Describing Matter and Its Changes
Ms. Grobsky
Physical Properties
 Physical properties can be observed WITHOUT changing the
composition of the substance
 Directly observable
 Substance DOES NOT become another substance
 Examples
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Odor
Color
Volume
Physical state
Density
Melting point
Boiling point
Solubility
Viscosity
Chemical Properties
 Chemical properties can ONLY be observed during a chemical
reaction
 Also defined as the characteristics that determine how the composition of
matter changes as a result of contact with other matter or the influence of
energy
 Describes ability of a substance to change to a different
substance
 Example
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Chemical reactivity
Oxidizer
Flammability
pH
Electrical conductivity
Changes in Matter – Physical Changes
 Physical changes alter the state or appearance of matter
without altering the composition
 Starting material stays the same
 Physical changes are changes in physical properties
 Most common are changes of state (solid, liquid, gas)
 Dissolving a solid in water
Physical Changes in Matter
• The boiling of
water is a physical
change
• The water
molecules are
separated from
each other, but
their structure
and composition
do not change
Common Physical Changes
Subliming of Dry Ice
Dissolving of Sugar
Changes in Matter – Chemical
Changes
 Defined as changes that alter the composition of matter
 Products are different than starting material
 Also called chemical reactions
 During the chemical change, the atoms that are present
rearrange into new molecules, but all of the original atoms
are still present
 Examples
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Rusting
Tarnishing
Processes that release lots of energy
Burning
Chemical Changes in Matter
• The rusting of iron
is a chemical change
• The iron atoms in
the nail combine
with oxygen atoms
from O2 in the air to
make a new
substance, rust, with
a different
composition
Common Chemical Changes
 Combustion (burning) of
propane gas (C3H8)
produces carbon dioxide
and water
 Products are different than
starting material