The Energy of Gases, Solids and Liquids
The three basic states of matter have different amounts of kinetic (movement) energy: in a solid, the particles vibrate about a fixed point. If you add heat energy to a solid, the particles will vibrate with larger and larger amplitudes ('wobbles') and eventually more and more of these particles will be able to break their solid bonds to form a liquid (melting).
Liquids have more kinetic energy than solids. If you add heat energy to a liquid, the particles will move faster around each other as their kinetic energy increases. Some of these particles will have enough kinetic energy to break their liquid bonds and escape as a gas (evaporation).
Even water in a puddle on a cool day has some particles with enough energy to break their liquid bonds and become a gas. There will be enough of these particles so that after several hours the puddle has evaporated into a gas.
GCSE Physics Keywords: Kinetic energy, Solid bonds, Liquid bonds, Vibrate, Heat energy, Breaking bonds, Melting, Evaporation.