What is lanthanide contraction? Write any two of its consequences.

Explanation

Lanthanoid contraction The overall decrease in atomic and ionic radii from lanthanum to lutetium, due to the imperfect shielding of one electron by another in the same subshell, is known as lanthanide contraction. (1) Consequences of lanthanide contraction, are as follows :
(i) Due to lanthanoid contraction, the basic character of oxides and hydroxides decreases from `La(OH)_(3)` to `Lu(0H)_(3)`
(ii) Elements of second and third d-series exhibit similar radii (e.g. Zr-160 pm, Hf-159 pm) and have very similar physical and chemical properties,