Why is the first ionisation energy of aluminium lower than that of magnesium?
Correct answer A. The electron removed from Al is in a 3p orbital, which is higher in energy and partly shielded by 3s electrons
Explanation
In Al the electron lost is the single 3p electron, which is higher in energy than the 3s electrons and is partly shielded by them. It is therefore easier to remove than a 3s electron from Mg.
Answer checked How we write and check questions
Discussion