Atomic structure: describe question

The first ionisation energies of sodium (Na) and magnesium (Mg) are 496 kJ mol⁻¹ and 738 kJ mol⁻¹ respectively. The second ionisation energy of sodium is 4563 kJ mol⁻¹ and that of magnesium is 1451 kJ mol⁻¹.

Construct equations for the first and second ionisation energies of each element. Describe and explain the differences in the first ionisation energies of sodium and magnesium, and explain why the second ionisation energy of sodium shows a much larger increase relative to its first than does magnesium.