CHEMISTRY COMMUNITY

How do you determine if an electron will spin up or spin down?

When you draw the electron configuration, it will determine if the electron is spin up or down.

I don't think it matters for unpaired electrons; it just says that paired electrons should have the opposite spin numbers.

Does that mean that when doing configurations it doesn't matter if we choose clockwise or counterclockwise spin for single electrons? Or is there a preference?

Generally, according to Hund's Rule, electrons in the same subshell occupy different orbitals with parallel spin due to their repulsion to each other. So more commonly, you can fill in electron configurations first with the spin up electrons until all orbitals are filled, then fill in with spin down electrons. However, you can also do this starting with spin down electrons. Just be sure you are applying Hund's Rule when doing so.

Matthew Regner 3C wrote:Does that mean that when doing configurations it doesn't matter if we choose clockwise or counterclockwise spin for single electrons? Or is there a preference?

Usually, you fill the electron configurations by starting with "spin up." However, you can also start with "spin down" as long as Hund's Rule is valid.