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My understanding of orbital energies for multielectron atoms is that the principal quantum number determines the "ranking" of energies (e.g., every n=4 orbital is at a higher energy than a n<=3 orbital), and that for two different orbitals with the same n, the subshell determines the energy ranking (s<p<d<f).

Why then do electrons, in aufbau, go from 4s to 3d?

Also, when you add 2 electrons to Te to get Te2-, do the electrons go to the unfilled orbital of the lowest n (that is, do electrons go to 4f?)? What are the electron configuration rules for anions?

[Schrödinger]

n + l rule. http://www.citycollegiate.com/atomic_structureXI_EC02.htm