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Homework Help: Total angular momentum quantum number

  1. Aug 23, 2008 #1
    lets say there is an electron configuraiton of [tex]1s^2 2s^2 2p^2 3p^1[/tex]

    I want to find the total angular momentum quantum number, J=L+S

    considering the n=1 state, there are two electrons, in the s shell which means one is spin 1/2 and the other is spin -1/2 giving a total spin of 0. The s shell has no angular momentum so L=0.

    considering n=2 state, there are two electrons in the s shell which again gives us 0 total angular momentum. If we went to the p shell, there are 2 electrons in the p shell, each having L=1, so we add them together to get L=2. The two electrons do not contribute spin since their net sum is zero, S=1/2-1/2=0.

    considering the n=3 state, there is 1 electron in the p shell, which means S=1/2 and L=1

    J is the sum of L and S, so the total angular momentum should be J=L+S=2+1+1/2=7/2

    Is this correct?
  2. jcsd
  3. Aug 24, 2008 #2
    any ideas?
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