In the compound NH4+ ammonium ion , the oxidation state of nitrogen is -3. Here's the explanation: Hydrogen has an oxidation state of +1. Since there are four hydrogen atoms, the total positive charge contributed by hydrogen is +4. For the compound to have a net charge of +1, the nitrogen atom must have an oxidation state of -3, as -3 from nitrogen + 4 from hydrogen = +1 overall charge of the compound .