Question

what are the rules in determining oxidation numbers of an element​

Answer 1

The oxidation number of a free element is always 0. The atoms in He and N2, for example, have oxidation numbers of 0. The oxidation number of a monatomic ion equals the charge of the ion. For example, the oxidation number of Na+ is +1; the oxidation number of N3- is -3.

Answer 2

Rules in determining oxidation numbers of an element are as follows :

• In elements the uncombined state, each atom bears an oxidation number of zero.
• The oxidation number of O in most compounds is -2 exception number is equal to the charge on the ion.
• For ions composed of only one atom, the oxidation number is equal to the charge on the ion.
• Fluorine always represented by oxidation state -1.
• The oxidation number of H is +1 except when it is bonded to metal in binary compounds it takes -1.
• The algebraic sum of the oxidation number of all the atoms in a compound must be zero.

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