question_answer

There is a small increase in atomic radius is moving from P to As in group 15 elements as compared to large increase in atomic radius in moving from N to P in the same group. Explain.

Answer:

                The atomic radii of the three elements are: N(70 pm); P(110 pm) and As(121 pm). In moving from N to P, there is effective shielding by intervening s and p-electrons while it is comparatively poor by intervening -electrons which are involved in moving from P to As. As a result, the increase in atomic radius is less in this case.