a. Write equations that describe:

i. The 1st ionisation energy of calcium
ii. The 3rd ionisation energy of potassium
iii. The 2nd ionisation energy of lithium
iv. The 5th ionisation energy of sulfur.

b. The 2nd ionisation energy of nitrogen is 2860 kJ mol^–1. The 3rd ionisation energy of nitrogen is 4590 kJ mol^–1. Explain why the 3rd ionisation energy is higher.