What makes a substance a good oxidising agent?

A good oxidising agent is a substance that readily accepts electrons, having a high affinity for them.

An oxidising agent, also known as an oxidant or oxidiser, plays a crucial role in the process of oxidation-reduction (redox) reactions. In these reactions, the oxidising agent gains electrons, thereby getting reduced itself. The ability of a substance to act as a good oxidising agent is determined by its electron affinity, which is the amount of energy released when an electron is added to a neutral atom or molecule to form a negative ion.

The more readily a substance accepts electrons, the better an oxidising agent it is. This is because the process of oxidation involves the loss of electrons from one substance, and these electrons must be accepted by another substance - the oxidising agent. Therefore, substances with a high electron affinity, such as halogens and oxygen, are often good oxidising agents.

For example, in the reaction between hydrogen and fluorine to form hydrofluoric acid, fluorine acts as an oxidising agent because it accepts an electron from hydrogen. Fluorine has a high electron affinity, which makes it a good oxidising agent.

Moreover, the strength of an oxidising agent can also be influenced by its position in the electrochemical series, which ranks elements based on their ability to donate or accept electrons. Elements at the top of the series, such as fluorine, are strong oxidising agents because they have a high tendency to gain electrons.

In summary, a good oxidising agent is characterised by its high electron affinity and its position in the electrochemical series. These factors determine its ability to readily accept electrons in a redox reaction, thereby enabling the oxidation of other substances.