Question #de1b8
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When steam condenses to form liquid water it releases a lot of heat. Principally, the bonds between molecules are chemical. The formation of these bonds corresponds to the change in phase. Molecules that were free to wander are now joined with electromagnetic bonds and behave like a fluid. Molecules once in free motion with a lot of kinetic energy are now joined together and unable to move quite so far without transferring momentum to molecules near them.
Definitions of Energy vary a little by state standards. And scientists aren't always very good about using terms consistently. Chemists, for example, like to speak of entropy instead. If you are in a state which uses the SCREAM acronym, you may have the choices: Sound, Chemical, Radiant, Electrical, Atomic, and Mechanical. You could make a case for many of these so-called forms of energy playing a role in phase-change dynamics.
Depending on the context of the question and how deep you want to get into the theory, one could talk about kinetic energy, chemical energy, heat energy, electric or magnetic bond energy. Heat is really a consequence of the motion of many many molecules considered as a statistical whole. Individually, the molecules simply follow Newton's Laws and react to the net force acting on their mass at any time.
