Solids, liquids and gases

The three states of matter are solid, liquid and gas. The particle model represents particles by small, solid spheres. It describes the arrangement, movement and energy of particles in a substance. The model can be used to explain the physical properties of solids, liquids and gases.

Particle arrangement and movement

Table showing diagrams of solid, liquid and gas, their particle arrangements, movement and closeness.

The particles in the diagrams could be atoms, molecules or ions depending on the type of substance, eg ionic compounds, small molecules, giant molecules, and metals.

Explaining properties

A single particle does not have the properties of the material it is part of. The properties of a substance are the properties of a huge number of particles together.

Solids:

  • have a fixed shape and cannot flow, because their particles cannot move from place to place
  • cannot be compressed (squashed), because their particles are close together and have no space to move into

Liquids:

  • flow and take the shape of their container, because their particles can move around each other
  • cannot be compressed, because their particles are close together and have no space to move into

Gases:

  • flow and completely fill their container, because their particles can move quickly in all directions
  • can be compressed, because their particles are far apart and have space to move into