Textbook 1E7

[Ryan M]

Why is only D expected for ground? I thought that B (Nitrogen) would also be expected since it has 7 electrons and it fills in the orbitals 1 at a time. Any help would be appreciated!

[Devika Nair 2D]

Hi! For N to be in its ground state, all of the unpaired electrons in the p orbital would have to have the same direction spin (parallel). It doesn't matter if they are all spin up or spin down, but they must all be the same. The electron in the second orbital has a downward spin when the other two have upwards spin, so it is not in the ground state.

[Jamie Lin 1K]

In order for nitrogen to be in the ground state, the three electrons in their respective 2p orbitals would all have the same spin, which is not the case here.

[Sophia Olender 2J]

The nitrogen configuration has the second electron with an opposite spin (arrow pointing down). According to Hund's rule, all of the electrons in singly occupied orbitals have the same spin in order to maximize total spin. Electrons all spinning the same way have lower energy.

[Rebekah Han 2K]

If we're following Hund's Rule, all the electrons, if unpaired, must be the same spin. Since the three electrons in the three orbitals of 2p are not the same spin, (ie two arrows are facing up and one arrow is facing down), it is not in the ground state. Granted, all the unpaired electrons could be spin down and it would still be in the ground state.

[Allison Peng 1D]

Yeah! Also i believe the spin states are also just convention, and convention states that we start with upspin, so mainly just follow those guidelines (as to why it's not all downspin) - but as long as they're all in the same state (parallel) it basically means the same thing.