the particulate nature of matter

The kinetic theory -

1. When a solid is heated, the particles vibrate about a fixed point. This causes particles to move further apart and so the solid expands.
2. When particles gain sufficient energy to overcome the forces of attraction holding then together, they can move out of their fixed positions. They can slip and slide past each other in a continuous random motion. When this happens the solid melts.
3. The particles in a liquid are still close to each other. They have enough kinetic energy to move around each other closely, but not enough to overcome the forces holding then together.
4. More heat energy is supplied and they move faster till they overcome the forces holding them together. The particles escape from the liquid surface and move in continuous rapid random motion. The liquid boils.
5. In the vapour, the particles move in rapid random motion. The movement is random due to the collision of vapour particles with air particles.
6. An increase in temperature will cause the particles to move faster and increase in pressure will cause gas particles to move closer together.

.When something gains heat, (melting and boiling) it's endothermic.

When something…