Question

How do lanthanoid contraction affect the following property of the elements placed after lanthanoids?

Densities.

Answer 1

1. Lanthanoid contraction causes a decrease in atomic and ionic sizes across the lanthanoids due to poor shielding by 4f electrons, increasing effective nuclear charge.
2. This size reduction leads to a significant increase in the density of elements placed after the lanthanoids, especially in the third transition series.
3. As a result, elements following lanthanoids have abnormally higher densities compared to their immediate lighter homologues.
4. For example, third-row transition metals show nearly double densities of the second-row elements in the same groups due to lanthanoid contraction.
5. This abnormal increase in density is directly linked to the reduced atomic size caused by lanthanoid contraction.