1.1. Higher Tier Only

Explain why the masses and charges of subatomic particles are described as ‘relative atomic masses’ and ‘relative atomic charges’.

1.2. Compare the relative sizes of the following things: atom, nucleus and electrons. 

1.3. The diagram shows the chemical symbol of magnesium and lithium.

${Mg}_{12}^{24}$                             ${Li}_{3}^{7}$

Explain the difference in nucleon number of an atom of magnesium and the nucleon number of an atom of lithium. 

1.4. Higher Tier Only

Explain why percentage abundance of isotopes is taken into consideration when calculating the relative atomic mass.