In the compound HNO3 , what is the correct oxidation number of each of its clements? The rules for assigning Oxidation States are given as below) 1) The oxidation numbers of the atoms in a neutral molecule must add up to zero. 2) Group I -- +1; Group 11 -- +2; Group III - +3 3) Fluorine--1 (always) Halogens--1 (except in compounds with O and other halogens) 4) Hydrogen - +1 (except in metal hydrides, e.g. LiH, Rule 2 and H has -1) 5) Oxygen --2 (except in compounds with F, Rule 3) and compounds with O-O bonds (Rules 2 & 4)