What is the charge for the ion?
N contains 7 electrons by itself. 2 electrons are core electrons, 5 electrons are valence electrons (2+5). Each electron can be removed one at a moment. An N+1 has 6 electrons (2+4), N2+ 5 (2+3) and N3+ 4 (2+3) respectively. You can also add electrons to the nitrogen one at time. N- now has 8 electrons. To make it negative (2+6), you can add one electron to it. N2- would have nine electrons (2+7), while a n3+ has 10 electrons (2+8). This last set of numbers (2+8) indicates that the n=1 shell has been filled (1s2), and the n=2shell is also filled (2s22p6). This is the nobel gas configuration. Nitride is a -3 ion nitrogen.