Q. More number of oxidation states are exhibited by the actinoids than by the lanthanoids. The main reason for this is :
A) more energy difference between 5f and 6d orbitals than that between 4f and 5d orbitals
B) lesser energy difference between 5f and 6d orbitals than that between 4f and 5d orbitals
C) greater metallic character of the lanthanoids than that of the corresponding actinoids
D) more active nature of the actinoids
Explanation
[Solution from source] In actinoids the 5f, 6d and 7s orbitals are very close in energy, closer than 4f, 5d and 6s in lanthanoids, and 5f electrons are less tightly held. So more electrons can take part in bonding, giving many more oxidation states. A larger 5f–6d gap would have the opposite effect. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.