Single Electron System Orbital Question

[Gabriel Wolf 3I]

I was wondering why s orbitals in different energy levels are equivalent in energy in a 1 electron system (why does 1s = 2s if there is only 1 electron?). Also, why can't 1 electron systems have p orbitals?

[Carlotta Gherardi 2J]

Hi,

I think its because in a one electron atom like H there is no electron-electron repulsion nor any shielding, so the orbitals in the same shell (or energy level) have the same energy.

Instead, in multi electron atoms, there are more factors that affect the effective nuclear charge electrons feel. These electrons do feel the electrostatic attraction to the nucleus, but they also repel one another, and inner electrons shield outer electrons from the pull of the nucleus, leading them (and hence their orbitals) to being on slightly different energy levels.

Hope this helps!

[Carlotta Gherardi 2J]

Also, I think they can't have p orbitals because even if the atom's one only electron were to be excited to the second energy level (where p orbitals start being present), it would still occupy the 2s orbital which is before the 2p (to be more stable).