Thermite is one of the most dangerous chemical reactions humans have conceived of. Created when aluminium powder is mixed with a metal oxide (typically iron oxide) and ignited, the two metals erupt in a violent burst of light and intense heat.
This volatile reaction is the result of oxygen atoms being exchanged between a molecule of iron oxide and aluminium atoms, which means the molecular bonds that grip oxygen to its metal companion are broken and reformed. In doing so, energy is released in the form of heat, in what’s known as an exothermic reaction. When reactants such as iron oxide and aluminium have a higher internal energy, known as enthalpy, than the products made by the reaction, the excess energy is released as heat or light.