From which sublevel are the first 2 electrons for Fe removed from ______

Question

From which sublevel is the next electron for Fe removed from _________
Why does the removal of electrons stop at this subleval and number of electron??
Please help me !!!

Answer 1

Fe is 1s2 2s2 2p6 3s2 3p6 3d6 4s2.
So the first 2 e come from the 4s level. The next 6 (one at a time) would come from the next lower level. which one is that?
It stops at 3 because the configuration then is
1s2 2s2 2p6 3s2 3p6 3d5. One reason is that the 3d level at half filled is stable. A second reason is that with a +3 ion, it is almost impossible to pull another electron off and overcome the attractive forces between that last electron and the +3 charge of the nucleus.

Answer 2

thank you