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Chapter 3
Matter Properties and Changes
• Atom: The smallest particle of an element
that retains all the properties of that element
– Comprised of protons, neutrons and electrons
• Element: A pure substance that can’t be
broken down by physical or chemical means.
– An atom of any element always has the same
number of protons.
Properties and Changes
• Substance: Matter that has a uniform
unchanging composition
– Also known as a pure substance
– Ex: water, only composed of two different
substances, and can not be separated by
physical means.
• Mixture:Two or more substances
combined having variable composition
– Ex: salt water, contains two substances, and
can be separated by physical means.
Types of Substances
• Compounds
– Can be separated by
chemical means
– Composed of two or
more different
elements in distinct
whole number ratios
– Ex: Water, H2O
– Ex: Salt, NaCl
• Elements
– Elements can not be
separated by chemical
means
– Ex: Gold, Au
– Carbon, C
Types of Mixtures
• Homogeneous
– A mixture with no
physically distinct
parts in the solution.
– Ex: Salt water
– Ex: air
• Heterogeneous
– A mixture with distinct
physical boundaries.
– Ex: granite
– Ex: orange juice
Changes
• Physical Change: Change that does not
alter the chemical composition of the
substance.
– Ex: Melting ice
• Chemical Change: One or more substances
are changed into other substances
– Ex: chemical reaction
Physical Properties
• Properties that do not involve or describe
a substance changing into another
substance
• Or, a characteristic that can be observed
or measured without changing the
sample’s composition.
• Ex: Melting Point, Boiling Point, Hardness,
and Luster
Physical Properties
• Extensive Properties: Depends on the
mass of a substance
– Ex: Mass, Length, Volume
• Intensive Properties: Does not depend on
the amount of the substance present
– Ex: Density, Solubility
Chemical Properties
• The ability of a substance to combine with
or change into one or more other
substances.
– Ex: Iron reacts readily with the oxygen in the
air to form iron oxide (rust).