Spin Up and Spin Down

[Nigah Fatima]

I am still confused on what exactly spin up and spin down quantum number means. I understand how spin up means +1/2, while spin down means -1/2. However, I don't understand what spin up and spin down mean itself. If someone could explain what exactly this means and how this relates to the spin quantum numbers, that would be greatly appreciated.

[KPINTO 1B]

Well I believe the 1/2 is the magnitude of the spin and the + or - is the direction, so essentially the m sub s quantum number is a vector that describes what the electron is doing in the location it is in which is discovered through the n, l, and m sub l.

[Tomas Burgess 3F]

Hi! Spin up and spin down refer to the angular momentum of an electron. The fact that electrons spin around the nucleus on an axis means that each electron has angular momentum, and we denote the 2 possible angular momentum vectors as "spin up" and "spin down." The 1/2 is just a constant for the magnitude of the angular momentum. Finally, we know there are 2 angular momentum vectors because a single atomic orbital can hold a maximum of 2 electrons, and a full orbital's 2 electrons will spin in different directions (so in every full orbital, one electron will have a spin quantum number of +1/2 and the other will have -1/2).

[Molly McAndrew 1 1H]

If an electron's orbital holds two electrons, will one always spin up and one spin down? And what if there are more or less electrons in an orbital... is that even possible?

[Hannah Jin 1J]

If an electron's orbital holds two electrons, will one always spin up and one spin down? And what if there are more or less electrons in an orbital... is that even possible?

An orbital can only have a maximum of 2 electrons, and according to the Pauli Exclusion Principle, those 2 electrons in the same orbital will never spin the same way.

[Tess_Fleser_1D]

From what I learned in high school chem, when there is a full valence shell there will be the same amount of electrons spinning in each direction, so in a p orbital of 6 electrons, there will be 3 spinning down and 3 spinning up for balance.

[905740390]

The spin up and down gives us the angular momentum. The 1/2 value gives us the magnitude and the + or - gives us direction. Additionally, an orbital can only have up to 2 electrons and one will face in the positive direction and the other in the negative according to the Pauli Exclusion Principle.

[Claire Kim 1F]

I am still confused on what exactly spin up and spin down quantum number means. I understand how spin up means +1/2, while spin down means -1/2. However, I don't understand what spin up and spin down mean itself. If someone could explain what exactly this means and how this relates to the spin quantum numbers, that would be greatly appreciated.

Hi, I believe the +1/2 and -1/2 represents the spin of the electrons in an orbital. To put this into context, there's 2 arrows in a full orbital so one would stand for +1/2 and the other would stand for -1/2.

[14b_student 2E]

Will there always be the same amount spinning up as there are spinning down?

[Arya Bhalla 1H]

In high school I learned that a spin up represents the electron rotating counterclockwise while spin down represents the electron rotating clockwise. Although I don't know how accurate this is considering how small electrons are and whether they can actually rotate in a particular direction. As far as the value of 1/2 goes, it might be arbitrary or it might have some other mathematical significance. Not too sure about that specifically but it would definitely be fascinating to know if anyone has an idea.

[Cecilia Lei 3K]

The direction of spin is determined by the sign of 1/2. + means spin up and - means spin down. The reason why electrons are opposite in spin in one orbital is that electrons repel each other in one orbital. Actually, when filling orbitals in the same block, electrons tend to occupy empty orbitals first rather than occupying the orbital that already has one electron.