. The particles are close to each other. They move around
but not as fast as in the gas state.
3. Matter in a solid state has definite volume and definite shape. The particles are
packed in a definite, ordered arrangement. They can only rotate and vibrate in a
fixed position.
 Properties of Matter
Properties of matter allow chemists to distinguish between substances and to separate
them.
A property is a characteristic that defines an entire group or subgroup of
substances such as electric conductivity. Comparisons of several properties can be used
together to establish the identity of an unknown.
There are two ways of grouping properties of substances:
1.
Properties are either intensive or extensive.
2.
Properties are either physical or chemical.
1. a) Extensive properties depend on the amount of matter that is present. Such
properties include volume, mass, and the amount of energy in a substance.
b) Intensive properties do not depend on the amount of matter present. Such
properties include the melting point, boiling point, density, and the ability to
conduct heat or electricity.
2. a) A physical property is a characteristic that can be observed or measured
without changing the identity of a substance. Such properties are color, melting
point, boiling point, mass, and volume.
b) A chemical property relates to a substance’s ability to undergo changes that
transform it into different substances. For example the ability of charcoal to burn
in air is a chemical property.
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 Changes in Matter
Matter can undergo physical or chemical changes.
1. A physical change is a change in a substance that does not involve a change
in the identity of the substance.
Such physical changes include cutting,
melting, grinding, and boiling a substance.
2. A chemical change is a change in which one or more substances are
converted into different substances.
A chemical change is also called a
chemical reaction. Such chemical changes are the burning of charcoal, the
corrosion of an iron bar, and the baking of bread.
The substances that react in a chemical change are called reactants. The substances that
are formed in a chemical change are called products.
 Classification of Matter
Matter can be classified in terms of uniformity of composition and properties of a given
sample into one of two groups: pure substances or mixtures.
1.
A pure substance is made of one kind of matter. A pure substance can be an
element or compound.
a)
Every sample of a given pure substance has exactly the same
characteristic physical and chemical properties. These properties are so
specific that they can be used to identify the substance.
b) The composition of a pure substance is the same throughout and does not
vary from sample to sample. This characteristic is also known as the law
of constant composition or the law of definite proportions. For example,
pure water is always 11.2% hydrogen and 88.8% oxygen by mass.
2. A mixture is a blend of two or more kinds of matter each of which retains its own
identity and properties. It is a form of matter that can be separated by making use of
the physical properties of the components.
a) The properties of a mixture depend on the relative amounts of the
mixture’s components.
b) Mixtures are made of various amounts of different substances of different
compositions.
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Based on the uniformity of their compositions, mixtures can be classified as
homogeneous or heterogeneous.
A homogeneous mixture, also called solution, has a uniform composition. This means
that it has the same proportion of components throughout. A salt-water solution is an
example of such mixtures.
A heterogeneous mixture has a non-uniform composition. It has different proportions
of components throughout. An oil and water mixture is an example of heterogeneous
mixture.
 Separation of Mixtures
Mixtures are separated by making use of the differences in physical properties of the
components. Techniques include filtration, distillation, and chromatography.
1.
Filtration makes use of the differences in solubility (the ability to dissolve in a
liquid). The soluble material dissolves in the liquid and passes through the
filter. The insoluble material does not dissolve and is captured by the filter.
This technique can be used to separate sugar from sand.
2.
Distillation makes use of differences in boiling points. Distillation separates the
components of a mixture by vaporizing one or more of the components. It can
be used to remove water from salt, or remove alcohol from water.
3.
Chromatography relies on the different abilities of substances to stick to
surfaces. The mixture is separated as it travels through a surface carried by a
fluid substance. Some molecules are adsorbed more readily than other and
therefore emerge later with the carrier. This technique is the most sensitive. It
allows separating, as well as identifying the different components of a mixture.
 Skills you should have mastered
Conceptual
1. Define chemistry.
2. Define matter.
3. Distinguish atoms, ions, elements, compounds, and molecules.
4. Give the name of elements given their symbol and vice versa.
5. Distinguish physical properties and chemical properties.
6. Distinguish intensive properties and extensive properties.
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7. Identify physical and chemical changes.
8. Distinguish mixtures, and pure substances.
9. Define the law of constant composition.
10. Distinguish homogeneous and heterogeneous mixture.
Descriptive
1. Describe how matter is classified.
2. Describe the difference between gas, liquid, and solid state.
3. Describe how mixtures are separated.
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Differences between mixtures and compounds
Mixture
Compound
 Components can be separated by using
 Components cannot be separated by
physical techniques
using physical techniques
 Composition is variable
 Composition is fixed
 Properties are related to those of its
 Properties are unlike those of its
components
components
Differences between a pure substance and a mixture
Pure Substance
Mixture
 Every substance has the same physical
 Properties depend on relative amounts
and chemical properties
of different substances in mixture
 Uniform composition throughout the
 Different
sample
composition
for
each
various
amounts
substance
 Constant composition from sample to
 May
sample
have
of
substances in each sample
Differences between the three states of matter
Gas
 No definite volume
 No definite shape. Takes
shape of container
 Particles far apart from
each other
 Particles move around in
strait lines, freely,
Liquid
Solid
 Definite volume
 Definite volume
independent of container
 Definite shape
 No definite shape. Takes  Particles packed in a
shape of container
definite ordered
 Particles are close to
 Particles
each other
 Particles move around in
randomly, and rapidly
strait
inside the container
randomly,
arrangement
lines,
and
can’t
move
around freely, in strait
freely,
lines. They can only
slowly
rotate and vibrate in a
inside the container
fixed position.
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