| Term | Definition |
|---|---|
| Altitude | vertical distance, or elevation, above sea level. |
| Boil | change from a liquid to a gas. |
| Boiling point | the temperature at which boiling occurs. |
| Freeze | change from a liquid to a solid |
| Freezing point | the temperature at which freezing occurs. |
| Gas | a phase in which matter has no definite shape or volume. |
| Gas properties | will expand to fill any container; can be compressed; molecules relatively far apart and move freely. |
| Water vapor | water in the gas phase |
| Liquid | a phase in which matter has definite volume but no definite shape. |
| Liquid properties | will take the shape of a container but cannot expand or be compressed; molecules in a liquid move randomly but stay close to one another. |
| Melt | change from a solid to a liquid. |
| Melting point | the temperature at which melting occurs. |
| Phase | a state of matter with certain physical properties |
| Solid | a phase in which matter has a definite shape and a definite volume. |
| Solid properties | will retain the same shape and volume in any container; atoms are held in a rigid structure and cannot move freely |
| Ice | water in the solid phase |
| Thermal energy | Energy in the form of heat |
| Vaporization | rapid change from liquid to gas |
| Condensation | change from gas to liquid |
| Sublimation | change from solid to gas |
| Evaporation | slow change from liquid to gas |
| Deposition | change from gas to solid |
