aluminium and bromine

The reaction of aluminium with bromine. Who would have thought that aluminium was so reactive anyway? We wrap our food in it, don't we?

Being protected by an air tight, water tight layer of aluminium oxide on its surface, it is perfectly safe to use as cooking foil. However, bromine is a bit frisky, and once it strips off this thin oxide layer to reveal the reactive aluminium metal beneath, the resulting reaction is highly exothermic.