Question

Why anion is larger than its parent atoms??​

Answer 1

Answer :-

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The formation of anion takes place when an atom gains electrons.

Example:- Br + 2e- → Br(2-)

(2-) is it's valency.

Now, when it gains electrons, there's no change in the composition of it's nucleus (that is, the number of nucleons or better to say protons). So, the Nuclear charge remains the same due to which the nuclear pull on the valence shell will also remain the same. But the valence shell gains electrons and stabilizes itself due to which the nuclear force can no longer pull it with the same force. This results in the increase in atomic radii of the ion (more specifically, anion).

Therefore, Anion is larger in size than the parent atom.

The opposite happens in the case of cation.

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