Change of state
The transformation of one state of matter to another, for example, solid to liquid, liquid to solid, liquid to gas.
Melting point (mp)
The temperature at which a solid becomes a liquid (melts). It is the same temperature as the freezing point.
Melting
The change of state from a solid to a liquid.
Freezing
A change from liquid to solid.
Freezing point (fp)
The temperature at which a liquid changes to a solid (freezes) and a solid changes to a liquid (melts).
Heat of fusion
The energy required to melt exactly 1 g of a substance at its melting point.
Evaporation
The formation of a gas (vapor) by the escape of high-energy molecules from the surface of a liquid.
Boiling point (bp)
The temperature at which a liquid changes to gas (boils) and gas changes to liquid (condenses)
Boiling
The formation of bubbles of gas throughout a liquid.
Condensation
The change of state from a gas to a liquid.
Heat of vaporization
The energy required to vaporize 1 g of a substance at its boiling point.
Heating curve
A diagram that illustrates the temperature changes and changes of state of a substance as it is heated.
Cooling curve
A diagram that illustrates temperature changes and changes of state for a substance as heat is removed.
Sublimation
The change of state in which a solid is transformed directly to a gas without forming a liquid first.
Deposition
The change of a gas directly to a solid; the reverse of sublimation