Who he was
Linus Pauling grew up in Oregon, lost his father at the age of nine and worked at many jobs to pay for his education. He spent most of his career at Caltech, where he combined X-ray crystallography with the new quantum mechanics to answer one of chemistry’s oldest questions: what holds atoms together?
Key contributions
The chemical bond. Pauling used quantum mechanics to explain why bonds form and why molecules have the shapes they do. His idea of hybrid orbitals explains why the four bonds in methane point to the corners of a tetrahedron, at 109.5° to each other. His idea of resonance explains molecules, such as benzene, that no single Lewis structure describes well.
Electronegativity. In 1932 he introduced a scale of how strongly an atom attracts the electrons in a bond. Fluorine is the most electronegative element, with a value of 4.0 on his scale. The difference in electronegativity between two atoms tells you whether a bond is non-polar covalent, polar covalent or mostly ionic.
Key idea
Electronegativity is a single number that connects the periodic table to bonding. When the difference between two atoms is small, the electrons are shared; when it is large, one atom effectively takes them, and the bond is ionic.
The molecules of life. Pauling turned to biology. He showed that sickle-cell anaemia comes from a change in one protein molecule, and in 1951 he proposed the alpha helix, the coiled shape of many protein chains. He also proposed a structure for DNA, a triple helix, which turned out to be wrong; Watson and Crick’s double helix followed in 1953.
Prizes and legacy
He won the 1954 Nobel Prize in Chemistry for his research into the nature of the chemical bond, and the 1962 Nobel Peace Prize for his campaign against nuclear weapons testing. He is the only person to have won two Nobel Prizes that were not shared with anyone else. In later life he promoted large doses of vitamin C, a claim that later research did not support: a reminder that even great scientists must follow the evidence.
Connections to your lessons
You use his ideas in the lessons on periodic trends (electronegativity), ionic and covalent bonds (bond polarity), molecular shapes (hybridization and bond angles) and Lewis structures (resonance).
Timeline
- 1901Born in Portland, Oregon.
- 1922Graduates in chemical engineering from Oregon Agricultural College (now Oregon State University).
- 1925Earns his PhD at Caltech, using X-ray crystallography to find the structures of crystals.
- 1926Travels to Europe to learn the new quantum mechanics from its founders.
- 1931Publishes "The Nature of the Chemical Bond", introducing hybrid orbitals to explain the shapes of molecules such as methane.
- 1932Introduces the electronegativity scale, with fluorine the most electronegative element.
- 1939Publishes the book The Nature of the Chemical Bond, one of the most cited science books of the century.
- 1949With co-workers, shows that sickle-cell anaemia is caused by an abnormal haemoglobin molecule, the first "molecular disease".
- 1951With Robert Corey and Herman Branson, proposes the alpha helix and beta sheet, the main shapes of protein chains.
- 1954Awarded the Nobel Prize in Chemistry.
- 1958With his wife Ava Helen Pauling, presents a petition signed by over 9000 scientists against nuclear weapons tests to the United Nations.
- 1963Receives the 1962 Nobel Peace Prize on the day the Partial Nuclear Test Ban Treaty comes into force.
- 1994Dies at his ranch at Big Sur, California.
Sources and further reading
Explore next
Dorothy Crowfoot Hodgkin
1910–1994
Dorothy Hodgkin (1910–1994) used X-ray crystallography to solve the structures of penicillin, vitamin B12 and insulin, and won the 1964 Nobel Prize in Chemistry.
Frederick Sanger
1918–2013
Frederick Sanger (1918–2013) determined the amino acid sequence of insulin and invented the main method for reading DNA, winning the Nobel Prize in Chemistry in 1958 and again in 1980.
Spotted a mistake? Let us know and we'll fix it.