Gases, liquids and solids

1. Gases

• Gases are often invisible.
• Gases do not keep their shape or always take up the same amount of space. They spread out and change their shape and volume to fill up whatever container they are in.
• Gases can be squashed.
• Heating a liquid can turn it into a gas.
• Cooling a gas can turn it into a liquid.
  
  Examples of gases