Particle Model of Matter

• Why are gases less dense than solids?

  The particles are more spread out (same mass over a larger volume)
• Solids

  • Particles closely packed together
  • Particles cannot move, only vibrate about fixed positions
  • Have a definite shape
  • Have a definite volume
• Liquids

  • Closely packed particles
  • They are able to flow over one another
  • They have a fixed volume
  • They do not have a fixed shape because the particles are able to flow over each other and they take the shape of their container
• Gases

  • Particles are far apart
  • Particles move randomly
  • No definite shape
  • No definite volume
  • Highly compressible because there are large gaps between particles so it is easier to push them together
• Internal energy

  The total energy stored inside of a system by the particles that make up the system due to their motion and positions
• What happens during a state change?

  As a substance approaches its melting/boiling point the energy is no longer transferred to the kinetic energy store so the temperature remains constant. However the energy is now transferred to the potential energy store which is used to break/make the intermolecular forces of attraction.
• What is specific latent heat?

  The amount of energy needed to change the state of 1kg of a substance without changing the temperature
• What is the difference between latent heat of fusion and vaporisation?

  Fusion: Changing between solid to liquid

  Vaporisation: Changing between liquid to gas
• What is the equation for specific latent heat?

  E=mL
• What is the equation for specific heat capacity?

  $E=$$mc\Delta\theta$