The phases of matter can change when different physical conditions exist. Temperature is one physical condition that can cause the state of matter to change. When the temperature increases, the phase of matter generally moves to a higher energy state. This means that the molecules are more active. A solid changes to a liquid then a liquid changes to a gas. As the temperature decreases, the molecules tend to move less.

Think of an ice cube, a solid. As the temperature increases, the ice cube will melt into water, a liquid. As the temperature of the water increases, the water will vaporize into a gas. As the gas cools, it will then condense into a drop of water.

Look at the chart below:

Change in Phase	Term	Example
Liquid to Gas	Vaporization	Water to water vapor
Gas to Liquid	Condensation	Water vapor to water
Solid to Liquid	Melting	Ice to water
Liquid to Solid	Freezing	Water to ice
Solid to Gas	Sublimation	Ice to water vapor
Gas to Solid	Deposition	Water vapor to ice