Jacobus Henricus van't Hoff. (Source: University of Pittsburgh)

In 1872 Jacobus Henricus van't Hoff (1852–1911), a Dutch graduate student, came to Bonn to study for a year. From August Kekulé von Stradonitz, van't Hoff learned of a possible tetrahedral arrangement of the valence bonds of carbon, proposed by the Russian chemist Alexander Mikhailovich Butlerov in 1862. In 1873, after van't Hoff had moved to Paris to work with Charles Adolphe Wurtz, he realized that the phenomenon of optical activity possessed by some organic molecules—their ability to rotate plane-polarized light—could be explained by the two possible arrangements of four different substituents in the space around a carbon atom. This theory provided substantial indication that the molecular structures the chemists of the time were discussing had a physical reality in three-dimensional space and were not just aids to conceptualizing molecules. (Another graduate student working in Wurtz's laboratory, Joseph Achille Le Bel, arrived at the same explanation of optical activity independently.)

Van't Hoff returned to the Netherlands to complete his doctoral degree. He was soon appointed lecturer in theoretical and physical chemistry at the University of Amsterdam, where he stayed for 20 years. There he conducted the studies of reaction rates, chemical equilibrium, chemical affinity, and osmotic pressures that helped found the discipline of physical chemistry. In 1896 he moved to the University of Berlin, and in 1901 he became the first Nobel laureate in chemistry for his work in physical chemistry.

Further Reading

• American Chemical Society
• Chemical Heritage Foundation
• Society of Chemical Industry
• The Chemists' Club