Lanthanide contraction is due to increase in

Options

(a) shielding by 4f electrons
(b) atomic number
(c) effective nuclear charge
(d) size of 4f orbital

Correct Answer:

effective nuclear charge

Explanation:

As we move through the lanthanide series. 4f electrons are progressively filled. The mutual shielding effect of electrons is very little, being even smaller than that of d electrons.The nuclear charge however increases by one at each step increasing the inward pull experienced by the 4f electrons and hence the reduction in the size of the 4f(n) shell. Sum of the successive reductions gives the total lanthanide contraction.