Unlocking Quantum Numbers for Lithium Atom

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For the lithium atom with atomic number Z = 3, the first two electrons occupy the lowest energy state with quantum numbers {1,0,0,+1/2} and {1,0,0,-1/2}. The third electron must occupy the next available energy level, which is n=2, with quantum numbers {2,0,0,+1/2}. The discussion highlights that the first shell is full, confirming that the third electron will be in the second shell, still in the s orbital (l=0). There is confusion about the preference for spin states, but it is clarified that both spin states should be included in the final answer. The correct set of quantum numbers for the third electron is thus {2,0,0,+1/2} or {2,0,0,-1/2}, depending on the context of the question.
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Homework Statement



Lithium has an atomic number Z = 3. Two of its electrons have the quantum numbers {n, L, m{l}, m{s}} = {1,0,0,+1/2} and {1,0,0,-1/2}. Write down the corresponding set of quantum numbers for the third electron in the lowest energy state of the Li atom. Briefly explain the factors motivating the set of quantum numbers

Homework Equations


The Attempt at a Solution



Haven't done quantum numbers in a while.

The first shell is full so n=2. It is Lithium so it is still in the s orbital so l = 0
Firstly is this correct?

Now is where I get a little confused. Do the electrons have a preference when it comes to the m{s} numbers? Does it prefer to fill m{s} +1/2 before -1/2

My final answer for this question is (2,0,0,+1/2) is this correct?

Thank you for your time.
 
Last edited:
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n=2, L=m(l)=0 should be correct for the reasons you have outlined above.
If you are being asked for the corresponding Set(!) of quantum numbers I believe you want to include both the spin-up and spin-down states in your answer.
 

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