## Electron Configurations and Unpaired e- [ENDORSED]

Chris Fults 1C
Posts: 27
Joined: Wed Nov 15, 2017 3:01 am

### Electron Configurations and Unpaired e-

Hello, I am confused on how to determine the number of unpaired electrons. For example, the electron configuration for Se is [Ar] 3d^10, 4s^2, 4p^4. Because there are 4 electrons in the p-orbital doesn't that mean that all 4 are unpaired as they first go in separate shells then fill in the boxes with 2 each?

Posts: 30
Joined: Fri Apr 06, 2018 11:03 am
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### Re: Electron Configurations and Unpaired e-

There would be 2 unpaired electrons because the p-orbital can hold 6 electrons total. You would first begin by putting the 3 electrons as unpaired but then there is still 1 electron left which you would place with one of the first 3 single electrons. Thus there would be 1 pair and 2 unpaired electrons.
Hope this helps

Posts: 30
Joined: Fri Apr 06, 2018 11:02 am

### Re: Electron Configurations and Unpaired e-  [ENDORSED]

According to Hund's rule, every orbital in a sublevel has to be occupied before placing the rest of the leftover electrons. Therefore the p suborbital can hold 6 electrons in total and has 3 orbitals. Since there are 4 electrons that will occupy the p-suborbital, you will each place one electron in the 3 orbitals and pair the fourth electron with one of the recently placed electrons. Therefore, you will have 2 unpaired electrons. Hope I explained well!

Tiffany Tufenkjian 1E
Posts: 30
Joined: Fri Apr 06, 2018 11:05 am

### Re: Electron Configurations and Unpaired e-

There are 3 orbitals total that each hold two electrons (so 6 total) for p. The first 3 electrons are evenly distributed in the 3 orbitals and then the fourth is paired in the first orbital. This leaves two orbitals with unpaired electrons.