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Pauling, Linus (Carl)

chemical structures chemistry bond

[paw ling] (1901–94) US chemist: the outstanding chemist of the 20th-c.

Pauling’s chemical beginnings were very ordinary. He grew up in a country area in Oregon, and his father (a pharmacist) died when he was 9; the boy began experimenting with chemicals when he was 11 and continued at school. By 15 he had decided to become a chemical engineer. He attended the small Oregon Agricultural College and did well enough (especially in chemical analysis) to be paid to teach first-year students. He went on to the California Institute of Technology, working for his PhD on X-ray studies of inorganic crystals. He read intensively and his memory was remarkable. He began to develop a scheme to assign sizes to atoms in crystals, and used these dimensions to work out the structures of a wide range of minerals, including eventually the silicates and some other major groups which had previously been seen as a structural mystery. After his PhD in 1925, he spent 2 years studying in Europe, mainly in Germany with . This led him to an extensive study of the use of quantum theory in understanding chemical bonds. By the early 1930s he had largely developed the valence-bond (VB) approach to bonds, using concepts such as ‘hybridization’ of bonds and ‘resonance’ for calculating bond energies, lengths and shapes and magnetic properties. He also devised an electronegativity scale, valuable in predicting bond strength. From his return to Caltech in 1927 he held a position there for 35 years, together with others in California.

In the 1930s he began to work on biochemical problems, beginning with X-ray studies on the precise shape of amino acids and peptides. From this he went on to deduce two model structures for proteins: these are the ‘pleated sheet’ and ‘a-helix’ types, both found in important biological structures. Other ventures in biochemistry included theories of the chemical basis of anaesthesia and of memory; and with he studied the structure and action of antibodies. Here he used the new idea of ‘complementary structures in juxtaposition’. This last idea, together with his ideas on helical structures in biomolecules and on hydrogen-bonding as an important determiner of their shape, form the key aspects of model of DNA as a self-replicating double helix. Also in the 1940s he proposed that sickle-cell disease (a genetic anaemia) resulted from a change in the normal amino acid content of haemoglobin; proof of this gave the earliest example of a disease being traced to its precise origin at the molecular level.

Pauling’s work has generated some controversy: his views on the value of a high vitamin C level in the diet in combating a range of ills from the common cold to old age are not universally accepted and his political views in pursuit of world peace led to problems (his passport was withheld for a time). He won two Nobel Prizes; for chemistry in 1954, and for peace in 1962. His elementary texts remain among the best available.

His work in science is exceptional in its range, covering inorganic and organic chemistry, theoretical chemistry and practical devices, work on minerals and in biology. His work in chemistry is without peer in the 20th-c in its vitality, vision and significance. His contributions to novel chemical theory continued in his 80s.

Pavlov, Ivan Petrovich [next] [back] Pauli, Wolfgang

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