How do halogens behave as oxidising agents?

Halogens behave as oxidising agents by accepting electrons during a chemical reaction, thereby causing the oxidation of other substances.

Halogens, which include elements like fluorine, chlorine, bromine, iodine, and astatine, are found in Group 7 of the Periodic Table. They are known for their high electronegativities, which means they have a strong tendency to attract and accept electrons. This characteristic makes them excellent oxidising agents.

In a chemical reaction, an oxidising agent is a substance that has the ability to oxidise other substances. This means it causes other substances to lose electrons. When a halogen acts as an oxidising agent, it gains electrons from another substance, causing that substance to be oxidised. This process is known as a redox (reduction-oxidation) reaction. In this type of reaction, the halogen is reduced (it gains electrons) and the other substance is oxidised (it loses electrons).

For example, consider the reaction between chlorine (a halogen) and sodium bromide. In this reaction, chlorine acts as an oxidising agent and oxidises the bromide ions to bromine. At the same time, the chlorine is reduced to chloride ions. This is represented by the following equation: Cl2 + 2NaBr -> 2NaCl + Br2. Here, the chlorine has accepted electrons from the bromide ions, causing the bromide to be oxidised to bromine.

The ability of halogens to act as oxidising agents decreases down the group. This is because the ability to attract and accept electrons decreases as you go down the group. Fluorine, at the top of the group, is the most powerful oxidising agent, while astatine, at the bottom, is the least powerful.

In summary, halogens behave as oxidising agents due to their high electronegativities and their ability to accept electrons during chemical reactions, causing the oxidation of other substances.