Classification of Matter
Mixtures, elements, compounds
Scientists like to classify things.
 One way that scientists classify matter is
by its composition.
 Ultimately, all matter can be classified as
mixtures, elements and compounds.

Why isn’t it a good idea to classify
matter by its phases?

Because one kind of substance can exist in
more than one phase – such as H20. And matter
changes phases rather easily.
Why isn’t matter classified according to
its physical characteristics, such as color?

Scientists wouldn’t find it very useful to group
gold, sunflowers, and the sun together.
Composition of Matter Flowchart
MATTER
yes
MIXTURE
yes
Is the composition
uniform?
Homogeneous
Mixture
(solution)
no
Can it be physically
separated?
PURE SUBSTANCE
no
Heterogeneous
Mixture
yes
Can it be chemically
decomposed?
Compound
no
Element
Classifying Matter by Composition
Mixtures- are a blend of two or more
kinds of matter, each of which retains its
own identity and properties.
 A mixture is mixed together physically.
 Variable composition, often expressed
by a percent composition by mass or
volume (Ex. 5% salt and 95% water
Classifying Matter by Composition
1.
2.
Homogeneous – matter with a
uniform composition. They are
also called solutions. Ex. Salt
water and Kool –aid
Heterogeneous - matter without
a uniform composition
Homogeneous Mixtures
A mixture that appears to be the same
throughout.
 It is “well mixed.”
 The particles that make up the mixture
are very small and not easily
recognizable.

Examples of homogeneous mixtures
Milk, toothpaste, and mayonnaise are homogeneous
mixtures. They are also colloids.
Colloids
100
80
60
East
40
20
0
West
North
1st 2nd 3rd 4th
Qtr Qtr Qtr Qtr
In a colloid the
particles are mixed
together but not
dissolved.
 The particles are
relatively large and
are kept permanently
suspended.

Colloids
A colloid will not
separate upon
standing.
 The particles are
constantly colliding,
and this allows a
colloid to scatter light
– thus colloids often
seem cloudy.

Solutions
A solution is a type of homogeneous
mixture formed when one substance
dissolves in another.
 It is the best mixed of all mixtures.
 A solution always has a substance that is
dissolved and a substance that does the
dissolving.
 The substance that is dissolved is the
solute and the substance that does the
dissolving is the solvent.

Ocean water is a solution
Water as a solvent
Many liquid solutions contain water as
the solvent.
 Ocean water is basically a water
solution that contains many salts.
 Body fluids are also water solutions.

Types of solutions
Solute
Solvent
Example
Gas
Gas
Gas
Liquid
Solid
Liquid
Air (oxygen in nitrogen)
Soda water (carbon dioxide in
water)
Ocean water (salt in water)
Solid
Solid
Gold jewelry (copper in gold)
Metals dissolved in
metals are called
alloys.
Air is a solution of oxygen and other
gases dissolved in nitrogen
Alloys
Stainless steel is a mixture
of iron and chromium.
Brass is an alloy of copper
and zinc.
Classifying Matter by Composition

A heterogeneous mixture is not
the same throughout (not
uniform).
 Considered the “least mixed.”
 Does not appear to be the same throughout.
 Particles are large enough to be seen and to
be separated from the mixture.
Examples of heterogeneous mixtures
Sand and pebbles, gravel, soil, rocks
 Oil and water, salad,


M & M’s, Chocolate cookies.
Granite is a heterogeneous mixture.
Separating Mixtures
Mixtures are separated by their
physical properties.
Primary methods of separating
mixtures are:
filtration
distillation
centrifuge
chromatography
Separating Mixtures
Filtration
is a method used
to separate the
components of mixtures
that contain an insoluble
solid and a liquid.
Example: sand and water
Separating Mixtures
Distillation
is a method of
separating substances in a
mixture by evaporation of a
liquid and subsequent
condensation of its vapor.
Example: desalination of
salt water
Separating Mixtures
 Centrifuge
 Used
to separate solid-liquid
mixtures such as those in
blood. The centrifuge spins
rapidly and causes the solid
to settle to the bottom.
 Ex. Separating blood
Separating Mixtures
Chromatography is a method of
separating mixtures that uses a
stationary phase and a mobile
phase. Paper chromatography
can be used to separate
pigments because they move
at different rates on the paper.
Composition of Matter Flowchart
MATTER
yes
MIXTURE
yes
Is the composition
uniform?
Homogeneous
Mixture
(solution)
no
Can it be physically
separated?
PURE SUBSTANCE
no
Heterogeneous
Mixture
yes
Can it be chemically
decomposed?
Compound
no
Element
Classifying Matter by Composition
Pure Substances- A pure type of matter
that does not vary from sample to sample.
Includes elements and compounds
Classifying Matter by Composition
1-Elements- simplest kind of matter, made of
one type of atom
 An atom is the smallest unit of an element
that maintains the properties of that
element.
 Cannot be broken down into simpler
substances by ordinary chemical means
 Ex. gold, copper, oxygen (on the periodic
table)
Classifying Matter by Composition
2-Compounds – matter composed of the
atoms of two or more elements chemically
bonded
 Compounds can be broken down by
chemical methods
 When they are broken down, the
components have completely different
properties than the compound.
 Ex. Sugar, salt, water, carbon dioxide
Compounds
Compounds are also
pure substances.
 But compounds are
made from more than
one element.
 Water is a
compound.
 Water can be broken
down into simpler
substances –
hydrogen and
oxygen.

Classify It
copper wire, aluminum foil
Classify It

Examples:
 Magnesium-
element
 Pizza -
hetero. mixture
 Calcium chloride compound
 Orange juice
hetero. mixture
 Club soda
Homo. (solution)
States of matter
Solid- matter that can not flow and has
definite volume and shape
 Liquid- definite volume but no definite
shape and can flow
 Gas- a substance without definite
volume or shape and can flow.
 Plasma- a substance that is similar to a
gas, but loses electrons due to its high
temperature

States of Matter
Definite Definite Particle position
Volume? Shape? and movement
Solid
Liquid
Gas
YES
YES
NO
YES
Packed tightly,
vibrate about fixed pt
NO
Close together, can
move past each
other - flow
NO
Far apart, move
rapidly - flow