1. Evaporation may occur when water is left in an open container. The liquid water turns to a vapor and the volume of liquid may decrease over a period of time. This occurs because the molecules at the surface of the water escape into the atmosphere, a liquid to gas state.
2. When water is heated, it causes the water molecules to vibrate and move apart. It boils and when it reaches it's boiling point, the energy from the heat converts the water into gas vapor. When water is cooled, at a temperature of 4 C it's molecules will contrast , when it reaches the freezing point, it expands by 9%.
3. When solid ice gain heat, it changes state from from solid ice to liquid water in a process called melting. Ice cubes in a cold drink, for example gradually melt. When water absorbs enough heat, it becomes a gas (water vapor). This process is called evaporation.
