s < p < d < f energies

[Hannah Cole 3J]

I don't understand how penetration and shielding effects lead to s < p < d < f energies, could someone please explain?

[Ryka Vahidi 1E]

The Penetration effect can be solved using the quantum numbers and formula. If you solve the formula, you will see that electrons in the s orbital have a high electron probability density near the nucleus, while f electrons have zero electron probability density near the nucleus, which is why the S orbital is near the nucleus and the F orbital is farther away. Furthermore, the shielding effect means that electrons in the S subshell repel the electrons in the P subshell, causing them to be further from the nucleus. Then, the P electrons repel the D electrons, and the D electrons repel the F electrons, causing there to be the different energy levels that we see.