Solid-When a solid is heated the particles gain energy and start to vibrate faster and faster. Initially the structure is gradually weakened which has the effect of expanding the solid. Further heating provides more energy until the particles start to break free of the structure. Although the particles are still loosely connected they are able to move around. At this point the solid is melting to form a liquid.
Liquid-As the liquid gets warmer more particles have sufficient energy to escape from the liquid. Eventually even particles in the middle of the liquid form bubbles of gas in the liquid. At this point the liquid is boiling and turning to gas. The particles in the gas are the same as they were in the liquid they just have more energy. At normal atmospheric pressure all materials have a specific temperature at which boiling occurs. This is called the "boiling point" or boiling temperature.
Description of Phase Change Term for Phase Change Heat Movement During Phase Change
Solid to liquid Melting Heat goes into the solid as it melts.
Liquid to solid Freezing Heat leaves the liquid as it freezes.
Liquid to gas Vaporization, which includes boiling and evaporation. Heat goes into the liquid as it vaporizes.
Gas to liquid Condensation Heat leaves the gas as it condenses.
Solid to gas Sublimation Heat goes into the solid as it sublimates.
