Question

A sharp change in the atomic radius is observed from lithium to potassium but a gradual change in the atomic radius is observed from potassium to caesium. Explain.

• A. 0

Answer 1

The correct option is A 0
A sharp increase in the atomic radius is observed from lithium to potassium due to increase in the number of shells. But a gradual change is observed from potassium to caesium due to filling up of d electrons, in the penultimate shell which increases the effective nuclear charge. Hence increase in size is gradual, not sharp.