Increasing temperature increases the amount of kinetic energy the particles have. As a solid is warmed, its particles vibrate more vigorously about their fixed positions until they are able to break loose at the melting point (the temperature at which the solid and liquid both exist together). As we continue to heat the liquid, particles gain more kinetic energy until they have enough energy to break free from the forces of attraction holding them together at the boiling point. As we heat a gas, its particles continue to gain kinetic energy and speed, moving randomly. A gas usually has over 1000 times the volume of the solid or liquid. In the liquid, particles have a range (distribution) of kinetic energies. Occasionally a particle has enough energy to break free from the forces of attraction holding the particles in place. This is evaporation, and can happen at temperatures below the boiling point.
