Liquid to Solid (Freezing):

* What happens: When liquid water is cooled below its freezing point (0 degrees Celsius or 32 degrees Fahrenheit), the water molecules slow down. This causes the molecules to arrange themselves into a regular, crystalline structure.

* Why it happens: The slower movement of the molecules allows them to form strong, rigid bonds, creating the solid form of water, which is ice.

Liquid to Gas (Boiling or Evaporation):

* What happens: When liquid water is heated, the water molecules gain energy and start moving faster. Eventually, some molecules gain enough energy to break free from the liquid surface and escape into the air as water vapor (gas).

* Boiling: This happens at a specific temperature (100 degrees Celsius or 212 degrees Fahrenheit) called the boiling point. At this temperature, the vapor pressure of the liquid equals the pressure surrounding the liquid.

* Evaporation: This can happen at temperatures below the boiling point, as some water molecules always have enough energy to escape the liquid surface.

Key takeaway: The changes between liquid, solid, and gas states of water are all about the movement of water molecules and the bonds they form.