Question

Why is the ionisation energy of gallium more than aluminium?

Answer 1

This is because of ineffective shielding because of the persence of 'd' orbitals

Answer 2

Answer:

This is because in ga 10 electrons are filled in d orbital whereas in al there is no electron in d orbital. Now as we know d orbital has poor shielding effect. Hence effective nuclear charge of ga increases resulting in decrease of its size. Therefore size of ga is smaller than al and smaller the size greater is the ionisation enthalpy. So first ionisation enthalpy of al is less than ga.

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