Clarification about orbital angular momentum

[Amy Jordan 2A]

Hi, I just wanted some clarification about a section in the textbook about the orbital angular momentum in hydrogen. The textbook states in section 1D that "The orbitals of a shell in a hydrogen atom are said to be degenerate, which means that they all have the same energy. This degeneracy of orbitals with the same value of n but different values of l is true only of the hydrogen atom and one-electron ions." I'm having a hard time understanding this, and is this a significant piece of information? Thank you

[Coline Luo 2E]

Hi! I think what the book means is that, since there are no other electrons to provide shielding effects within the p, d, and f orbitals, the orbitals in hydrogen and one-electron atoms have the same energy. This is probably not super significant right now since it deals with shielding and electron-electron repulsion, which we are only learning about conceptually for now. Hope this helps!

[Erika Li 1E]

Hi! I think what that statement can be interpreted as is that, for hydrogen atoms (and one-electron ions), orbitals in a particular shell (corresponding to a principle quantum number n) will all have the same energy. For instance, the 2s orbital is the same energy as the 2p orbitals for hydrogen. However, for many-electron atoms, the presence of more than one electron changes the energies of the orbitals due to electron-electron repulsion. For instance, the 2s orbital is lower in energy than the 2p orbitals for many-electron atoms, which is why electrons will fill the 2s orbital before filling the 2p orbitals. The textbook probably mentioned that to distinguish the difference between one-electron and many-electron atoms. Hope this helps!