aluminium is above iron in the reactivity series. however its reactions with oxygen and water appear to show that it is less reactive than iron. explain.
Even though aluminium is more reactive than iron (aluminium is above iron in the reactivity series) it does not corrode much as iron because the aluminium reacts with oxygen in the air to form a layer of oxide, which protects the aluminium from further oxidation. On the other hand the oxides of Iron (rust) tend to fall away, exposing the unreacted iron to further oxidation.
Hence aluminium is less reactive to oxygen and water than iron.