Facts About Solids



  • Most substances can exist in three states — solid, liquid or gas. These are the states of matter.
  • Substances change from one state to another at particular temperatures and pressures.
  • As temperature rises, solids melt to become liquids. As it rises further, liquids evaporate to become gases.
  • The temperature at which a solid melts is its melting point.
  • The maximum temperature a liquid can reach before turning to gas is called its boiling point.
  • Every solid has strength and a definite shape as its molecules are firmly bonded in a rigid structure.
  • A liquid has a fixed volume and flows to take up the shape of any solid container into which it is poured.
  • A liquid flows because although bonds hold molecules together, they are loose enough to move over each other, rather like dry sand.
  • A gas such as air does not have any shape, strength or fixed volume. This is because its molecules are moving too quickly for any bonds to hold them together.
  • When a gas cools, its molecules slow down until bonds form between them to create drops of liquid. This process is called condensation.