Ionisation energy down groups

Question 1

The ionisation energy down a group decreases due to the following factors:

Answer 1

The number of protons in the atom is increased, so the nuclear charge increases

But, the atomic radius of the atoms increases as you are adding more shells of electrons, making the atoms bigger
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The shielding by inner shell electrons increases as there are more shells of electrons

Question 2

Why does the the atomic radius of the atoms increases as you are adding more shells of electrons, making the atoms bigger counteract

The number of protons in the atom is increased, so the nuclear charge increases

Answer 2

So, the distance between the nucleus and outer electron increases as you descend the group

Question 3

How does The shielding by inner shell electrons increases as there are more shells of electrons mean ionisation energy decreases

Answer 3

These factors outweigh the increased nuclear charge, meaning it becomes easier to remove the outer electron as you descend a group