Chemistry ch 14B SLG

 Solid
particles have fixed positions
 Particles
are very close together
 Solids
have fixed shapes and fixed
 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
◦ 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
Particles can move easily past each other
Are fluids
Have fixed volumes, but take the shape of the
container placed in
Liquid Forces
◦ Attraction for each other
 Water molecules stick each other
◦ 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
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
◦ Gas becomes a liquid
◦ Liquid becomes a gas
◦ Endothermic process
◦ Boiling Point- temperature and pressure when
a liquid and gas are at equilibrium