Guidelines - Oxidation States of Nonmetals
1. When two, nonmetals react with each other, the more electronegative element is assigned the negative oxidation state. 
a. Fluorine, the most electronegative element, is always assigned an oxidation state of "-1" when combined with any other element. 
b. Hydrogen, whenever it is combined in a molecule, is assigned an oxidation state of "+1". 
c. When hydrogen combines with metals in forming compounds called, metal hydrides, it is assigned an oxidation state of (-1) 
2. Oxygen, in most compounds, is usually assigned an oxidation state of "-2". 
a. However, when it is found in peroxides (" O - O bonds ") it is assigned a value of "-1"; or when combined with fluorine, it is assigned a value of "+1". 
3. The sum of the oxidation states of every element in a substance or species (it may be an ion or a molecule) must always equal the electrical charge indicated for that substance or species. 
a. any monatomic ion has an oxidation state equal to its charge 
b. the sum of the oxidation states of all atoms in a compound must equal zero. 
c. the sum of the oxidation states of all atoms in a polyatomic ion must equal the charge of the ion.