## Electron Arrangements

Frederick Keith_4C
Posts: 65
Joined: Thu Sep 26, 2019 12:19 am

### Electron Arrangements

If 2 electrons are paired then they have opposite spin and if 2 electrons are parallel then they have the same spin. But how do you know if the electrons are paired or parallel when writing out the electron arrangements given only and element's atomic number principal energy level?
For example, if I told you that Boron (element 5) was at n=2, how would you be able to draw its electron arrangement?

Mariepahos4D
Posts: 50
Joined: Sat Sep 07, 2019 12:19 am

### Re: Electron Arrangements

For boron the electron configuration is 1s2 2s2 2p1
So in the 1s orbital you would have 2 electrons with opposite spin, in the 2s orbital you would again have 2 electrons with opposite spin and in the 2p orbital you would have 1 electron. If, for example you had an element with 2p5 you would have 2 pairs of paired electrons with opposite spin and one electron unpaired. You first fill in electrons that are unpaired ( paralell) and then go back and pair electrons with the remaining needed.