For example, if you add chlorine to a sodium bromide solution, chlorine would displace bromine since it's more reactive. The halogen atoms then gain electrons to form halide ions, which are reduced. In a displacement reaction, the more reactive halogen atoms oxidise the less reactive halide ions, causing the halide ions to lose electrons and form halogen atoms.
This occurs when a more reactive halogen replaces a less reactive halide in a compound. Let's take a closer look at one type of reaction that involves halogens - a displacement reaction. In fact, fluorine is one of the most potent oxidising agents out there! To recap redox reactions, check out Redox. In general, the oxidising power of the halogens decreases as you go down the group. This means that an oxidising agent takes electrons from another species and gains them itself.
