Arrangement, movement and energy

When a solid is heated the particles gain kinetic energy and start to vibrate faster about their fixed position. When the temperature is high enough, the vibration of particles becomes sufficient to overcome the forces of attraction between them. The particles begin to break away from their regular pattern. They can now slide past each other. The solid becomes a liquid.

When a liquid is cooled, the particles lose their kinetic energy. When the temperature is low enough, the particles no longer have the energy to slide over each other. The forces of attraction can hold the particles together in a regular pattern. The substance becomes solid.

When a liquid is heated, the particles gain kinetic energy and mover further apart. Eventually, the attractive forces in the liquid are broken. Bubbles of gaseous particles escape from the liquid. The substance becomes gas.

When a gas is cooled, the particles lose kinetic energy and the attractive forces become great enough to keep the particles closer together as a liquid.

The solid particles gain kinetic energy and vibrate faster. Eventually, the forces of attraction between the particles are completely broken and they escape from the solid as a gas.