American quantum chemist, biochemist, and peace advocate. As a graduate student at the California Institute of Technology, he studied X-ray diffraction of crystals with Rosco Dickinson. Curiously enough, Pauling had never even received his high school diploma because he refused to take a course in civics.

Pauling was an innovator in many aspects of chemistry. As one acquaintance remarked, "Linus's bad ideas are better than most people's good ones." (Serafini 1991, p. 101). In 1925, he won a Guggenheim fellowship which he used to study under Sommerfeld at Munich. Soon after his return, he became a professor at Caltech.

Early in his career, Pauling published "The Theoretical Prediction of the Physical Properties of Many Electron Atoms and Ions," which demonstrated that the structure of electron orbitals in complicated atoms could be described with quantum mechanics. In 1928, he set down the six Pauling's rules governing the placement of atoms in ionic solids. In 1928, he published a paper on orbital hybridization (resonance structures). In 1931, he published "The Nature of the Chemical Bond," which became the basis for his book of that title published in 1932. This book was the first to apply quantum mechanics to chemistry. In a 1936 paper with Coryell, he reported that hemoglobin in arteries is repelled by a magnet, but that in veins is attracted. In another 1936 paper, this one with Mirsky, he proposed that proteins were polypeptides. This proposal led to a simple explanation of denaturation (breakdown).

After the death of Noyes, Pauling became chairman of the Division of Chemistry and Chemical Engineering at Caltech. In 1937, he gave the Baker lecture at Cornell. Shortly thereafter, he entered into a heated disagreement with Dorothy Wrinch on the merits of her cyclol theory of proteins compared to his alpha helix theory. The basis for Pauling's choice of a helical model were his experiments which showed the peptide bond to be planar, together with considerations of the X-ray diffraction data. A hostile meeting with Wrinch in Ithaca in January 1938 did not help matters. Finally, in his 1939 paper with Niemann "The Structure of Proteins," he demolished the cyclol theory.

During the 1940s, Pauling worked on sickle cell anemia, a search for a helical structure of DNA, and solution to protein architecture. He intuitively concluded correctly that sickle cell anemia was a disease of the hemoglobin molecule. In the fall of 1940, he became very ill with glomerules nephritis (Bright's disease), which continued to flare up in subsequent years. In 1941, he received an offer to be director of Research of the Shell Development Company, but he turned it down. Among his other activities, Pauling developed a theory in which electron pairs formed a stabler and less energetic system. Pauling also invented the concept of electronegativity , a ranking of the tendency of an atom to gain electrons.

During World War II, he practically abandoned his scientific work and began to get involved in controversial political activities. In particular, he objected to mandatory loyalty affirmations, and so was accused on being un-American and, by extension, communist. This unjustified label prevented the state department from granting him a passport to attend the 1951 "Structure of Proteins" conference in England. Finally, on his third attempt to get a passport, he asked for and received a note from Einstein to the President.

Pauling continued to search for the structure of DNA . However, his alpha helix was single stranded and did not repeat in an integral number of turns. Perhaps had he been allowed to travel to England and see first hand the work of Crick, James Watson, and Wilkins, he might have seen he was barking up the wrong tree. Instead, in a 1953 paper he published with Corey "A Proposed Structure fro the Nucleic Acids," which contained a number of glaring errors. Not only was the phosphate backbone on the inside instead of the outside, but the positions he assigned to the hydrogen atoms made his structure not even an acid! Pauling's political activities continued in the 50s with his publication of No More War! (1953). This further inflamed the State Department. Nevertheless, when he was awarded the 1954 Nobel Prize in chemistry for his work in the helical structure of proteins and chemical bonding, the State Department was forced to relent and grant him an exit visa.

After accepting the Nobel Prize, he cut back on his research and began more speculative work, including his controversial work on vitamin C. At this time, he was living at 3500 Fairpoint Street in Pasadena. Unfortunately, he began requisitioning too much space in Church chemistry lab in the mid-50s to early 60s, to the point where the lab space was finally taken away. Pauling resigned as Chairman in 1958 and began applying himself to his political activities. This time, he lobbied to ban nuclear tests. His new work did not endear him with politicians, and he was investigated by the Senate Internal Security Committee in 1960 on the "evidence of serious Communist infiltration in the various movements urging a nuclear test ban." However, his stubborn pertinacity culminated in the nuclear test ban treaty in 1963 and the Nobel Peace Prize of 1964. With two Nobel Prizes, Pauling is a member of an elite group of only four scientists: Pauling, Bardeen, Sanger, and Marie Curie. Pauling's politicking is discussed in Mildred and Victor (1980).

After receiving the 1964 Peace Prize, he left Caltech under growing fire from the Institute for his increasing lab usage and inflammatory politics. He first went to the Center for Democratic Institutions, where he stayed here for there years, although what he accomplished there remains somewhat of a mystery. In 1967, he revised The Nature of the Chemical Bond, with the new edition simply entitled The Chemical Bond (1967).

Pauling spent 1967-1969 at the University of California San Diego, then moved to Stanford where he plunged into his "research" on vitamin C as a prevention of cancer and the common cold. He published Vitamin C and the Common Cold. Finally, he founded the Linus Pauling Institute near the Stanford Linear Accelerator in Menlo Park. He continued his work on vitamin C, and published How to Live Longer and Feel Better (1990). Pauling soon encountered further problems when he tried to dismiss Robinson, whom he had previously given a tenured position at the Institute. This action seems to have arisen from resentment that Robinson was independently carrying out experiments on the effects of vitamin C on tumors in mice. Pauling settled the dispute out of court in 1983, but the motivation behind his harsh action is still unclear.