Energy
What is energy?
Energy is the ability to do work!
Phase Changes and Energy
The 3 Phases of Matter
What does state of matter have to do with energy?
Each state (or phase) of matter has a different amount of
energy depending on how fast its molecules move and
how spread out they are.
The state that matter is in depends on
its thermal energy or heat
Water exists in all
3 states but its
molecules will have
different amounts
of energy
Energy and Phase Changes
In order to change state
or phase, matter must
either gain or lose
energy. This will change
how the molecules are
arranged.
Molecules in each state of matter
have different amounts of
movement, spacing and energy.
Melting
What happens to a
substance as it melts?
The molecules gain
enough energy that
they vibrate too much
to stay in an organized
pattern.
The change from a solid to a liquid is
called melting. Most substances melt
at a specific temperature.
Freezing
When the substance hits
its freezing temperature,
its particles slow down,
come together, and form
regular patterns.
Overall, they lose energy.
If water cools down to O°C,
it will freeze.
Condensation
Do you think the
water is gaining
or losing energy?
Condensation
If a gas loses enough energy,
it can turn back into a liquid.
As the gas cools, the molecules
slow down and get closer
together.
This can happen when the gas
bumps into something cool like
a soda can or a mirror.
Sublimation
Do you think the
water is gaining
or losing energy?
Sublimation
Sometimes the
molecules of a
solid gain enough
energy to turn
right into a gas,
skipping the
liquid phase.
Deposition
Do you think the
water is gaining
or losing energy?.
Deposition
If a gas loses a
lot of heat very
rapidly, it will
turn directly into
a solid. This is
called deposition.
When water changes phases
Boiling
Melting
Temperature doesn’t change
during a phase change!
So, let’s sum it all up…
Moving towards a gas always involves an INCREASE in energy
Moving towards a solid always involves an DECREASE in energy