How to Calculate Oxidation Numbers

To understand and predict the behaviour of chemical compounds, it is important to be able to calculate oxidation numbers. This process assigns a number to each atom in a molecule, reflecting the degree of oxidation of that atom. In this article, we will walk you through how to calculate oxidation numbers step-by-step. We will also provide some examples so that you can practice what you have learned. Are you ready to get started?

Calculation of Oxidation Number

To calculate the oxidation number of an element, you will need to know the following:

• The charge of the element in its elemental form
• The charge of the element in its compounds
• The number of valence electrons in its elemental form

With this information, you can calculate the oxidation number of an element using the following steps:

First, determine the charge of the element in its elemental form. This can be found on the periodic table. The charges of elements in their elemental form are typically either zero or negative.

Next, determine the charge of the element in its compounds. This can be found in the compound’s formula. The charges of elements in their compounds are typically either positive or negative.

Finally, determine the number of valence electrons in their elemental form. This can be found on the periodic table. The number of valence electrons is typically equal to the atomic number of the element.

With this information, you can now calculate the oxidation number of an element using the following equation:

Oxidation Number = (Elemental Charge) + (Compound Charge) – (Valence Electrons)

For example, let’s say we want to calculate the oxidation number of oxygen in the water. We know that the elemental charge of oxygen is zero, the compound charge of oxygen in water is -II, and the valence electrons of oxygen are eight. Therefore, we can calculate the oxidation number of oxygen in the water as follows:

Oxidation Number of Oxygen in Water = (0) + (-II) – (VIII)

Oxidation Number of Oxygen in Water = -II

As you can see, the oxidation number of oxygen in water is -II. This means that oxygen has been oxidized from its elemental form (in which it has a charge of zero) to its compound form (in which it has a charge of -II).

You can use this same method to calculate the oxidation number of any element in any compound. Just remember to use the correct charges and valence electrons for the element you are calculating.

Calculation of Oxidation Number of atoms, Occurring Only Once in a Molecule

When an atom occurs only once in a molecule, its oxidation number is equal to the charge on the molecule.

For Example, The oxidation number of Manganese in permanganate ion MnO4–:

Here, manganese is the only atom in the molecule, so its oxidation number must be equal to the charge on the molecule.

The charge on permanganate ion is -I so, the oxidation number of manganese = -I

Calculation of Oxidation Number of atoms Occurring More Than Once in a Molecule

When an atom occurs more than once in a molecule, its oxidation number is equal to the charge on the atom.

For Example, The oxidation number of chlorine in HClO:

Here, chlorine is present three times, so its oxidation number must be equal to the charge on each atom.

The charge on HClO is -I so, the oxidation number of chlorine = -I/III = -I

Calculation of Oxidation Number of atoms in Polyatomic Ions

When an atom is part of a polyatomic ion, its oxidation number is equal to the charge on the ion.

For Example, The oxidation number of sulphur in HSO:

Here, sulphur is present in the polyatomic ion SO and its oxidation number must be equal to the charge on the ion.

The charge on SO is -II so, the oxidation number of sulphur = -II/I = -II.

Conclusion

To understand oxidation numbers, you must first know what they are used for. Oxidation numbers can be used to determine the number of electrons lost or gained in a chemical reaction. This is important because it helps chemists figure out which elements are oxidized and reduced in a particular reaction. By understanding how to calculate oxidation numbers, you will be able to better follow and predict chemical reactions. We hope this tutorial has helped clear up any confusion about oxidation numbers and their calculation. Are there any specific questions that remain unanswered? Let us know in the comments below, and we would be happy to help!