PARTICLE THEORY
• All matter is made up of very small particles.
• All particles in a pure substance are the same.
• There is space between the particles.
• The particles are always moving.
• The particles in a substance are attracted to each
other. The strength of the attraction depends upon
the type of particle.
Gases
- Particles not in any organized
pattern
- Particles move freely and very
quickly
- Can be compressed
- Takes up space and has weight
- Try's to take up all of the space
available in container
Liquids
- Molecules not in a fixed order or
location
- Molecules move freely, but slowly
- Cannot be compressed easily
- Can Flow
- Takes the shape of the container it
is poured into
Liquids and Cohesion
- Molecules in matter are attracted
to each other.
- Solid state has the highest level of
cohesion.
- In a liquid state molecules want to
be attached to each other. This is
why we see water droplets trying
to remain together.
Solid
- Particles in a fixed order and
location
- Particles can only move in their
fixed location (they vibrate)
- Cannot be compressed
- Cannot flow
Phase Changes of Matter
Water Phase Change Graph
E
D
100
Temperature º C.
gas
C
liquid
B
0
A
solid
Time (minutes)
E
D
100
Temperature º C.
gas
C
liquid
B
0
A
solid
Time (minutes)
E
D
condensing
100
Temperature º C.
evaporating
C
B
freezing
0
melting
A
Time (minutes)
Changes of State (Phase Changes) –
When matter changes from one state of matter
to another.
•
•
•
•
•
•
Melting (Solid to Liquid)
Condensation (Gas to Liquid)
Freezing (Liquid to Solid)
Vaporization (Liquid to Gas)
Sublimation (Solid to Gas) *Dry Ice-Solid CO2
Deposition (Gas to Solid) *Water Vapor to Ice –
On windows in the winter.
ADDING ENERGY
• Phase changes that require the addition of
energy are called endothermic changes.
(endo = inside, therm = heat)
• Which phase changes are endothermic?
• Melting (solid  liquid)
• Vaporization (liquid  gas)
• Sublimation (solid  gas)
REMOVING ENERGY
• Phase changes that require the removal of
energy are called exothermic changes.
(exo = outside, therm = heat)
• Which phase changes are exothermic?
• Freezing (liquid  solid)
• Condensation (gas  liquid)
• Deposition (reverse sublimation) (gas  solid)
Heat and Particle Theory
- Heat of fusion – The amount of energy
required to turn a sample of solid matter into
a liquid (ex. Ice to water)
- Heat of Vaporization – The amount of
energy required to turn a sample of liquid
matter into a gas
Temperature and Theory of Kinetic
Energy
- Kinetic Energy – Energy produced by the
constant motion and collision of particles of
matter
- - Temperature – The measure of the amount
of kinetic energy in matter
How are Kinetic Energy and Temperature
related?
DENSITY OF SOLIDS, LIQUIDS & GASES
• Does water as a liquid, water a solid, or water as a
gas have the highest density? Explain.
DENSITY
• Density can be described as the “crowdedness” of
the particles that make up matter.
• When you describe something as being “heavy” or
“light” you are referring to that something’s density.
• Each substance has its own, unique density.
• The closer the particles are together in a substance,
the higher its density is.