States of Matter

• Materials come in three different forms - solid, liquid and gas. These are the Three States of Matter.
• Which state you get depends on how strong the forces of attraction are between the particles of the material.
• How strong the forces are depends on THREE THINGS:

  • the material
  • the temperature
  • the pressure
• Solids


  There are strong forces of attraction between particles, which hold them close together in fixed positions to form a very regular lattice arrangement.
• Solids


  The particles don't move from their positions, so all solids keep a definite shape and volume, and don't flow like liquids.
• Solids


  The particles vibrate about their positions - the hotter the solid becomes, the more they vibrate (causing solids to expand slightly when heated).
• Liquids


  There is a weak force of attraction between the particles. They're randomly arranged and free to move past each other, but they tend to stick closely together.
• Liquids


  Liquids have a definite volume but don't keep a definite shape, and will flow to fill the bottom of a container.
• Liquids


  The particles are constantly moving with random motion. The hotter the liquid gets, the faster they move. This causes liquids to expand slightly when heated.
• Gases


  The force of attraction between the particles is very weak - they're free to move and are far apart. The particles in gases travel in straight lines.
• Gases


  Gases don't keep a definite shape or volume and will always fill any container.
• Gases


  The particles move constantly with random motion. The hotter the gas gets, the faster they move. Gases either expand when heated, or their pressure increases.
• Physical changes don't change the particles - just their arrangement or their energy.
• State Change


  1. When a solid is heated, its particles gain more energy
• State Change


  2. This makes the particles vibrate more, which weakens the forces that hold the solid together. This makes the solid expand.
• State Change


  3. At a certain temperature, the particles have enough energy to break free from their positions. This is called melting and the solid turns into a liquid.
• State Change


  4. When a liquid is heated, again the particles get even more energy.
• State Change


  5. This energy makes the particles move faster, which weakens and breaks the bonds holding the liquid together.
• State Change


  6. At a certain temperature, the particles have enough energy to break their bonds. This is called evaporating and the liquid turns into a gas.