Question

Actinides exhibit larger number of oxidation state than that of corresponding lanthanides. The reason behind this aspect is

• A. larger atomic size of actinides than the lanthanides
• B. lesser energy difference between $5f$ and $6d$ -orbitals than between $4f$ and $5d$-orbitals.
• C. more energy difference between $5f$ and $6d$ orbitals than between $4f$ and $5d$-orbitals
• D. greater reactive nature of the actinides than the lanthanides

Answer 1

The correct option is B lesser energy difference between $5f$ and $6d$ -orbitals than between $4f$ and $5d$-orbitals.

Actinides exhibit larger number of oxidation state than that of corresponding lanthanides because of the almost similar energy of the actinides, they have more contraction than that of lanthanides due to the poor shielding effect of $5f$ orbitals than that of $4f$. So, there is lesser energy difference between $5f$ and $6d$-orbitals as compared to between $4f$ and $5d$-orbitals.