Study Guides
Big Picture
Everything around us is made out of matter. All matter has mass and occupies space. Matter can be classified into pure
substances or mixtures. In turn, pure substances are either elements or compounds. Matter also exists in four main
states: solid, liquid, gas, and plasma. Classifying and understanding matter is important for scientists, since it enables
them to observe patterns and classify new substances as they are discovered.
Key Terms
Matter: Anything that has mass and occupies space.
Chemistry
Matter
Atom: Basic unit of matter.
Pure Substance: Material with a constant chemical composition and properties.
Element: Simplest form of matter that has a unique set of properties.
Compound: Two or more elements chemically combined in a fixed proportion.
Mixture: A combination of substances held together physically. The ratio of the substances can be changed, and each
substance within the mixture retains its original properties.
Homogeneous Mixture: A mixture with uniformly distributed particles.
Heterogeneous Mixture: A mixture with non-uniformly distributed particles.
Suspension: Large particles suspended in another substance. Eventually, they will separate out.
Colloid: Medium-sized particles mixed with another substance that will not separate out.
Solution: Small particles that are dissolved in another substance.
Property: A characteristic that can be used to describe or identify matter.
Classifying Matter
Chemistry is the study of matter and how matter behaves. Matter can be classified as pure substances or mixtures.
• A
pure substance can be an element or a compound. Compounds can be broken down into simpler substances
by chemical means, elements cannot.
• Mixtures
are formed when two or more substances are combined in some random proportion. They can be
homogeneous or heterogeneous.
• Homogeneous mixtures are often called solutions. Example: salt water
• A suspension is a type of heterogeneous mixture because particles will
eventually separate and settle out.
Examples: blood and dirt mixed with water
• A
colloid is a type of mixture where the particles don’t separate out. Can be considered as homogeneous or
heterogeneous. Example: milk
• The Tyndall effect can be used to distinguish between mixtures. A beam of light is not visible unless it is scattered
by particles.
• A beam of light is visible through suspensions – the particles are large enough to deflect light.
• A beam of light is NOT visible through a solution – the particles are too small.
Figure: Flow chart to classify matter.
Image Credit: Rory Runser, CC-BY-SA 3.0
This guide was created by Steven Lai, Rory Runser, and Jin Yu. To learn more
about the student authors, visit http://www.ck12.org/about/about-us/team/
interns.
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v1.1.12.2012
Disclaimer: this study guide was not created to replace
your textbook and is for classroom or individual use only.
Image credit
Chemistry
Matter
cont .
States of Matter
Comparing the properties of the three
major states of matter
Solid
Liquid
Gas
Have definite
shape
Have indefinite
shape
Have indefinite
shape
Has definite
volume
Has definite
volume
Has indefinite
volume
Unable to be
compressed
Unable to be
compressed
Able to be
compressed
Solid grid of
molecules
Loosely bound
molecules
Bouncing
molecules
Low energy
Medium energy
Highest energy
There is a fourth state of matter called plasma. Plasma
consists of atoms that have ionized (lost their electrons).
It has a higher energy level than gas.
Figure: Diagram of phase changes.
Image Credit: F l a n k e r, penubag
Public Domain
The arrangement of particles is different in the three
states of matter.
Image Credit: Yelod, CC-BY-SA 3.0
Figure: Visualization of the three major states of matter.
Properties of Matter
A property is an attribute that is intrinsic, or unique, to
that substance. Properties are use to describe matter,
and they can be either physical or chemical.
Physical Property
A physical property is an attribute of a substance that
can be determined without a chemical reaction. A
physical change is a change in physical property and
does not change the identity of the substance.
There are many types of physical properties.
• Freezing
Point: The temperature where a substance
will freeze/melt.
• Boiling
Point: The temperature where a substance
will boil/condense.
• Density
(ρ–Greek letter rho): Mass per volume.
Commonly measured in grams/centimeter cubed
(g/cm3).
• Conductivity:
How well a substance conducts
electricity. Metals are usually more conductive than
nonmetals are.
• Ductility:
How well a substance can be drawn into
a thin wire. Metals such as copper are very ductile.
• Brittleness:
How easily a substance will break into
smaller pieces without becoming deformed. Salt and
sugar are brittle.
• Malleability:
How easily a compound can be altered
in shape or form without breaking. Metals are
malleable, salt is not.
• Color: The color of a compound.
Since mixtures are a physical blend of two or more
components, differences in physical properties can be
used to separate mixtures.
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Chemical Property
A chemical property is an attribute of a substance that
can only be determined with a chemical reaction. A
chemical change is a change in chemical property that
changes the identity of the substance.
Some important examples of chemical properties:
• Reactivity:
How easily it reacts with another
substance. Elements in the first column of the
periodic table (called the alkali metals) are very
reactive.
• Heat
of combustion: How much energy is released
when something burns. Hydrocarbons, such as
octane (the gas in your car), have high heats of
combustion.
• Toxicity: How dangerous and hazardous a substance
is for your body.
Words like burn, rot, rust, decompose, ferment,
explode, and corrode usually suggests a chemical
change.
Intensive and Extensive Properties
Properties can be classified as extensive or intensive.
• Intensive
property: a property of a substance that
does not depend on the quantity of the substance.
All the physical and chemical properties listed
above are intensive properties. A small speck of the
substance will have the same properties as 1000
pounds of the substance.
• Extensive
property: depends on the quantity of the
substance. Mass and volume are both extensive
properties.