Gases

Air, helium and chlorine are gases at room temperature. Water vapour is water as a gas. The particles in a gas are:

  • far apart
  • arranged in a random way
Gas particles are far apart in a random pattern, and can move freely and quickly.Particles in a gas

The particles in a gas can:

  • move quickly in all directions

The attractive forces between the particles in a gas are very weak, so the particles are free to move in any direction.

The table shows some of the properties of gases and why they are like this:

PropertyReason
They flow and completely fill their containerThe particles can move quickly in all directions
They can be compressed (squashed)The particles are far apart and have space to move into