Oxidation means loss of electron and Reduction means a gain of an electron.

Modern Concept of Oxidation and Reduction Reaction

Oxidation and reduction reactions are chemical reactions that involve the transfer of electrons between two species. The modern concept of oxidation and reduction is based on electron transfer, which occurs when one species loses electrons (oxidation) and another species gains electrons (reduction).

Oxidation: It is defined as the loss of electrons or increase in oxidation state. For example, when iron reacts with oxygen to form rust, it undergoes oxidation.

Reduction: It is defined as the gain of electrons or decrease in oxidation state. For example, when copper ions gain electrons to form copper metal, it undergoes reduction.

Oxidation Number

Oxidation number is the number assigned to an atom in a molecule or ion that reflects its ability to gain or lose electrons. It is a positive or negative number that indicates the degree of oxidation or reduction of an atom in a compound.

Rules to find Oxidation Number

1. The oxidation number of an atom in an element is zero.
2. The sum of oxidation numbers of all atoms in a compound is zero.
3. The sum of oxidation numbers of all atoms in a polyatomic ion is equal to the charge of the ion.
4. The oxidation number of hydrogen is +1 in compounds containing elements with higher electronegativity, and -1 in compounds containing elements with lower electronegativity.
5. The oxidation number of oxygen is -2 in most compounds, except in peroxides and superoxides where it is -1 and -1/2 respectively.
6. The oxidation number of fluorine is -1 in all compounds.
7. The oxidation number of alkali metals is +1 and alkaline earth metals are +2 in all compounds.
8. The oxidation number of non-metals such as carbon, nitrogen, sulfur, and phosphorus can vary depending on the compound.

Conclusion

In modern concept, oxidation and reduction are based on electron transfer and oxidation number is a positive or negative number that indicates the degree of oxidation or reduction of an atom in a compound. To find the oxidation number, we follow certain rules such as the oxidation number of hydrogen is +1 or -1 depending on the compound, the oxidation number of oxygen is -2 in most compounds, and the sum of oxidation numbers of all atoms in a compound is zero.