I have worked out the total spin for the elements up to Neon however I hit a snag with Nitrogen and Fluorine. The shell sequence of nitrogen 7N7 is 1s2, 2s2, 2p3 for both the proton and neutron and the total angular spin is 1 Likewise, Fluorine 9F10 is 1s2, 2s2, 2p5 for the proton and 1s2, 2s2, 2p6 for the neutron and the total angular spin is ½ In the nitrogen isotope it would appear that the 3 protons and neutrons are not paired and occupy separate states in the 2p shell. Thus the total orbital angular momentum would be 3 and the total spin would be 3/2 for the protons and additional for the neutrons suggesting the total angular momentum of 9 which is wrong. So do 2 of the protons in different states in the 2p shell pair up their orbital and spin angular momentum? Likewise do 2 of the neutrons in the 2p shell pair up their orbital and spin angular momentum? If so, this would leave yield an orbital momentum of 1 for the proton and 1 for the neutron; likewise, the spin of the two separate nucleons sum up to 1. This would then yield a total angular momentum of 2 + 1 = 3 with is also wrong. The only way I can see to achieve a total angular momentum of 1 is if the spin of the proton and neutron were both negative, which I considered wrong because unpaired particle spin were always positive. So can an unpaired particle have a negative spin? With respect to 9F10 there are 2 sets of paired protons plus 1 separate in the 2p shell and all neutrons are paired. This would produce an orbital angular momentum of 1 and a spin of ½ for a total of 3/2; however JANICE indicates this isotope has only ½ spin suggesting the proton spin was -1/2. Can anyone shed any light on the total spin of these two isotopes?