Question

Reason of lanthanoid contraction is ______.

Options

• negligible screening effect of ‘f’ orbitals.

• increasing nuclear charge.

• decreasing nuclear charge.

• decreasing screening effect.

Answer 1

Reason of lanthanoid contraction is negligible screening effect of ‘f’ orbitals.

Explanation:

Lanthanoid contraction refers to the gradual decrease in atomic and ionic sizes of lanthanoids from Ce to Lu. This happens because the 4f orbitals have a poor (negligible) shielding effect, so the increasing nuclear charge pulls the electrons closer to the nucleus.