The three states of matter

• Solids

  • Extremely hard to compress
  • Fixed shape, cannot flow
• Particles in solids

  Packed together in a regular pattern with almost no spaces between them
• Liquids

  • Extremely hard to compress
  • Take the shape of their container, can flow
• Particles in liquids

  Close together with not many spaces, can move
• Gases

  • Extremely easy to compress
  • Spread out and fill the space of their container
• Particles in gases

  Widely spaced, move quickly and randomly
• Melting

  1. Heating a solid to change it to a liquid

  2. Occurs at the melting point
• Particles in a liquid

  Have more kinetic energy than particles in a solid
• Stronger forces of attraction between particles

  Higher melting point
• Solids with different melting points

  • Wax candle (relatively low)
  • Sodium chloride (very high)
• Freezing

  1. Cooling a liquid to change it to a solid

  2. Occurs at the melting point
• Boiling

  1. Heating a liquid to change it to a gas

  2. Occurs at the boiling point
• Stronger forces of attraction between particles

  Higher boiling point
• Condensing


  1. Cooling a gas to change it to a liquid

  2. Occurs at the boiling point
• Limitations of simple particle model

  • Assumes particles are solid spheres (not true)
  • Assumes no forces between particles (not true)