Oxidation Rules - Covalent Compounds

• An uncombined element has an oxidation number of zero.
• The sum of oxidation numbers in a compound is zero. In a complex ion, the sum of the oxidation numbers = charge on the ion.
• Group one metals have an oxidation number of +1 and group two metals have a oxidation number of +2 in compounds.
• Oxygen always has an oxidation number of -2 in compounds (except with fluorine and in peroxides and superoxides).
• The oxidation number of hydrogen is always +1 in compounds, except in metal hydrides.
• When you have ions or compounds with atoms of more than one element, the most electronegative element is given the negative oxidation number.