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The direction the electron spins in depends on whether its positive or negative 1/2. Typically, positive means spinning right while negative spins left. You can find it through the up and down arrows when determining electron configuration.
I think the way that spin numbers are determined is experimentally based on which way they interact with a magnetic field. However, the way we denote spin numbers in a full shell is by having one up and one down (to indicate that they go opposite directions to minimize repulsion).
+1/2 refers to spin up and -1/2 refers to spin down. I believe it is a reference to what would happen if you performed an experiment similar to the one Dr. Lavelle showed in lecture Oct 16th (the silver atoms one). Some electrons end up going upwards after going through a magnetic field while some others go down.
The total magnetic spin for the shell would add up to zero if it was full. Because of the Pauli exclusion principle (in that no two electrons can have the same exact quantum number configurations), an atom would need paired electrons with a positive and negative spin value in an full orbital.
There's no universal notion of "up" or "down", they just represent the two directions. +/- is just for you to distinguish the difference between the two paired electrons. I believe it does not really matter which is which.
KBELTRAMI_4I wrote:Let's talk about spin. What is even going on and how do we know if it's positive or negative?
The spin is determined by how many other electrons are in the outermost subshell of the atom. If the subshell is less than half-filled, then electrons with positive spin will fill out the subshell until it is half-filled. If the subshell is more than half-filled, then electrons with negative spin will fill out the subshells until all the orbitals in the subshell are full. An exception comes when electrons from a higher s/d orbital may be used in a lower energy state to first fill out a lower energy state d or f orbital if it is 1 electron away from being half-filled or full.
Ruby Richter 4G wrote:Do the positive and negative values relate to the arrows he draws in class? I'm confused as to how that relates to the spin state.
The positive and negative values don't necessarily correlate to a certain direction such as "up" or "down" that most people refer to, it just conveys the fact that electrons will either spin one way along an axis or the opposite way along the same axis. And yes, the arrows he drew in class are a basic representation of what the positive and negative values mean.
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