The oxidation numbers (also known as oxidation state) is a number given to each atom or ion in a compound to keep track of how many electrons they have
In a single ion or molecular ion, the oxidation number tells us how many electrons have been lost or gained
Positive oxidation number = loss of electrons
Negative oxidation number = gain of electrons
Oxidation number rules
The oxidation number (ox.no.) refers to a single atom in a compound