# What is the difference between water and hydrogen peroxide?

On the one hand you have water, ${H}_{2} O$, and on the other hand you have hydrogen peroxide, $H - O - O - H$, with a peroxo bond. Because this $O - O$ is fairly weak, hydrogen peroxide is a reactive species and readily forms hydroperoxyl radicals, $H O \cdot$, that go on to react with other substituents.