Magnetic Spin

[William Chan 1D]

Do we need to know magnetic spin for the test? Also, why is it + or - 1/2, and not a whole number?

[Ellen Amico 2L]

I don't think it's something we really have to know for the test, since each electron has one of those spin numbers. Not totally sure on why it's +/- 1/2, but I think it's because of a theorem, which we definitely don't need to know. I would just remember that it exists and is a way of specifying a singular electron of an atom.

[Sebastian Lee 1L]

I think you should understand electron spin as it pertains to electron configurations of certain elements. For instance, the Pauli Exclusion Principle states that if 2 electrons are in the same orbital, they should have opposite spins (spin up and spin down). Hund's rule says that electrons in the same subshell occupy different orbitals with parallel spin. So if you have something like Carbon, you could know that both of the electrons in the 2p subshell have spin up in different orbitals.

Also I do have the same question about why the spin number is only +/- 1/2.

[KaitlynBali_4B]

One thing that I find interesting to note is that the discovery of these magnetic spins was a result of Schrodinger's realization that hydrogen's observed spectral lines did not have the frequencies that he predicted they would have. Two scientists later discovered this magnetic spin property, and realized that it takes into account the observed deviations.

[Sanjana K - 2F]

The magnetic spin is used in the context of the spin magnetic number (the fourth quantum number that you use to describe an electron), so it is somewhat important. We denote the spin with either a +1/2 or a -1/2, which means the electron either spins clockwise or counterclockwise. No 2 electrons in the same atom will have the same 4 quantum numbers, so if one orbital has 2 electrons, one of those electrons will spin clockwise and the other counterclockwise. I believe the spin number being +/- 1/2 is just referring to 1 out of the 2 electrons possibly present in the orbital. It's just a way to denote spin; don't worry too much about the actual 1/2 value.