Particles and states of matter · Year 8
All matter is made of tiny particles that are always moving. How closely they are packed and how freely they move explains the properties of solids, liquids and gases, why gases can be squashed, why smells spread, and what really happens when things melt or boil.
Key facts
- Solid: particles close together in a regular pattern, vibrating about fixed positions.
- Liquid: particles close together but randomly arranged, sliding past each other.
- Gas: particles far apart, moving quickly and randomly.
- Diffusion: particles spread from where there are many to where there are fewer; faster when hotter.
- Internal energy = total kinetic + potential energy of the particles.
- Heating raises the temperature (more kinetic energy) or changes the state (more potential energy).