Molecular Motion
Atoms and molecules are always in motion.
• This includes changing locations as well as
vibration.
Atoms moving around
Atoms vibrating
0º C: atoms are
moving slowly
100º C: atoms are
faster
We measure this motion as heat.
• The faster the atoms/molecules, the
higher the temperature
“Absolute zero” is the temperature at which all
motion stops.
• It is a theoretical temperature. It cannot
actually be reached.
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Phases of Matter
Solid
• Stable shape
• Stable volume
Liquid
• No stable shape
• Stable volume
Gas
• No stable shape
• No stable volume
• Atoms/molecules are close together
• Atoms/molecules do not move
relative to each other
• Strong attraction between
atoms/molecules
• Atoms/molecules are further apart
• Atoms/molecules do move relative
to each other
• Weak attraction between
atoms/molecules
• Atoms/molecules are very far apart
• Atoms/molecules do move relative
to each other
• No attraction between
atoms/molecules
• High density
• Low energy
• Low speed
• Medium density
• Medium energy
• Medium speed
• Low density
• High energy
• High speed
Atoms/molecules
in solids line up in
rigid structures.
Atoms/molecules
in liquids are free
to move past each
other.
Atoms/molecules
in gases are far
apart and moving
independent of
each other.
Phases of Matter Diagram
Gas
Boiling
Sublimation*
Condensation
Liquid
Melting
Freezing
Solid
*Students are not responsible for knowing these
Deposition*