Iron reacts with oxygen when it burns. This is a classic example of a combustion reaction.

The chemical reaction looks like this:

3Fe + 2O₂ → Fe₃O₄

This means:

* 3 atoms of iron (Fe) react with 2 molecules of oxygen (O₂)

* to form 1 molecule of iron oxide (Fe₃O₄), commonly known as rust.

The heat from the burning iron provides the energy needed to start the reaction, and the reaction releases more heat and light, creating the familiar glow of burning iron.