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Homework Help: Orbital overlap diagram for ammonia

  1. Oct 3, 2017 #1
    1. The problem statement, all variables and given/known data

    Drawn an orbital overlap diagram to represent the bonding in ammonia, NH3.

    2. Relevant equations


    3. The attempt at a solution

    I learned that bonding occurs with the outermost s and p orbitals.

    For nitrogen:
    1s2 , 2s2 , 2p3

    For Hydrogren:
    1s1 X 3.

    This is what I drew


    Someone told me to think about the Pauli Exclusion Principle and that my diagram is incorrect because of some of the spin states in the orbitals. The Pauli Exclusion Principle states that each orbital can old 2 electrons. If two electrons are in the same orbital they must have opposite spins. In my diagram, any orbital that has two electrons has opposite spins, so I am not sure what the person was telling me.

  2. jcsd
  3. Oct 3, 2017 #2


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    Science Advisor
    Gold Member

    As long as this is true, I think you're probably fine. These orbital overlap things weren't around when I was doing this level of chemistry, so I'm not really sure what people look for in a correct answer.
  4. Oct 3, 2017 #3
    The other person helping me also said that they have never heard of orbital overlap diagrams.
    I'm pretty sure it is correct but just wanted to double check, thanks!
  5. Oct 3, 2017 #4


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    Staff: Mentor

    No idea what it is all about, but in your picture there are six electrons with identical spin - as they should fit three orbitals, perhaps there should be three [itex]\uparrow[/itex] and three [itex]\downarrow[/itex]?
  6. Oct 3, 2017 #5
    I thought that the Pauli Exclusion Principle only applied to electrons are in the same "circle"?

    Maybe my diagram is a bit confusing. The three "circles" to the right of 2p are all 2p orbitals while the 1s orbitals above and below are supposed to be the 1s hydrogen orbitals bonding to the 2p nitrogen orbitals. I can try to draw a new diagram if mine doesn't make sense. This is how we were taught to draw them but I still don't really understand it.
  7. Oct 3, 2017 #6


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    Staff: Mentor

    s and p electrons from different atoms, if they are to land on a single bonding orbital (that would be σ bond) need to have opposite spins. This is a simple conclusion of the exclusion principle, it is obligatory for every orbital (ie you can't create a bonding or antibonding orbital from electrons with the same spin).

    As I understand the diagram it doesn't really show bonding orbitals, just the possibility of their creation, so it shouldn't matter much, but using electrons with opposite spins will make the diagram a bit more "realistic".
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