How to find oxidation number & oxidation state - important concepts in chemistry. We go over the rules and make them very easy to understand. Oxidation States Oxidation state (or oxidation numbers) do not refer to real charges on the atoms, except in the case of actual ionic substances. Oxidation numbers can be determined using the following rules: The oxidation number for an element in its elemental form is 0 (holds true for isolated atoms and elemental substances which bond identical atoms: e.g. Cl 2, etc) The oxidation number of a monoatomic ion is the same as its charge (e.g. oxidation number of Na + = +1, and that of S 2- is ... Oxidation Number of Periodic Table Elements Oxidation number or state of periodic table elements in a chemical compound or molecule is the formal charge (positive or negative) which assigned to the element if all the bonds in the compounds are ionic. In chemistry, the oxidation number or state is defined as the total number of electrons lost or gained by atoms or ions to form a chemical bond. Some general rules used in learning chemistry to find out or calculate the oxidation number or state ... This page explains what oxidation states (oxidation numbers) are and how to calculate and use them.