Density of materials

The density of a material is defined by the equation:

\(\text{density} = \dfrac{\text{mass}}{\text{volume}}\)

\(\rho = \dfrac{m}{V}\)

density, ρ, in kilograms per metre cubed, kg/m³
mass, m, in kilograms, kg
volume, V, in metres cubed, m³

The particle model can be used to explain
- the different states of matter
- differences in density.

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Students should be able to recognise/draw simple diagrams to model the difference between solids, liquids and gases.

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Students should be able to explain the differences in density between the different states of matter in terms of the arrangement of atoms or molecules.

Changes of state

Students should be able to describe how, when substances change state (melt, freeze, boil, evaporate, condense or sublimate), mass is conserved.

Changes of state are physical changes which differ from chemical changes because the material recovers its original properties if the change is reversed.