Hund's Rule Spin: +1 vs -1 | Wiki Explanation

[atwong713]

http://en.wikipedia.org/wiki/Image:Si_Hund.png

can someone help clarify something for me
in this diagram why is it that the arrow is placed in +1 first and in my textbook it is placed in -1 first?

 

[Borek]

Does it really matter? As long as there is no external magnetic field these orbitals are degenerated, so they can be occupied in any order.

 

[Blueshift5]

I can provide some clarification on this issue. Hund's Rule states that when filling orbitals of equal energy, electrons will occupy each orbital with parallel spins before pairing up. This means that in the diagram, the first electron will be placed in the +1 spin state, and the second electron will also be placed in the +1 spin state. Only after all orbitals have one electron in the +1 spin state will the second electron be placed in the -1 spin state. This is because electrons prefer to have the same spin, so it is energetically favorable for them to occupy the same spin state before pairing up. Therefore, the diagram is correct in showing the +1 spin state being filled first. Your textbook may have placed the -1 spin state first for simplicity or to emphasize the concept of spin, but the ultimate result will be the same. I hope this helps clarify any confusion.