Representation of the states of matter

Solids consist of molecules held in a fixed pattern. The molecules in a solid vibrate about their fixed positions, and the hotter it is, the faster they vibrate. Solids therefore have a fixed shape and expand slightly as they heat.

Solids melt into liquids when the molecules have enough heat energy that their movement and vibration is fast enough that they break away from the bonds that hold the molecules in a fixed pattern.

Molecules in a liquid have some attraction to themselves, but are not bonded into a fixed pattern so they move around amongst themselves and take up the shape of the bottom of the container they are in.

Liquid molecules evaporate into gas molecules when they have enough heat energy to break away from their attraction.

Gas molecules fly around and fill the container they are in. the hotter it is, the faster they travel.

If it gets colder, gas molecules travel more slowly until they condense to form a liquid.

If it gets even colder, liquid molecules form bonds to freeze and make a solid.