Properties of Matter
2.1 Classifying Matter
Section 2.1: Classifying
Matter
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.
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Section 2.1: Classifying
Matter
Pure Substances
 What is Matter? Anything that has mass and
takes up space (volume)
 Based on matter’s composition, it can be
divided into Pure Substances and Mixtures.
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Matter Flowchart
MATTER
yes
MIXTURE
yes
Is the composition
uniform?
Homogeneous
Mixture
(solution)
no
Can it be separated by
physical means?
PURE SUBSTANCE
no
Heterogeneous
Mixture
yes
Can it be decomposed
by chemical means?
Compound
no
Element
Section 2.1: Classifying
Matter
Pure Substances
Def.-matter that always has exactly the same
composition (ex. Table salt, table sugar)
Key Concept: Every sample of a given substance
has the same properties because a substance has
a fixed, uniform composition.
2 Categories of substances: elements and
compounds
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Section 2.1: Classifying
Matter
Elements
 Def.-a substance that cannot be broken
down into simpler substances
 Key Concept: An element has a fixed
composition because it contains only one
type of atom.

Section 2.1: Classifying
Matter
Elements: Examples of Elements
 Carbon (C), Aluminum (Al)- solid at RT
 Oxygen (O), Nitrogen (N)- gases at RT
 Bromine (Br), Mercury (Hg)- liquid at RT
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Section 2.1: Classifying
Matter
Elements: Symbols for Elements
 Developed in 1813 by Swedish chemist Jons
Berzelius
 Symbols contain 1 or 2 letters
 Symbols based on Latin names of the
elements
 Gold is Au
 Aluminum is Al
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Section 2.1: Classifying
Matter
Compounds
 Def.-a substance that is made from two or
more simpler substances and can be broken
down into those simpler substances
(elements or other compounds)
 H2O→2H + O
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Section 2.1: Classifying
Matter
Compounds
 Properties of a compound differ from the
properties of the substances from which it is
made.
 Ex. H and O are gases at room temp.; H2O
is liquid at room temp.
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Section 2.1: Classifying
Matter
Compounds
 Key Concept: A compound always
contains two or more elements
joined in a fixed proportion.
 Ex. SiO2- 2 (O) atoms for every 1 (Si) atom
 Ex. H2O-2 (H) atoms for every 1 (O) atom
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Section 2.1: Classifying
Matter
Mixtures
 2 types: heterogeneous and homogeneous
 Retain some of the properties of their
individual substances
 Properties of a mixture are less constant
(vary) than the properties of a substance.

Section 2.1: Classifying
Matter
Mixtures
 Key Concept: The properties of a mixture
can vary because the composition of a
mixture is not fixed.
 **Mixtures can be classified by how well the
parts of the mixture are distributed
throughout the mixture.
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Section 2.1 Classifying
Matter
Mixtures: Heterogeneous and
Homogeneous Mixtures
 Heterogeneous- the parts of the mixture are
noticeably different from one another
 Ex. Sand
 Homogeneous-the substances are so evenly
distributed that it is difficult to distinguish one
substance in the mixture from another
 Ex. Water, steel
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Section 2.1 Classifying
Matter
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Is the mixture uniform throughout?

If the answer is NO, the matter is a
heterogeneous mixture.
 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.
Section 2.1 Classifying
Matter
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Is the mixture uniform throughout?
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If the answer is YES, the matter is a
Homogenous mixture.
Matter Flowchart
MATTER
yes
MIXTURE
yes
Is the composition
uniform?
Homogeneous
Mixture
(solution)
no
Can it be separated by
physical means?
PURE SUBSTANCE
no
Heterogeneous
Mixture
yes
Can it be decomposed
by chemical means?
Compound
no
Element
Section 2.1 Classifying
Matter
Solutions, Suspensions, and Colloids
 The size of the particles in a mixture has an
effect on the properties of the mixture.
 Key Concept: Based on the size of its
largest particles, a mixture can be classified
as a solution, a suspension, or a colloid.
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Section 2.1 Classifying
Matter
Solutions
 Def.-the mixture that forms when substances
dissolve and form a homogeneous mixture
 Ex. Sugar water, salt water,
lemonade
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Section 2.1 Classifying
Matter
Solutions
*They do not separate into distinct layers
over time.
*They cannot be filtered.
*Light passes through them.
The particles in a solution are too small to
settle out of the solution, be trapped by a
filter, or scatter light.
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Section 2.1 Classifying
Matter
Suspensions
Def.-a heterogeneous
mixture that separates
into layers over time
Ex. Amoxicillin, Muddy
water, Flour
suspended in water
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Section 2.1 Classifying
Matter
Suspensions
 *Suspended particles settle out of a mixture
or are trapped by a filter
 They scatter light in all directions because
the particles are large; suspensions are
cloudy.
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Section 2.1: Classifying
Matter
Colloids
 Def.-a mixture that contains some particles
that are intermediate in size between the
small particles in solution and larger particles
in a suspension
 Ex. Milk, fog
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Section 2.1 Classifying
Matter
Colloids
 Do not separate into layers
 Cannot be filtered
 Since they also contain larger particles, they
scatter light
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Matter Flowchart
MATTER
yes
MIXTURE
yes
Is the composition
uniform?
Homogeneous
Mixture
(solution)
no
Can it be separated by
physical means?
PURE SUBSTANCE
no
Heterogeneous
Mixture
yes
Can it be decomposed
by chemical means?
Compound
no
Element