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Homework Help: Which electron configuration is not possible for As? Don't know much about spdf orbit

  1. Oct 8, 2008 #1
    11. Which one of the following sets of quantum numbers (n, l, ml, ms) could not possibly describe one electron of an arsenic atom (Z = 33) in its ground state?

    (A) 2, 1, -1, 1/2
    (B) 4, 2, 2, -1/2
    (C) 3, 0, 0, -1/2
    (D) 3, 2, -2, 1/2
    (E) 4, 1, 0, 1/2

    Solution:

    Electron configuration for arsenic:
    1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3

    2, 1, -1, 1/2 represents a 2 p electron, possible.
    4, 2, 2, -1/2 represents a 4 d electron, NOT possible for As.
    3, 0, 0, -1/2 represents a 3 s electron, possible.
    3, 2, -2, 1/2 represents a 3 d electron, possible.
    4, 1, 0, 1/2 represents a 4 p electron, possible.

    **********************

    I don't understand why its the second one, I do know that all of the numbers are allowed for n, l, ml, ms, but i dont understand how it changes when the element As comes into play.

    Thanks for any help
     
  2. jcsd
  3. Oct 9, 2008 #2

    Borek

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    Staff: Mentor

    Re: Which electron configuration is not possible for As? Don't know much about spdf o

    Does As have electrons on 4d when in ground state?
     
  4. Oct 9, 2008 #3
    Re: Which electron configuration is not possible for As? Don't know much about spdf o

    Oh ok, that's what i didn't understand in quantum numbers, l of 2 indicates a d orbital, but as has no electrons in a d orbital in ground state. thx
     
  5. Oct 9, 2008 #4

    Borek

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    Staff: Mentor

    Re: Which electron configuration is not possible for As? Don't know much about spdf o

    Yes it has - but on 3d, not 4d.
     
  6. Oct 9, 2008 #5
    Re: Which electron configuration is not possible for As? Don't know much about spdf o

    Sorry, yea, thats what i meant, thx
     
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