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Homework Help: GRE question - atomic physics

  1. Oct 18, 2007 #1
    1. The problem statement, all variables and given/known data

    The ground state electron configuration for phosphorus, which has 15 electrons, is

    • 1s^2 2s^2 2p^6 3s^1 3p^4
    • 1s^2 2s^2 2p^6 3s^2 3p^3
    • 1s^2 2s^2 2p^6 3s^2 3d^3
    • 1s^2 2s^2 2p^6 3s^1 3d^4
    • 1s^2 2s^2 2p^6 3p^2 3d^3

    2. Relevant equations

    3. The attempt at a solution

    No clue.
  2. jcsd
  3. Oct 18, 2007 #2


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    We can not help you unless you show us some effort/thought/ideas...anything! What have you tried so far?
  4. Oct 18, 2007 #3
    I've tried looking up to see what all those numbers mean, but I couldn't find any info. It's not in the physics book I have (Ohanian).
  5. Oct 18, 2007 #4
  6. Oct 18, 2007 #5
    tbh, you could probably work this one out with almost no physics/chemistry knowledge. If you looked at it as a sequence, (provided you know what the groundstate means), you should be able to get it.
  7. Oct 18, 2007 #6
    You would at least have to now what sublevels "s", "p", "d" and "f" are. And you'd have to now the number of orbitals and the maximum number of electrons each can have.
  8. Oct 18, 2007 #7


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    Bill, that's correct. If you still have trouble with this look up the Aufbau Principle.
  9. Oct 19, 2007 #8


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    Fortunately, he was only asked to find the configuration for phosphorus. Aufbau only gets you so much mileage -- the simple picture starts to break down when the atomic number gets to the mid-20s (the iron group elements)...
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