Spin State

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Nick Fiorentino 1E
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Joined: Wed Sep 18, 2019 12:16 am

Spin State

Postby Nick Fiorentino 1E » Thu Oct 17, 2019 9:57 am

What do the +1/2 and -1/2 mean with regards to spin state? Is it the direction in which the electron spins? And how would the spin state be determined?

005391550
Posts: 103
Joined: Thu Jul 25, 2019 12:15 am

Re: Spin State

Postby 005391550 » Thu Oct 17, 2019 10:41 am

+1/2 refers to spin up and -1/2 refers to spin down because an electron can either be spin up or spin down. don't know how it would be determined tho

Fatemah Yacoub 1F
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Re: Spin State

Postby Fatemah Yacoub 1F » Thu Oct 17, 2019 11:29 am

Calculating spin state is not necessary as it will always be either +1/2 or -1/2. The positives and negatives simply represent whether the electron is spinning clockwise or counterclockwise

Audrie Chan-3B
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Joined: Thu Jul 25, 2019 12:17 am

Re: Spin State

Postby Audrie Chan-3B » Thu Oct 17, 2019 11:29 am

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.

Kallista McCarty 1C
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Re: Spin State

Postby Kallista McCarty 1C » Thu Oct 17, 2019 1:43 pm

Spinning up is referred to as +1/2 while spinning down is represented as -1/2

Megan Ngai- 3B
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Joined: Fri Aug 09, 2019 12:17 am

Re: Spin State

Postby Megan Ngai- 3B » Thu Oct 17, 2019 2:16 pm

Spinning up is positive (+1/2)
Spinning down is negative -1/2

Daria Azizad 1K
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Re: Spin State

Postby Daria Azizad 1K » Thu Oct 17, 2019 2:30 pm

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).

Manav Govil 1B
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Joined: Sat Sep 07, 2019 12:19 am

Re: Spin State

Postby Manav Govil 1B » Thu Oct 17, 2019 3:57 pm

A +1/2 spin is spinning up, while a -1/2 spin is spinning down. Remember, this is not like the electron is spinning north or south if it is spinning up or down. They are spinning in different directions. That's about it.

Nathan Nakaguchi 1G
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Re: Spin State

Postby Nathan Nakaguchi 1G » Thu Oct 17, 2019 4:22 pm

+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.

Jamie Hwang 2F
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Re: Spin State

Postby Jamie Hwang 2F » Fri Oct 18, 2019 12:22 am

If we have a full shell, what would the quantum number be? Do they cancel each other and it is zero (that doesn't really make sense) or is it just the last spin state (+ or - 1/2)?

Rory Simpson 2F
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Joined: Fri Aug 09, 2019 12:17 am

Re: Spin State

Postby Rory Simpson 2F » Fri Oct 18, 2019 12:36 am

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.

Yiyang Jen Wang 4G
Posts: 76
Joined: Wed Nov 21, 2018 12:18 am

Re: Spin State

Postby Yiyang Jen Wang 4G » Fri Oct 18, 2019 2:21 am

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.

Chantel_2I
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Joined: Sat Sep 07, 2019 12:19 am

Re: Spin State

Postby Chantel_2I » Fri Oct 18, 2019 11:00 am

A +1/2 electron and a -1/2 electron would react differently when exposed to a magnetic field. This number differentiates between the two electrons, but it doesn't literally mean that they are moving in a specific direction.

Ruby Richter 2L
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Joined: Thu Jul 25, 2019 12:17 am

Re: Spin State

Postby Ruby Richter 2L » Fri Oct 18, 2019 3:30 pm

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.

KBELTRAMI_1E
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Joined: Sat Jul 20, 2019 12:17 am

Re: Spin State

Postby KBELTRAMI_1E » Fri Oct 18, 2019 4:14 pm

Let's talk about spin. What is even going on and how do we know if it's positive or negative?

Brittany Tran 3I
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Joined: Sat Jul 20, 2019 12:16 am

Re: Spin State

Postby Brittany Tran 3I » Fri Oct 18, 2019 4:14 pm

the positive and negative values are arbitrary. generally, the electron with +1/2 will be the arrow that's pointed upwards, and the electron with -1/2 will be the arrow that's pointed downwards, just for notation

Jason Wu 1E
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Re: Spin State

Postby Jason Wu 1E » Fri Oct 18, 2019 4:19 pm

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.

chrischyu4a
Posts: 52
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Re: Spin State

Postby chrischyu4a » Fri Oct 18, 2019 6:56 pm

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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