19.1 How to Assign Oxidation Numbers
Oxidation – loss of electrons
Reduction – gain of electrons
Rules for Assigning Oxidation Numbers
1. Elements in their elemental form are in the zero oxidation state.
2. Group 1 metals are +1 and Group 2 metals are +2.
3. Hydrogen is +1 except when bonded to a metal only (when it’s –1).
4. Transition elements must be determined from anion’s charge
(except Al = +3, Zn = +2, Cd = +2, Ag = +1)
5. The most electronegative elements get their typical oxidation state.
6. The last element not assigned balances the charge of the compound/ion.
Determine the oxidation numbers of all elements in the following: