Linus Carl Pauling (February 28, 1901–August 19, 1994) was an American chemist whose research connected quantum mechanics with the structures and properties of substances. He received the Nobel Prize in Chemistry in 1954 for his work on chemical bonding and the Nobel Peace Prize for 1962 for opposing the nuclear arms race. Both awards were unshared. His scientific work extended from crystal structures to proteins and the molecular basis of inherited disease. (nobelprize.org)
Early life and academic career
Pauling was born in Portland, Oregon. He entered Oregon Agricultural College, now Oregon State University, in 1917 and graduated in 1922 with a degree in chemical engineering. While teaching an introductory chemistry course there, he met Ava Helen Miller; they married in 1923 and had four children. Ava Helen subsequently participated in peace campaigning alongside him and independently. (lpi.oregonstate.edu)
At the California Institute of Technology (Caltech), Pauling studied crystal structures using X-ray crystallography under Roscoe Dickinson, completing his doctorate in 1925. A Guggenheim fellowship supported study in Europe in 1926–1927, where he encountered the developing quantum theory. He joined Caltech’s faculty in 1927 and became chairman of its Division of Chemistry and Chemical Engineering in 1937. His research combined structural measurements, theoretical calculations, and models of molecular arrangements. (nasonline.org)
Chemical bonding and crystal structure
Pauling helped make quantum theory a practical framework for chemistry. He developed valence bond theory, describing bonding through interactions between atomic electronic states. His treatment of orbital hybridization related combinations of atomic orbitals to the directional arrangement of bonds, providing explanations for molecular shapes. He also developed the use of resonance: several contributing electronic descriptions can represent a single molecular state rather than separate structures between which a molecule alternates. (nasonline.org)
His electronegativity scale expressed the relative tendency of an atom to attract electrons in a bond. Differences on this scale helped characterize bond polarity and partial ionic character. In crystal chemistry, he formulated rules relating ionic sizes, coordination, and electrostatic requirements to the stability of structures. These became known as Pauling’s rules. (nasonline.org)
Pauling brought these ideas together in The Nature of the Chemical Bond, first published in 1939. The book connected quantum descriptions with measured bond lengths, bond strengths, and molecular and crystal structures. His 1954 Chemistry Nobel recognized research into bonding and its application to explaining complex substances, rather than a single discovery. (lpi.oregonstate.edu)
Proteins and molecular disease
Pauling extended structural chemistry into molecular biology. In 1951, he, Robert B. Corey, and Herman R. Branson published a model of the alpha helix, a recurring configuration of protein chains. Their analysis used chemically constrained bond distances and angles, the geometry of peptide groups, and hydrogen bonding to identify feasible helical structures. Pauling and Corey also described the beta sheet. These models explained how chains of amino acids could form regular arrangements without requiring the complete structure of an individual protein to be known beforehand. (pubmed.ncbi.nlm.nih.gov)
In 1949, Pauling, Harvey Itano, S. J. Singer, and Ibert Wells published “Sickle Cell Anemia, a Molecular Disease.” Their experiments demonstrated that hemoglobin from people with sickle cell disease differed in electrophoretic behavior from normal hemoglobin. The findings connected an inherited disorder with an altered protein and established a concrete example of disease explained at the molecular level. The work did not identify the precise amino-acid substitution, which was determined subsequently. (authors.library.caltech.edu)
Not all his structural proposals succeeded. In February 1953, Pauling and Corey published an incorrect three-chain model for nucleic acids, placing phosphate groups near the central axis. Their proposal was superseded by the double-helical model of DNA published that year. (pmc.ncbi.nlm.nih.gov)
Nuclear disarmament and the Peace Prize
Following World War II, Pauling became active in opposition to nuclear weapons and testing. In 1946, he joined the Emergency Committee of Atomic Scientists at Albert Einstein’s invitation. His campaigning emphasized the dangers of radioactive fallout and advocated disarmament amid the Cold War arms race. (lpi.oregonstate.edu)
In January 1958, Pauling and Ava Helen presented the United Nations with a petition against nuclear-bomb testing signed by more than 11,000 scientists. He continued campaigning through public addresses, correspondence, and his book No More War! The Nobel Peace Prize designated for 1962 was announced on October 10, 1963, the day the Partial Test Ban Treaty entered into force. The award recognized his opposition to the nuclear arms race; it did not attribute the treaty solely to his efforts. (lpi.oregonstate.edu)
Later career and vitamin C research
After leaving Caltech in 1964, Pauling held appointments at the University of California, San Diego, and Stanford University. In 1973, he co-founded the Institute of Orthomolecular Medicine, later named the Linus Pauling Institute of Science and Medicine. His later research and public writing increasingly concerned nutrition, including high-dose vitamin C. (lpi.oregonstate.edu)
His 1970 book Vitamin C and the Common Cold popularized claims about supplementation. Subsequent evidence distinguishes these claims from established findings: regular supplementation generally does not prevent colds in the general population, although it can modestly shorten their duration. Pauling also investigated vitamin C in cancer treatment with Ewan Cameron; later controlled trials of oral vitamin C did not reproduce their reported survival benefits. Oral and intravenous administration produce substantially different blood concentrations and are not interchangeable research interventions. (ods.od.nih.gov)
Pauling died at his California ranch in 1994. His papers and those of Ava Helen are preserved at Oregon State University, where the Linus Pauling Institute was re-established in 1996. (lpi.oregonstate.edu)