particle model of matter

• states of matter:

  physical change, recovers its original properties if change is reversed

  mass is the same

  
• solids:

  • arrangement - regular arranged, tightly packed
  • motion - vibrate in fixed positions
• liquids:

  • arrangement - close together but not in fixed positions
  • motion - move around each other
• gas:

  • arrangement - far apart
  • motion - quickly and randomly
• physical changes:

  • melting - solid to liquid
  • evaporating - liquid to gas
  • boiling - liquid changes to gas at boiling point
  • condensing - gas to liquid
  • freezing - liquid to solid
  • sublimation - solid to gas

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  • melting point - the temperature at which a substance changes from solid to liquid
  • boiling point - the temperature at which a substance changes from a liquid to a gas
• internal energy:

  • energy is stored inside a system by the particles that make up a system
  • particles - atoms and molecules
  • total kinetic and potential energy in a system
  • kinetic - movement
  • potential - how close the particles are to one another
  • heating up a system increases the particles that make up that system's energy which causes it to increase in temperature or change state
• specific latent heat:

  • energy required to change the state of 1kg of a substance without a change in temperature
  • when a change of state occurs, the energy supplied changes the internal energy but not the temperature
  • the energy needed for a substance to change state is called latent heat
  • specific latent heat of fusion - change state from solid to liquid
  • specific latent heat of vaporisation - change state from liquid to gas
• heating and cooling graphs:

  *vaporisation -> evaporation

  
• particle motion in gases:

  • the molecules of the gas collide with the walls of the container exerting an outside force at a right angle to the walls of the container
  • increasing the temperature of the gas at constant volume increases the pressure
  • more energy supplied to the kinetic energy of the molecules so they move more and collide with the walls of the container more often increasing the force on the walls of the container and increases the pressure
  • increasing the volume of the gas at constant temperature decreases the pressure
• increasing pressure:

  • compressing a gas leads to an increase in temperature e.g. a bicycle pump
  • work is the transfer of energy by a force
  • doing work on a gas increases the internal energy of a gas and could cause an increase in temperature of the gas