SOLIDS
Properties
 Solid
particles have fixed positions
 Particles
are very close together
 Solids
have fixed shapes and fixed
volumes
 Usually
exist in crystalline form
Solid Crystals
 Can
be very brittle, like salt
 Can
be very soft, like lead
Changing States
Deposition (Frost forming)
◦ Molecules in the gaseous state become part
of the surface of a crystal
 Sublimation
◦ Process in which a solid changes directly into
a gas
◦ Exothermic process

◦ Energy released in decomposition is equal to
the energy required for sublimation
Freezing
◦ Change in state in which a liquid becomes a
solid as heat is removed
◦ Exothermic process releases energy
 Melting
◦ The change in state in which a solid becomes
a liquid by adding or changing pressure

◦ Melting point and Freezing point are the same
for pure substances
LIQUIDS

Particles can move easily past each other

Are fluids

Have fixed volumes, but take the shape of the
container placed in
Liquid Forces

Cohesion
◦ Attraction for each other
 Water molecules stick each other

Adhesion
◦ Attraction for particles of solid surfaces
 Water molecules do not stick to car wax
Combine the two and get capillary action
Surface Tension

Force that acts on the surface of a liquid
and that tends to minimize the area of the
surface

Liquids tend to decrease their surface
area to the smallest possible size

Why liquids for spherical shapes (Drops),
smallest surface area for a volume
Changing States

Condensation
◦ Gas becomes a liquid

Evaporation
◦ Liquid becomes a gas
◦ Endothermic process
◦ Boiling Point- temperature and pressure when
a liquid and gas are at equilibrium