Question

Nitrogen +5 oxidation state in nitric acid

Answer 1

Generally, the simpliest intuition for this is to imagine that nitrogen looses one electron, becoming isoelectronic to carbon. After forming four bonds with, say, fluorine, we gain NF4+NFX4X+ cation where nitrogen is connected to four more electronegative atoms and have positive charge to begin with, thus +5 oxidation state. In some compounds, say, nitric acid, the electron is not moving too far, instead migrating to nearest oxygen, so nitrate anion is actually isoelectronic to carbonate dianion.