Solids, liquids and gases. In a solid like this brick, the particles are regularly arranged touching their neighbours and move only by vibrating. This explains why solids have a fixed shape.

The density of solid iron = 7.8 g/cm 3 The density of liquid iron = 6.9 g/cm 3 A substance evaporates when it changes from the liquid state to the gas state. Its particles move freely and are very ...