Chapter 16 Lesson 1
Kinetic Theory
States of Matter
– Kinetic Molecular Theory
– Four States of Matter
– Thermal Expansion
Kinetic Molecular Theory

KMT
– Tiny, constantly moving particles make up
all matter.
– The kinetic energy (motion) of these
particles increases as temperature
increases.
– These particles are colliding with each
other and the walls of their container.
Four States of Matter

Solids
– low KE - particles vibrate but
can’t move around
– atoms held tightly into place
– definite shape & volume
Four States of Matter

Liquids
– higher KE - particles can move
around but are still close
together
– indefinite shape
– definite volume
Four States of Matter

Gases
– high KE - particles can separate
and move throughout container
– indefinite shape & volume
– move more quickly than particles
that make up solids
Four States of Matter

Plasma
– very high KE - particles collide with
enough energy to break into charged
particles (+/-)
– gas-like, indefinite
shape & volume
– stars, fluorescent
light bulbs, TV tubes
Phase Changes

Heat of fusion-melting
– solid to liquid.
– energy required to change a substance
from the solid phase to the liquid phase at
its melting point is known as the
– some attractive forces are broken

Freezing
– liquid to solid
melting point = freezing point
Phase Changes

Heat of vaporization
– energy required for the
liquid at its boiling point
to become a gas.
– all attractive forces are
broken
– EX: steam burns,
sweating, and… the
drinking bird
Heating Curves

Evaporation
– liquid to gas below the boiling point

Condensation
– gas to liquid
Heating Curves
Gas - KE 
Boiling - PE 
Liquid - KE 
Melting - PE 
Solid - KE 
Phase Changes

Sublimation
– solid to gas
– EX: dry ice,
freeze drying,
iodine
Phase Changes
Thermal Expansion

Most matter expands when
heated & contracts when
cooled.

 Temp causes  KE.
Particles collide with more
force & spread out.

EX: thermostats (bimetallic
strip)
Heating Curves

Kinetic Energy
– motion of particles
– related to temperature

Potential Energy
– space between particles
– related to phase changes
Solid or a Liquid?
Amorphous solids and liquid crystals
– two classes of materials don’t react as
expected when changing states.
– solids soften and gradually turn into a
liquid over a temperature range
– lack the highly ordered structure found in
crystals
– are typically long, chainlike structures that
can get jumbled and twisted
The Strange Behavior of
Water
Water molecules
– unusual in that they have highly positive
and highly negative areas
– charged regions affect its behavior
– as the temp drops the particles move
closer together
The Strange Behavior of
Water
Freezing water molecules
– unlike charges are attracted to each other
and line up so that only positive and
negative zones are near each other.
– water molecules orient themselves
according to charge, empty spaces occur in
the structure.
– these empty spaces are larger in ice than
in liquid water, so water expands when
going from a liquid to a solid state.
Liquid Crystals
LCD
– flow during the melting phase similar to a
liquid, but they do not lose their ordered
arrangement completely.
– placed in classes depending upon the type
of order they maintain when they liquefy
– are highly responsive to temperature
changes and electric fields.
– ex: televisions, watches, clocks, and
calculators