This Day In History: 1823-08-03

German chemist Johann Dobereiner discovered the role of platinum (Pt) as a catalyst. He realised that a platinum (Pt) sponge could cause the ignition of hydrogen (H) at room temperature by lowering the activation energy. This effect was the precursor to the theory of catalysis, and in 1835 the term “catalyst” was coined by Swedish chemist Jacob Berzelius.  Nearly a decade earlier, in 1829, Döbereiner reported trends in certain properties of selected groups of elements. For example, the average atomic mass of lithium and potassium was close to the atomic mass of sodium. A similar pattern was found with calcium, strontium, barium, sulfur, selenium, tellurium, bromine and iodine. Moreover, the densities for some of these triads followed a similar pattern. These sets of elements became known as “Döbereiner’s triads“