Question

why is the electronic configuration of lanthanum 5d^1 6s^2 and not 4f^1 6s^2?Why does that one electron jump from f orbital to d orbital?

Answer 1

This is actually the exception in our common rule of writing the electronic configuration. Reason for this exception is that electron occupy the most stable electronic configuration in their ground state. This means that we fill the lowest energy levels first.In Lanthanum, the empty 5d sublevel has lower energy than the 4f sublevel, Hence Lanthanum [Xe] 5d1 6s2 instead of [Xe] 6s2 4f1.

Answer 2

Explanation:

the electronic configuration of lanthanum 5d^1 6s^2 and not 4f^1 6s^2?Why does that one electron jump from f orbital to d orbital.