## Electron configuration

Marina Souliman 1K
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### Electron configuration

Why do we add parallel spins to different orbitals if there are more than 2 orbitals in a subshell?

Priscilla Okaiteye
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Joined: Tue Nov 21, 2017 3:02 am

### Re: Electron configuration

For subshells with more than one orbital we fill each on with one electron before coming back to add the second electron. This all the single electrons in the subshell will be rotating in the same direction making them parallel. When you add the second electron to the subshells the mush rotate in opposite directions.
I wish I could add an image to explain better, but I hope this helps. It's just a logical observation.

megangeorge-1K
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### Re: Electron configuration

in class we had an example of writing the electron configuration of Calcium and we were able to write it as: [Ar]4s^2... why are we able to use Argon to write the electron configuration?

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### Re: Electron configuration

megangeorge-1F wrote:in class we had an example of writing the electron configuration of Calcium and we were able to write it as: [Ar]4s^2... why are we able to use Argon to write the electron configuration?

Argon is the noble gas before Calcium. Argon has a full valence shell, so using Argon summarizes the electron configuration up to Argon itself. Afterwards we only have to account for the electron configuration until it satisfies Calcium.

Chem_Mod
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### Re: Electron configuration

Having parallel spins in orbitals having same n and l but different ml (for example 2px and 2py) is beneficial because electrons with parallel spins automatically avoid each other and therefore repel each other less.

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### Re: Electron configuration

According to Hund's Rule, due to electron repulsion, electrons in the same sub-shell occupy different orbitals with parallel spin.

Marina Souliman 1K
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Joined: Fri Apr 06, 2018 11:05 am

### Re: Electron configuration

This clears up a lot! Thank you!

Another quick question though for clarification. I know that paired electrons have opposite spins but why do they have opposite spins? Is it due to their charge or is it because no two electrons can have the same four quantum numbers or because of something else?

I'm not sure if that was covered in class and I didn't catch it.

megangeorge-1K
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Joined: Thu Feb 01, 2018 3:01 am

### Re: Electron configuration

Marina Souliman 1K wrote:This clears up a lot! Thank you!

Another quick question though for clarification. I know that paired electrons have opposite spins but why do they have opposite spins? Is it due to their charge or is it because no two electrons can have the same four quantum numbers or because of something else?

I'm not sure if that was covered in class and I didn't catch it.

hello! I'm not really sure how helpful my response will be lol
in lecture, Dr. Lavelle said that according to Hund's rule: due to electron repulsion, electrons in the same subshell must occupy different orbitals with parallel spins allowing for the lowest energy.

Chem_Mod
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### Re: Electron configuration

No two electrons can have the same four quantum numbers, so if two electrons are in the same orbital, they must have opposite spins (paired). These two electrons have the same value for n, l, and ml, but not ms because they have opposite spins.