Oxidation Numbers: Understanding Chemical States

by Yuvi K - December 16, 2023

Understanding Oxidation Numbers

Oxidation numbers are a way for chemists to keep track of how many electrons an atom has lost or gained in a reaction. They provide a way of determining the charge of an atom in a compound or molecule, and can help in understanding the reactivity of the compound or molecule. In this article, we will look at the basics of oxidation numbers, including what they are, how to determine them, and how they are used in reactions.

What Are Oxidation Numbers?

An oxidation number (or oxidation state) is the charge of an atom or molecule in a reaction. It is equal to the number of electrons that have been lost or gained in the reaction. For example, an atom with an oxidation number of +2 has gained two electrons in a reaction, while an atom with an oxidation number of -3 has lost three electrons. Oxidation numbers are usually written as superscripts next to the element’s symbol.

How to Determine Oxidation Numbers

A useful way to determine oxidation numbers ( रसायनिक सम्पत्तियों को पहचानने के लिए ) is to use the following rules:

• Each element in its free ( unbound ) state ( अपरिभ्रष्ट ) has an oxidation number of zero.
• The oxidation number of a monatomic ( एकमात्रिक ) ion is equal to the charge of the ion.
• The sum of the oxidation numbers of all the atoms in a neutral compound ( न्यूट्रल कंपाउंड ) is zero.
• The sum of the oxidation numbers of all the atoms in a polyatomic ion ( पॉलीआटोमिक आयन ) is equal to the charge of the ion.
• In a molecular compound ( मॉल्यूलर कंपाउंड ), the more electronegative element ( विषयोप्रभवी तत्व ) is usually assigned an oxidation number of negative value.

Examples of Oxidation Number Determination

Example 1

Let’s look at the oxidation numbers of K and O in potassium oxide, K2O. The oxidation numbers of the atoms in potassium oxide are as follows:

Note that the sum of the oxidation numbers of the atoms in this compound is zero, as required for a neutral compound.

Example 2

Now, let’s look at the oxidation numbers of H and Cl in hydrochloric acid, HCl. The oxidation numbers of the atoms in hydrochloric acid are as follows:

Note that the sum of the oxidation numbers of the atoms in this compound is also zero, as required for a neutral compound.

Using Oxidation Numbers for Reactions

Oxidation numbers can be used to determine the type of reaction that is occurring. For example, if an atom has an oxidation number of zero before a reaction, but has a negative oxidation number after, then it has been oxidized. Similarly, if an atom has an oxidation number of zero before a reaction, but has a positive oxidation number after, then it has been reduced.

Conclusion

In conclusion, oxidation numbers provide a way to keep track of the electrons lost or gained in a reaction. In addition, they can be used to determine the type of reaction that is occurring. It is important to remember the rules for determining oxidation numbers, as this will help to ensure accurate results. With a firm understanding of oxidation numbers, you will be able to understand and analyze reactions like a pro!