- from Matter
Water freezes. Ice melts. Steam condenses. These are ways that water—and all matter—can change. Scientists refer to these changes as changes in state, and they’re all about energy, specifically heat energy.
Matter can change from one state to another and back, over and over again. The molecules that make up the matter do not change. A molecule of water is still H20 whether it has the energy of vapor (a gas), water (a liquid), or ice (a solid).