Question

Not considering the electronic spin, the degeneracy of second excited state(n=3) of hydrogen atom is 9, while the degeneracy of second excited state of H-

Answer 1

Hi,

Hydrogen is one electron element. For one electron element like hydrogen the energy is governed by principal quantum number. For multi electron species it is governed by sum of principal and azimuthal quantum number.

For one electron element like hydrogen the energy is given by n (principal quantum number)

For multi electron species the energy is given by n + l

For n= 3, the degeneracy is 9, involving 3s ( 1 orbital) , 3p ( 3 orbital) and 3d (5 orbital). So total degeneracy for n = 3 is 9.

For H^- ion the second excited state is given by 2p orbital and its degeneracy is 3.

Regards