Roald HoffmannBorn 18 Jul 1937. Polish-born American chemist, corecipient, with Fukui Kenichi of Japan, of the Nobel Prize for Chemistry in 1981 for their independent investigations of the mechanisms of chemical reactions. His work aims at theoretically anticipating the course of chemical reactions. It is based on quantum mechanics (the theory whose starting point is that the smallest building blocks of matter may be regarded both as particles and as waves), which attempts to explain how atoms behave. Orbital interaction and symmetry relations between molecules or parts of molecules are fundamental to this theory of conservation of orbital symmetry in chemical reactions.