States of Matter
Kinetic Molecular Theory
 Explanation for atoms/molecules’ behavior within a
state of matter.
 Views atoms/molecules within matter in constant
motion.
 Explains properties associated with solids, liquids, and
gases
3 Phases of Matter
 Solid
 Liquid
 Gas
How do particles move in a solid?
Solids
 Have a definite shape/structure, high density (most), cannot be
compressed
 Very little particle movement—fixed position
 “vibrate” in a fixed position
 Intermolecular forces strongest in this state of matter
 Crystals– particle arrangement in a repeating, geometric pattern
 Amorphous solid– soild with random arrangement of particles
How do particles move in a liquid?
Liquids
 Limited structure to particles, definite volume
 Diffusion is possible (liquids can mix together), more
compressible than solids
 Movement is less restricted, particles can move around and
collide with each other
 Less intermolecular force attraction among these particles
 Conform to a container’s shape, exhibits “flow”—fluid
 Exhibit surface tension (force allowing the liquid to adhere
to a surface)
Gases
 No structure—no definite volume or shape
 Movement is not restricted
 Fluid—gas particles can “flow” among each other
 Particles are always in motion
 Expansion occurs but capable of being compressed
 Least dense state
 Diffusion is possible (gases can mix together)
Phase Changes
 Boiling/Evaporation—a liquid is changing to a gas
 Condensation—a gas is changing into a liquid
 Sublimation—a solid converts directly into a gas, skips
the liquid phase
 Melting and freezing ????
Phase Diagrams
 Graph plot of temperature vs. pressure
 Indicates what physical conditions MUST exist for each
phase of a substance
 Specific for each substance
Phase Diagram of Water
 Equilibrium– balanced state, 2 opposite changes are
happening at equal rates
 Critical Point– point on the diagram where substance cannot
be converted back into a liquid from a gaseous state
 Contains both critical temperature ( > than, cannot go back to
liquid) and critical pressure (lowest pressure for liquid state at
critical temperature)
 Triple Point– point on the diagram where a substance exists
in equilibrium between all three phases (solid, liquid, gas)
 Melting Point– a substance goes from a solid to a liquid at
this temperature
 Boiling Point– liquid vaporizes, the external atmosphere
pressure = vapor pressure of the liquid