Question

Select from each group the species which has the smallest radius starting appriate reason.
(a) `O, O^(-), O^(2-)` (b) `P^(3+), P^(4+), P^(5+)`

Answer 1

(a) `O` is having smallest radius. Anion is larger than its parent atom. Also the anion of the same atom with higher negatie charge is bigger in size as compared to anion with smaller negative charge as proton to electron ratio decreases thus attraction between valence shell electrons and nucleus decreases. Hence electron cloud expands.
(b) The ionic radius decreases as more electrons are ionized off heat is as the valency increases. So the correct order is `P^(5+) lt P^(4+) lt P^(3+)`.