How can I sum up the definition of an elements oxidation number?
A great way to start to sum up this definition is to memorize the oxidation rules: 1. Elemental state= 0. 2. Monatomic ion equals the charge of the ion. (ex Na+ is +1 N3- is -3.) 3. Group IA +1 all compounds. 4. Group 2A +2 all compounds 5. Group 3A +3 all compounds few exceptions. 6. Hydrogen is +1 non-metal and metals -1. 7. Oxygen -1 in peroxides and -2 all other compounds. 8. Halogens group 7A elements. Fluorine -1 all compounds. Other Halogens in a compound is -1, except when that element is combined with O or a lighter halogen. 9. The sum of the O.N. of all of the atoms in a neutral compound is 0. An element in a compound will always equal 0. However, you can use the rules above to assign oxidation numbers to elements in a compound. For example H2O oxygen according to the rules is always -2 unless its a peroxide so we know oxygen is -2 and we need the oxidation’s numbers to equal 0 for the entire compound… so we assign +1 to hydrogen because 2 multiplied by +1 = +2 and +2 -2= 0
