GCSE Science | Particle Model

Physics changes and chemical changes

• physical changes
  • mass is conserved
  • the material regains its original properties if the change is reversed

Density

• density = mass/volume
  • mass - kg
  • volume - m³
  • density - kg/m³

Solids, liquids and gases

(arrangement and movement of particles)

• solids
  • particles are close together in neat rows and columns
  • particles vibrate a little
• gases
  • particles are spread out
  • particles move in random directions and hit the container
• liquids
  • particles are close together but not in a regular arrangement
  • particles move slowly within their given volume
• changes of state
  • s-l - melting
  • l-g - evaporation
  • g-l - condensing
  • l-s - freezing
  • s-g - sublimation

Energy changes

• when particles gain energy, this can lead to either:
  • increase in temperature
  • change in state
• internal energy - the kinetic and potential energy of particles

Specific heat capacity

• the amount of energy needed to increase the temperature of 1kg of a substance by 1^o C
• E = mc△T
• E: Energy (J)
• m: mass (kg)
• T: temperature (^o C)
• c: specific heat capacity (J/kg ^o C)

Specific latent heat

• the amount of energy needed to change the state of 1kg of a substance
• E = mL
• L: specific latent heat (J/kg)