Particle Model of Matter

This unit covers density, the three states of matter, internal energy, specific heat capacity, specific latent heat, changes of state, and gas pressure.

Density calculations open the unit and include a required practical on measuring density, which is examined directly. The particle model explains everything that follows, so be able to describe the arrangement, motion and relative energy of particles in each state. Specific heat capacity and specific latent heat are frequently confused: heat capacity concerns temperature change, latent heat concerns change of state at constant temperature. Heating and cooling curves reward explaining why the temperature plateaus during a change of state. Students lose marks by describing a change of state as a chemical change, and by forgetting that mass is conserved when a substance melts or boils.