Spin Number (Ms)

[ZachMoore1C]

How does one calculate the spin quantum number?

[Alicia Yu 1A]

The spin quantum number tells us the spin of the electron and is the fourth quantum number. There can only be two electrons in an orbital (Pauli's exclusion principle) and the values for ms are +1/2 and -1/2.
Since electrons spin on its axis, it has both angular momentum and orbital angular momentum, Ms describes the angular momentum of the electron. The direction of the e- is indicated by (+,-) (arrows up or down).

[ZachMoore1C]

I understand what the spin number is and how it can only hold two values -1/2 and 1/2. I am just curious to know how to tell what the value the electron takes is. Is it only possible to tell through experimentation (the magnetic field experiment discussed in lecture) or is there a way to tell from the other quanta?

[Chem_Mod]

I understand what the spin number is and how it can only hold two values -1/2 and 1/2. I am just curious to know how to tell what the value the electron takes is. Is it only possible to tell through experimentation (the magnetic field experiment discussed in lecture) or is there a way to tell from the other quanta?

We won't really be able to know which electron spin in what direction. The only information we know is that the two electrons in the same orbital have different spins. You can think of it as assigning a "name" to those electrons.