Oxidation State Definition

                Oxidation number of the element is defined as the residual charge which its atom has or appears to have when all other atoms from the molecules are removed as ion. In ions the oxidation state is the ionic charge. In covalent compounds the oxidation state corresponds to the formal charge. In elements the oxidation state is zero.
Example:
In NaCl the oxidation states are Na (+1) and Cl (-1).
In CCl_{4 the oxidation states are C (+4) and Cl (-1).
Note :
The oxidation is the difference between the number of electrons associated with an atom in a compound as compared with the number of electrons in an atom of the elements.}