Question

When electrons are added in the 6s orbital, what happens to the energy level of the 5d
orbitals? As a result after the electron enters 5d orbitals in the lanthanum, in which orbital
does the next electron enter in cerium?

Answer 1

When electrons are added in the 6s orbital, what happens to the energy level of the 5d orbitals? As a result after the electron enters 5d orbitals in the lanthanum, in which orbital does the next electron enter in cerium?

Answer:

There is a consistent increase in the number of electrons at the 4f level, and level 5d remains unoccupied. In cerium, at the 4f level, there are two electrons - one due to an increase in the sequence number as compared to lanthanum by one, and the other goes from 5d-level to 4f.