Summary AQA GCSE Physics Combined Science - Particle Model of Matter Notes

PARTICLE MODEL OF MATTER

CHANGES IN STATE
 SOLID
o Vibrate in a fixed position
o Closely packed
o Strong forces of attraction
 LIQUID
o Can slide over each other due to weaker forces of attraction
o More kinetic energy than solids
o Close together
 GAS
o Low density
o Can be compressed
o Very weak forces
 Heating increases the energy the particles have and can produce a change of state
 Mass in conserved during a change of state




DENSITY
 Density is defined as the mass per unit of volume
 Density = mass/volume
 Solids and liquids have similar densities as the space between the particles does not change
significantly
 Gases have a far lower density
o The particles have lots of energy to move, so the volume increases greatly and
therefore the density decreases
 Less dense objects rise




TEMPERATURE CHANGES
 A change in state requires energy known as latent heat
 Melting: mLfus – latent heat of fusion
 Boiling: mLvap – latent heat of vaporisation




PRESSURE
 The temperature of a gas is related to the average kinetic energy of the molecules