 Physical
Property- a property that can
be observed and measured without
changing the identity of the substance.
 Examples- Viscosity, density, meltingpoint
 Chemical Property-relates to a
substance’s ability to undergo changes
that transform it into different substances.
 Example-Alkali metals are highly
reactive to water and halogens to form
ionic compounds
 Chemists
use properties to identify and
separate matter. More than one property
must be used for identification.
 Intensive Properties – do not depend
on the amount of matter present
Ex. Melting pt., boiling pt, density,
conduct electricity
 Extensive Properties – depend on the
amount of matter present
Ex. Volume, mass
A
physical change does not
change the composition or
identity of the substance.
Examples?
Boiled water is still water.
All phase changes are physical
changes
Condens
e
Freeze
Evaporat
e
Mel
t
Solid
Liquid
Gas
 Sublimation
is a process in which a solid
changes directly to a gas without going
through the solid phase.
 Examples: dry ice  CO2
A
chemical change occurs when
one or more substances are changed
into new substances.
Reactants- substances that react
Products- substances that form
Products have NEW PROPERTIES
Indications of chemical change
1.) Production of heat, light, sound,
or electricity
2.) Production of a gas
3.) Formation of a precipitate
4.) A change in color
5.) A change in odor
Energy Changes
• Some changes in matter release energy.
• For example, the explosion that occurs
when hydrogen and oxygen react to form
water is a release of energy.
• Heat energy and light energy are released
as the reaction takes place.
Energy Changes
• A change in matter in which energy is absorbed from
the surroundings is an endothermic process (heat
enters).
• EXAMPLES: melting ice & boiling water
• When barium hydroxide reacts ammonium nitrate
are mixed the test-tube feels cold to touch because
energy has been absorbed
Energy Changes
• A change in matter in which energy is
released is an exothermic process (heat
exits).
• Examples: freezing water & condensation
• Burning of paper gives off heat to the
surroundings.