Question

What are the rules to determine oxidation number?​

Answer 1

Rules for determining oxidation number are follows-

1. If element is present in free state then the oxidation number is assigned at 0.

Examples- Na, Zn, Mg, H etc.

2. Oxidation number of the following group elements are given according to their group number.

Examples-

Group no.of IA = 1

Group no.of IIA = 2

Group no.of IIIA = 3.

3. For the elements present in IVA to VIIA oxidation number is Devon according to the range i.e. n - 8 to "n" is the group number.

Examples-

Group no.of IVA = -4 to +4

Group no.of VA = -3 to +5

Group no.of VIA = -2 to +6

Group no.of VIIA = +1 to +7

4. If element is bounded with same element then the oxidation number of the element will be zero.

Examples- Cl2, O2, N2, Br2 etc.

5. Oxidation number of the constituent element of an alloy is taken as zero.

Example- Na - Hg (Sodium Amalgam)

Oxidation Number of Na = 0

Oxidation Number of Hg = 0.

Answer 2

The convention is that the cation is written first in a formula, followed by the anion. ...

The oxidation number of a free element is always 0. ...

The oxidation number of a monatomic ion equals the charge of the ion. ...

The usual oxidation number of hydrogen is +1. ...

The oxidation number of oxygen in compounds is usually -2.