Anion names homoatomic anions, 336

The increasing complexity of these homoatomic anions is well reflected by the following systematic names ... 

Secondly, a triply bonded dinitrogen molecule, in which each nitrogen has an oxidation of zero, bonds to the atomic nitrogen anion to give rise to one of the canonical structures of the azide anion, namely, one terminal nitrogen has one lone pair and three homoatomic bonds, and so has an oxidation number of zero. The central atom has four homoatomic bonds, but one of which is polarised away from it, i.e. the dative bond, and so it has an oxidation number of+1. The other terminal nitrogen started with one extra electron and now also has a homoatomic bond, which is polarised towards it, and so now has an oxidation number of-2. This nitrogen atom has three lone pairs. 

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