## Electron Spin Quantum Number [ENDORSED]

(Polar molecules, Non-polar molecules, etc.)

Stef Newell
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Joined: Fri Sep 29, 2017 7:04 am

### Electron Spin Quantum Number

What values can the electron spin quantum number (ms) have?

Nishma Chakraborty 1J
Posts: 51
Joined: Fri Sep 29, 2017 7:04 am

### Re: Electron Spin Quantum Number  [ENDORSED]

Hi!
The electron spin quantum number (ms) can have values of +1/2 or -1/2. Hope this helps!

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

### Re: Electron Spin Quantum Number

The electron spin number can be either +1/2 or -1/2. This just tell us whether the electron is spinning clockwise or counterclockwise.

Grace Ramey 2K
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Joined: Thu Jul 27, 2017 3:01 am

### Re: Electron Spin Quantum Number

I have a follow-up question. How is the spin of an electron (either +1/2 or -1/2) determined? Does the first electron to fill an orbital automatically have a +1/2 spin since we always represent it using an upwards arrow when writing out the electron configuration? Or is there no way to tell the exact spin?

Nishma Chakraborty 1J
Posts: 51
Joined: Fri Sep 29, 2017 7:04 am

### Re: Electron Spin Quantum Number

Hey!

To follow up, the direction of the first electron is always represented by an arrow drawn facing upwards (which signifies that the first electron has the +1/2 spin. The electron following is represented by an arrow pointing downwards because it has a negative +1/2 spin. This aforementioned is in reference to Pauli's Exclusion principle. Hund's Rule also states that all electrons in an orbital are first filled by the +1/2 sign. I hope this made sense, but if not, I found this neat article that explains some of the stuff in more detail (and with visuals). :) Here's the link:

https://chem.libretexts.org/Core/Physic ... ctron_Spin

Rachel Min
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Joined: Fri Sep 29, 2017 7:04 am

### Re: Electron Spin Quantum Number

I'm still confused about how exactly we (or whoever came up with this quantum number) got the numbers -1/2 and +1/2 to describe electron spin. Is there a more conceptual reason behind it? Or did some kind of math just work out like that?

Chem_Mod
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### Re: Electron Spin Quantum Number

When Professor Lavelle discussed spin in class, he mentioned that the beam of silver atoms, when exposed to a strong magnetic field, split into two beams, which established the basis of our understanding of spin. Different sub-atomic particles have either integer or half-integer values of plank's constant for spin, which is related to the solutions to the schrodinger equation for the wavefunction of that particle which is beyond the scope of this class, but for more information to curb your curiosity perhaps check out this article https://www.scientificamerican.com/arti ... -the-spin/, the wikipedia page for spin,https://en.wikipedia.org/wiki/Spin-%C2%BD, or other resources in the Science and Engineering Library.

Rachel Min
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### Re: Electron Spin Quantum Number

Thank you! This really helped!

Kaelie Blanes-Ronda 2L
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### Re: Electron Spin Quantum Number

The spin quantum numbers can only be 1/2 or -1/2.

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

### Re: Electron Spin Quantum Number

the quantum spin number can haven either +/- 1/2.

mayasinha1B
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Joined: Fri Sep 29, 2017 7:04 am

### Re: Electron Spin Quantum Number

Electrons also fill each orbital in a subshell all with spin facing a certain direction (either +/- 1/2) before refilling the orbitals with the opposite spin.

Daniel Rivas 3L
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Joined: Fri Sep 29, 2017 7:07 am

### Re: Electron Spin Quantum Number

It can be either 1/2 or -1/2.