s-electrons and p-electrons [ENDORSED]

[Christy Lee 2H]

Can someone explain why s-electrons have a lower energy than p-electrons? Confused because their energy differs even though they're in the same shell??

[Rebecca Cheung 1E]

Because of the different shapes of s and p orbitals, in a multi-electron system the energy of s-orbitals is lower than the energy of p-orbitals because of the small differences in attraction they feel from the nucleus. S-orbitals is spherical and symmetrical with no nodal planes, while p-orbitals are non symmetric and have a nodal plane so they feel different pulls from the nucleus.

[skalvakota2H]

The idea is that since s-electrons do not have a node at the nucleus as opposed to p-electrons with nodes. This difference in shape allows for more electron penetration by the s-electrons. As a result, this decreases the shielding of the s-electrons, and getting closer to the nucleus adds more nuclear charge which lowers the energy. Thus, the energy of s-electrons is relatively lower to that of the p-electrons.