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Hund's Rules

  1. Jan 6, 2016 #1
    I have the solution for this problem but don't understand it.

    1. The problem statement, all variables and given/known data

    Use Hund's rules to calculate the ground state of erbium with electron configuration [Xe]4f126s2

    2. Relevant equations
    Hunds Rules:
    1. Maximise S (within Pauli)

    2. Maximise L (within Pauli)

    3. Min J (for less than half-filled orbitals) or Max J (for more than half-filled orbitals)

    3. The attempt at a solution
    So I used these rules on the 12 electrons in unfilled f orbital and I arrived at S=1, L=5, and therefore J=S+L=6 but the solution which I have been given is: S=3, L=9, J=12

    Can anyone confirm if the solution is correct and where I am going wrong?

  2. jcsd
  3. Jan 6, 2016 #2


    User Avatar

    Staff: Mentor

    Your solution is correct.

    For more than half-filled shells, it is easier to work with holes than with electrons: f12 and f2 generate the same terms. That will tell you quickly what the solution is.
  4. Jan 6, 2016 #3
    Great, thanks. And cheers for the tip, the holes method is much quicker!
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