Question

What happens to the atomic size of the lanthanides with increase in atomic number?

(a) The radius remains unchanged

(b) The radius decreases

(c) The radius increases

(d) The radius first increases and then decreases

The question was asked during a job interview.

This is a very interesting question from D and F-Block Elements in division D and F-Block Elements of Chemistry – Class 12

Answer 1

Right option is (b) The radius decreases

To explain: The gradual decrease in the atomic and ionic radii of the lanthanides with an increase in atomic number is called lanthanide contraction. It occurs due to the poor shielding effect of the 4f electrons.