Question

$Zr(Z=40)$ and $Hf(Z=72)$ have similar atomic and ionic radii because of :

• A. Having similar chemical properties
• B. Belonging to same group
• C. Diagonal relationship
• D. Lanthanoid contraction

Answer 1

The correct option is D Lanthanoid contraction

• The cumulative effect of the contraction of the lanthanoid series, known as lanthanoid contraction, causes the radii of the members of the third transition series to be very similar to those of the corresponding members of the second series.
• The almost identical radii of $Zr\left(160pm\right)$ and $Hf\left(159pm\right)$ is a consequence of the lanthanoid contraction.