Atomic Structure

[Alex Nguyen 3I]

I think that single electron systems only have degenerate energy levels for orbitals/wavefunctions with the same principal quantum number. Therefore for multi-electron systems, different subshells have different energy levels. If this comes from the quantum number l, how does angular momentum affect energy level?

[Alex Nguyen 3I]

Does it have something to do with the idea that the p state has the potential to hold more electrons than s and so on?

[Chem_Mod]

Because the p-electron is shielded by the s-electron, the p-electron is less attracted to the nucleus and has a higher energy.

If there were only a single electron, the energies of ns and np would be the same. But this degeneracy is broken as soon as there are two or more electrons. This is because the potential function in the Hamiltonian has changed. The same kind of wavefunction is still a solution to the Schrodinger equation, but it now has different energy from before.