Question

The electronic configuration of actinides cannot be assigned with degree of certainty because of

• A. small energy difference between 5f and 6d levels
• B. overlapping of inner orbitals
• C. free movement of electrons over all the orbitals
• D. All of the above

Answer 1

Answer: (A)

small energy difference between 5f and 6d levels

Answer 2

Since, there is a very small difference between the energies of $5 f$ and $6 d$ levels, thus the electron can go to $6 d$ level or can remain in $5 f$ level. Hence, the electronic configuration of actinides cannot be assigned with degree of certainty.