Question

explain why cation is smaller and anions are larger in radii than their parent atom

Answer 1

The outermost shell is completely removed by the loss of electron from an atom in the formation of cation and the value of effective nuclear charge increases on remaining electrons. So, the size of cation is always smaller than the neutral atom

Answer 2

Cations have smaller ionic radii than their parent atom because they contain less number of electrons. So, their nuclear charge remains the same. The lesser number of electrons present are pulled tightly by the nuclear force. So the cation 's atomic size is smaller than the parent atom.
This case is opposite to that of anion.


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