• Méthode de Nomenclature Chimique, by Louis Bernard Guyton de Morveau, Antoine Laurent Lavoisier, Claude Louis Berthollet, and Antoine François de Fourcroy, is published in Paris. Created from Greek and Latin roots, the nomenclature system represents what Lavoisier’s followers understand about the composition of hundreds of substances.



Early chemical symbols and those created by Jean Henri Hassenfratz and Pierre Auguste Adet to complement the Methode de Nomenclature Chimiqe (1787). Courtesy of the Edgar Fahs Smith Memorial Collection, Department of Special Collections, University of Pennsylvania Library.


  • Jöns Jakob Berzelius proposes a system of chemical symbols in which elements are represented by the first letters of their names. Compounds are represented by these letters with superscripts indicating combining weights, which in turn suggest the number of atoms combining.


  • The Pharmacopoeia of the United States is published, establishing standard English and Latin names for drugs.


  • In a published outline of a chemistry course, Stanislao Cannizzaro clarifies the calculation of atomic weights, then a highly contentious subject, using, in part, the long-neglected hypothesis put forward by Amedeo Avagadro in 1811.
  • Friedrich August Kekule and Archibald Scott Couper recognize that carbon atoms have the ability to link to one another in chains.
  • Archibald Scott Couper uses straight lines to indicate valence bonds in organic compounds, as is still the practice in most modern structural diagrams.


  • Congress is held at Karlsruhe Technische Hochschule to discuss the feasibility of establishing a systematic and rational nomenclature for chemistry. The congress does not reach any conclusive results, but several key participants return home with Stanislao Cannizzaro’s outline (1858), which ultimately convinces them of the validity of his scheme for calculating atomic weights.


  • Friedrich Kekule, as well as others, including Josef Loschmidt, identifies the ring structure of benzene.


  • Dmitri Ivanovich Mendeleev publishes a periodic table of the elements organized by atomic weight, similar chemical and physical characteristics, and valence.


  • Julius Lothar Meyer publishes a periodic table similar to Dmitri Ivanovich Mendeleev’s that he has been developing since 1864.


  • Jacobus Henricus van’t Hoff and Joseph Achille LeBel’s recognition that there are two ways of arranging four unlike substituents tetrahedrally around a carbon atom marks the beginning of three-dimensional structural organic chemistry and the associated problem of representing these structures graphically and, much later, in a machine-readable code.


Three-dimensional paper models used by Jacobus Henricus van’t Hoff in communicating his stereo-chemical ideas.  Courtesy O. Bertrand Ramsay.


  • London’s Chemical Society publishes Nomenclature and Notation, guidelines for establishing systematic and uniform practices.


  • ACS establishes the Committee on Nomenclature and Notation.


  • Geneva conference establishes principles that set the stage for an evolving chemical nomenclature. These principles are developed more fully by various forerunners of the International Union of Pure and Applied Chemistry (IUPAC), which was founded in 1919.


  • Alfred Werner introduces a systematic nomenclature for coordination compounds based on the groups surrounding a central metal atom.


  • Editor Evan J. Crane publishes first CA decennial index (1907-1916), which includes a new means of naming and indexing compounds developed by Austin M. Patterson and Carleton C. Curran.


  • IUPAC establishes commissions on chemical nomenclature to formulate rules for naming chemical compounds systematically.


  • Conrad Weygand, a German chemist, proposes a method for classifying chemical reactions based on the breaking and forming of bonds during a reaction.


  • G. Malcolm Dyson presents a paper before London’s Royal Institute of Chemistry on his notation system, which seeks to represent chemical structures uniquely and unambiguously in a linear sequence of letters and numbers. International Union for Pure Applied Chemistry provisionally recommends the Dyson system.


  • Welch Medical Library Indexing Project at Johns Hopkins University begins. Sponsored by the Army Medical Library (now the National Library of Medicine), it is one of the first efforts to study medical and chemical nomenclature and indexing and to apply machine technologies to this information.


  • George Willard Wheland, professor at the University of Chicago, develops basic concept of the connection table to represent chemical structures.
  • William J. Wiswesser introduces Wiswesser Line Notation.


  • National Research Council issues a call for the comparative study of the best notation systems for structural formulas.


  • Robert Cahn, Christopher Ingold, and Vladimir Prelog present a nomenclature system for the unambiguous specification of stereoisomers.


  • IUPAC approves rules for chemical nomenclature that are subsequently issued in book form–the famous Red, Blue, and Green Books, dealing with inorganic, organic, and physical chemistry, respectively.


  • Beilsteins Handbuch adopts CIP (for Cahn, Ingold, and Prelog). CIP is now used nearly universally.


  • CAS introduces the hetero-atom-in-context system in its chemical formula index.


  • Elias J. Corey and W. Todd Wipke of Harvard University develop the OCSS-LHASA (Organic Chemical Synthesis Simulation Logic and Heuristics Applied to Synthetic Analysis) synthesis planning system. Beginning with a molecular structure input by light pen or mouse, the system suggests starting materials and reactions to produce the molecule.