Oxidation is loss of electrons and Reduction is gain of electrons
Reactions that involve the transfer of one or more electrons from one reactant to another are called oxidation – reduction reactions.
Simple meaning of oxidation reaction would be an addition of oxygen to a substance. Reduction reaction would mean removal of oxygen form a substance.
Oxidation is the process whereby a reactant loses one or more electrons results in increase in its oxidation state. Reduction is the opposite process whereby a reactant gains one or more electrons with decrease in oxidation state. Oxidation and reduction are complementary and simultaneous processes. They always occur together. The electrons lost by one chemical in an oxidation reaction don't simply disappear; they are gained by another chemical in a reduction reaction.
- Sodium get inert gas configuration of Neon (1s22s22p6) by losing one electron.
- Chlorine get inert gas configuration of Argon (1s22s22p63s23p6) by gaining one electron.
An oxidation – reduction reaction occurs when elemental sodium and chlorine react exothermically to form sodium chloride, as shown in the adjacent figure. The equation for this reaction is
To see how electrons are transferred in this reaction, we can look at each reactant individually. Each electrically neutral sodium atom changes to a positively charged ion – each atom loses an electron and is therefore oxidized:
Each electrically neutral chlorine molecule changes to two negatively charged ions – each atom gains an electron and is therefore reduced:
The net result is that the two electrons lost by the sodium atoms are transferred to the chlorine atoms. Therefore, the two equations shown above actually represent one process, called a half reaction. In other words, an electron won't be lost from a sodium atom without there being a chlorine atom available to pick up that electron. Both half reactions are required to represent the whole oxidation – reduction process.
Because the sodium causes reduction of chlorine, the sodium is acting as a reducing agent, which is any reactant that causes another reactant to be reduced. Note that in behaving as a reducing agent, the sodium is oxidized – it loses electrons.
Conversely, the chlorine causes oxidation of the sodium and so it is acting as an oxidizing agent. Because it gains electrons as it causes another reactant to be oxidized, an oxidizing agent is reduced. Just remember that loss of electrons is oxidation and gain of electrons is reduction.
Burning of coal is an oxidation process
Burning of coal and magnesium wire are oxidation processes.
A common example of reduction is the burning of wood. Wood is mainly cellulose, a substance made up of carbon and hydrogen (C6H10O5)n. As wood burns, its carbon – hydrogen bonds break and the carbon and hydrogen atoms form new bonds with oxygen molecules in the air to create carbon dioxide and water. The formation of these products involves the transfer of electrons from one atom to another and so is by definition an oxidation – reduction reaction.