Order of removing electrons

[Isabel Day 1D]

Problem 1E.17 states: For each of the following ground-state atoms, predict the type of orbital from which an electron will be removed to form the +1 ion: (a) Ge; (b) Mn; (c) Ba

I don't understand the answer to (b). The solutions manual says it's 4s, but I thought it was 3d because 3d is filled after 4s and it's only half filled in the ground state of Mn. Why would an electron be removed from the 4s orbital before a half-filled 3d orbital?

[philipraj_1F]

The s orbitals are considered to be less stable for an electron than d orbitals once one electron is added to a d orbital. That is why you remove electrons from a s orbital before d orbitals.

[Quynh Vo]

4s is originally lower energy than 3d, but once 3d is filled, it becomes higher energy than 3d. Therefore the electron will be removed from 4s before 3d because electrons are removed from the higher energy orbital.

[mayarivers3I]

I was told that electrons are removed from the outer most shell, so it would make sense for 4s to be the orbital that the electron is removed from because thats the outer most orbital.

[Emil Velasco 1H]

Once 4s is filled, it has a higher energy than the 3d orbital, so the electrons removed are from 4s, the outermost shell.