Particle model of matter

• SOLID

  • particles are close together
  • particles arranged in a regular pattern
  • particles vibrate but do not move from place to place

  
• LIQUID

  • Particles close together
  • Particles not arranged in regular pattern
  • particles can move around each other

  
• GAS

  • Particles are very far apart
  • Particles not arranged in any pattern
  • Particles are moving very rapidly

  
• Density of a material tells us the mass for a given volume

  
  

  brick has a high density as it has lots of mass packed in its volume

  polystyrene has a low density as it has less mass packed in its volume
• density = mass / volume

  density in kg/m^3

  mass in kg

  volume in m^3
• SOLIDS have a high density as particles are packed together tightly and lots of mass in their volume
• LIQUIDS have a high density as particles are close together and have lots of mass in their volume.
• GASES have a low density as particles are very far apart so only have a small mass in their volume
• POLYSTYRENE is a solid but has a low density as it has lots of air spaces and a small mass for its volume
• Particles in solids, liquids and gases have kinetic energy and potential energy (intermolecular forces and chemical bonds).
• Internal energy is the energy stored in a system by the particles.

  Internal energy is the total kinetic energy and potential energy of all the particles that make up a system.
• when we heat a solid liquid gas we increase the internal energy.
• CHANGES OF STATE:

  When changes of state take place mass is always conserved.

  Physical changes not chemical changes.

  
• evaporation is when a liquid turns into gas but only on the surface of the liquid.
• specific heat capactiy:

  specific heat capacity of a substance is the amount of energy required to raise the temperature of 1kg of the substance by 1°C.
• specific heat capactiy:

  ΔE = m x c x Δθ

  change in thermal energy, ∆E, in joules, J

  mass, m, in kilograms, kg

  specific heat capacity, c, in joules per kilogram per degree Celsius, J/kg °C

  temperature change, ∆θ, in degrees Celsius, °C

  
  

  subtract degree Celsius to get temp change
• HEATING GRAPH:

  Temperature of the solid rises as we increase the energy of particles

  As it goes horizontal the solid turns into a liquid (melting)

  Energy being put is weakening the forces of attraction between the particles allowing it to be a liquid.

  Increasing the internal energy store not temperature.

  temperature rises again as we increased the energy of the particles

  
• COOLING GRAPH:

  as we heat or cool a substance we increase/decrease the temp aswell as the energy of the particles

  when the substance is freezing for example the temperature stops increasing as the energy we put in is weakening the forces of attraction between the particles.

  
• Specific latent heat of a substance is the amount of energy required to change the state of one kilogram of the substance with no change of temperature.
• Specific later heat of fusion: the energy required to change 1kg of a substance from a solid to a liquid with no change in temperature.

  Specific latent heat of vaporisation: the energy required to change 1kg of a substance from a liquid to a vapour with no change in temperature.
• latent heat equation

  energy f or a change o f state = mass × specific latent heat

  E = m x L

  energy, E, in joules, J

  mass, m, in kilograms, kg

  specific latent heat, L, in joules per kilogram, J/kg
• gas pressure is due to the particles colliding with the walls of the container that the gas is held in.
• we can increase the pressure of gas by increasing the number of collisions per second of the energy of each collision.
• low pressure - at low temperatures, particles how lower kinetic energy. There are fewer collisions per second. These are lower energy collisions.

  high pressure - At high temperatures, particles have higher kinetic energy. There are more collisions per second. These are higher energy collisions.