Air is mostly nitrogen. Alone it is innocuous. But only because in air nitrogen has already formed molecules of two nitrogen atom. I would guess, it would not

Air is mostly nitrogen. Alone it is innocuous. But only because in air nitrogen has already formed molecules of two nitrogen atom. I would guess, it would not be a pleasant experience to be exposed to atomic nitrogen if this were possible. This contrast between nitrogen gas and other substances containing nitrogen atoms really makes no sense, there is just no relationship between the properties of elements and the properties of compound containing those elements, at the very least not in general. The fact that it becomes dangerous when processed with other elements is the whole point of the sentence. TNT is not directly made from nitrogen but from toluene and nitric acid which are both not innocuous and the later is unlike nitrogen gas and TNT. But it boils down to the point from before, in chemistry it makes not really sense to relate the properties of what goes into a reaction and what comes out. It might cause just minor changes in the properties but it might also change the character completely. And you can also arrive at the same compound via different routes involving different precursors with different properties. Arbitrarily picking some and comparing them to the product is not meaningful most of the time.