Filling electron shells [ENDORSED]

$sp, sp^{2}, sp^{3}, dsp^{3}, d^{2}sp^{3}$

Lourick Bustamante 1B
Posts: 50
Joined: Wed Nov 16, 2016 3:02 am

Filling electron shells

Why do certain orbitals get filled first even though the other orbitals have a smaller number? (for example, 4s fills before 3d)

Chem_Mod
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Joined: Thu Aug 04, 2011 1:53 pm
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Re: Filling electron shells  [ENDORSED]

As I discussed in class: for K and Ca the 4s is lower in energy than the 3d

AnuPanneerselvam1H
Posts: 52
Joined: Fri Sep 29, 2017 7:07 am

Re: Filling electron shells

The 4s orbital is filed first because it is lower in energy compared to the 3d orbital. The lowest energy state is always preferred. Another example of this is with the Chromium and copper examples. The electron in the 4s orbital will move to the 3d orbital in order to the evenly fill the orbitals, which contributes to a lower and more stable energy state.

Shreya Ramineni 2L
Posts: 50
Joined: Fri Sep 29, 2017 7:07 am

Re: Filling electron shells

4s is lower in energy than 3d, so it gets filled up first.