1. Phase Changes
A change from one state of matter (solid, liquid, gas) to another.
Physical change because appearance is changed, not chemical make-up; reversible.
Heat energy is either absorbed (molecules speed up) or released (molecules slow down)
Ex. Melting: Ice to water; heat absorbed

2. Types of Phase Changes

3. Melting Phase change from a solid to a liquid
Molecules speed up, move farther apart, and absorb heat energy

4. Freezing Phase Change from a liquid to a solid
Molecule slow down, move closer together and release heat energy.

5. Evaporation
Phase change from a liquid to a gas (occurs at the boiling point)
Molecules speed up, move farther apart, and absorb heat energy.

6. Condensation Phase change from a gas to a liquid.
Molecules slow down, move closer together and release heat energy.

7. Sublimation Phase change from a solid to a gas.
Molecules speed up, move farther apart, and absorb heat energy.

8. Deposition Phase change from a gas to a solid.
Molecules slow down, move closer together and release heat energy.
Vapor in air turns directly into frost on a windshield