States of matter

• States of matter

  Solid, liquid, gas
• Particle Theory Model


  • All matter is made up of tiny particles
  • Describes the movement of particles
  • Describes the average distance between particles
• Solid

  • Particles are in a regular arrangement and vibrate on the spot
  • Particles are close together with no space to move
  • Fixed shape, cannot flow
  • High density
  • Particles have little energy but vibrate constantly
• Liquid

  • Particles are in a random arrangement and can move around each other
  • Particles are close together
  • Can flow and take the shape of their container
  • Quite dense
  • Particles have more energy than in solids
• Gas

  • Particles are in a random arrangement and move quickly in all directions
  • Particles are far apart
  • Gases flow and completely fill their container
  • Very low density
  • Particles have lots of energy and move around at high speed
• Changes of state

  1. Melting

  2. Evaporation

  3. Condensation

  4. Freezing
• Melting


  Solid particles gain more energy, vibrate more, attractions are no longer strong enough to hold them in position, solid becomes a liquid
• Freezing/Solidifying


  Liquid particles lose energy, vibrate less, forces of attraction are enough to stop them moving, a solid has now formed
• Boiling


  Liquid is heated so strongly that particles move fast enough/have enough energy to break all forces of attraction, bubbles of gaseous particles rise to the surface forming a gas
• Evaporation


  Not all particles in a liquid contain the same amount of energy - some have more, this is why evaporation of a liquid can take place below its boiling point
• Condensing


  When a gas is cooled, the particles lose energy, this loss in energy causes the particles to move more slowly as they move closer together, attractions hold the particles together as a liquid
• Sublimation

  Under some conditions, some solids turn straight into a gas, the opposite of deposition
• The melting point is the same as the freezing point, the boiling point is the same as the condensation point
• Gases will liquefy if pressure is increased enough because the particles are moved closer together
• A change in state is the change of a substance from one physical form (solid, liquid, gas) to another, this occurs due to gaining or releasing energy
• A change in state is a physical change, not a chemical change
• As a gas is cooled down to below its freezing point


  Particles lose energy and therefore move slower, the particles move in closer together and form bonds between them, changing their state from a liquid to a solid
• Substances have different melting points


  Different particles have different types of bonds between them, some require more energy to break and will have higher melting points, others will have weaker bonds and not require as much energy, lower melting point
• The particle model has limitations because different substances are made up of different particles (e.g. atoms, ions or molecules) that can vary in size and the interactions between them can distort their shape, and atoms are mostly empty space so real particles are not solid at all
• Water has a higher melting and boiling point than methane because water has stronger bonds between its particles
• Solids, liquids and gases all have in common that they are made up of tiny particles
• Solids have the strongest attractions between their particles
• Solids cannot be compressed because the particles are close together with no space to move into
• A solid becomes a liquid when the particles gain enough energy to break the attractions holding them in fixed positions
• Exceptions to changes of state include sublimation, where some solids turn straight into a gas
• Heating and cooling curves can be used to monitor changes of state over time