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Homework Help: Which one of the following orbitals is lowest in energy in a Li2+ ion?

  1. Nov 13, 2012 #1
    Which one of the following orbitals is lowest in energy in a Li2+ ion?

    12p z
    2d x^2-y^2
    5f xyz
    4d xz

    attempt on solution:

    l=can be n-1
    ml=-l to + l
    Therefore the lowest energy is

    I suppose the answer is 12p z? since the l can be any number smaller than 3 until zero. I am not sure, but the answer is 4d xz
  2. jcsd
  3. Nov 13, 2012 #2


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    Gold Member

    Use Aufbau Principle. I am sure you know how to draw the diagram, that diagonal arrows one.

    By common sense, 12(!) shell is absurd in comparison to 4th and 5th shell given.
  4. Nov 14, 2012 #3


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    Staff: Mentor

    I don't think Aufbau principle is a good approach, we are talking about a single electron and Aufbau principle assumes all lower energy orbitals are already filled. In this particular case it doesn't matter, but in general it is guaranteed to give bad results in some cases (think 4s and 3d).

    For an electron in a hydrogen-like atom energy is a function of only one quantum number. Do you know which one?
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