* Liquids turn into gas when the particles get *warmer*. As the particles gain energy (heat), they move faster and overcome the forces holding them together in the liquid state. This causes them to escape into the gaseous state.

* Liquids turn into solids when the particles get *colder*. As the particles lose energy (heat), they move slower and the forces holding them together become stronger. This causes them to become more tightly packed, transitioning to a solid state.

Think about water:

* Ice (solid) forms when water gets cold enough.

* Liquid water exists at temperatures between freezing and boiling.

* Steam (gas) forms when water gets hot enough.