Question

What is meant by Lanthanide contraction? Write the general electronic configuration of inner transition elements. 

Answer 1

Lanthanide contraction
It is the slow or gradual decrease in the sizes of atoms or tri positive ions of lanthanide as we move from left to right along the lanthanides.
General electronic configuration of inner transition elements is
[Xe]₅₄ 4f^1-14 5d^0-1 6s² – For lanthanides
[Rn]₈₆ 5f^1-14 6d^0-1 7s² – For actinides