Linus Pauling

Linus Carl Pauling (February 28, 1901 – August 19, 1994) was an American physical chemist, widely regarded as the premier chemist of the twentieth century. Pauling was a pioneer in the application of quantum mechanics to chemistry, and in 1954 was awarded the Nobel Prize in chemistry for his work describing the nature of chemical bonds. He also made important contributions to crystal and protein structure determination, and was one of the founders of molecular biology. Pauling received the Nobel Peace Prize in 1962 for his campaign against above-ground nuclear testing, becoming the only person in history to individually receive two Nobel Prizes (Marie Curie won Nobel Prizes in physics and chemistry, but shared the former and won the latter individually; John Bardeen won two Nobel Prizes, but both were in the field of physics, and both were shared; Frederick Sanger won two Nobel Prizes in chemistry, but one was shared). Later in life, he became an advocate for regular consumption of massive doses of Vitamin C, a regimen now regarded as medically unorthodox.

Early scientific career

Pauling later traveled to Europe on a Guggenheim Fellowship to study under Arnold Sommerfeld in Munich, Niels Bohr in Copenhagen, and Erwin Schrödinger in Zürich. All three were working in the new field of quantum mechanics. While he was studying at OAC, Pauling was first exposed to the idea of quantum mechanics. He became interested in seeing how it might help in the understanding of his chosen field of interest, the electronic structure of atoms and molecules. In Europe, Pauling was also exposed to one of the first quantum mechanical analyses of bonding in the hydrogen molecule, done by Walter Heitler and Fritz London. Pauling devoted the two years of his European trip to this work and decided to make this the focus of his future research. He became one of the first scientists in the field of quantum chemistry and a pioneer in the application of quantum theory to the structure of molecules. In 1927, he took a new position as an assistant professor at Caltech in theoretical chemistry.

Related Topics:
Europe - Guggenheim Fellowship - Arnold Sommerfeld - Munich - Niels Bohr - Copenhagen - Erwin Schrödinger - Zürich - Quantum mechanics - Electronic structure - Atom - Molecule - Hydrogen - Walter Heitler - Fritz London - Quantum chemistry - 1927 - Professor - Theoretical chemistry

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Pauling began his faculty career at Caltech with a very productive five years, both continuing with his X-ray crystal studies and performing quantum mechanical calculations on atoms and molecules. He published approximately fifty papers in those five years. In 1929, he was promoted to associate professor, and in 1930, to full professor. By 1931, the American Chemical Society awarded Pauling the Langmuir Prize for the most significant work in pure science by a person 30 years of age or younger. In 1932, Pauling published what he regarded as his most important paper, in which he first laid out the concept of hybridization of atomic orbitals and analyzed the tetravalency of the carbon atom.

Related Topics:
X-ray - 1929 - 1930 - 1931 - American Chemical Society - Langmuir Prize - 1932 - Hybridization

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

At Caltech, Pauling struck a close friendship with Robert Oppenheimer, who was spending part of his research and teaching schedule away from Berkeley at Caltech every year. The two men planned to mount a joint attack on the nature of the chemical bond; apparently Oppenheimer would supply the mathematics and Pauling would interpret the results. However, this relationship soured when Pauling began to suspect that Oppenheimer was probably becoming too close to Pauling's wife, Ava Helen. Once, when Pauling was at work, Oppenheimer had come to their place and blurted out an invitation to Ava Helen to join him on a tryst to Mexico. Although she flatly refused, she reported this incident to Pauling. This, and her apparent nonchalance about the incident, disquieted him, and he immediately cut off his relationship with the Berkeley professor, leading to a coolness between them that would last their lives, although Oppenheimer did invite Pauling to be the head of the Chemistry Division of the atomic bomb project. (Pauling refused, saying that he was a pacifist).

Related Topics:
Robert Oppenheimer - Mexico - Atomic bomb project - Pacifist

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

In the summer of 1930, Pauling made another European trip, learning about the use of electrons in diffraction studies similar to the ones he had performed with X-rays. With a student of his, L. O. Brockway, he built an electron diffraction instrument at Caltech and used it to study the molecular structure of a large number of chemical substances.

Related Topics:
1930 - Electron - Diffraction

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Linus Pauling introduced the concept of electronegativity in 1932. Using the various properties of molecules, such as the energy required to break bonds and the dipole moments of molecules, he established a scale and an associated numerical value for most of the elements, the Pauling Electronegativity Scale, which is useful in predicting the nature of bonds between atoms in molecules.

Related Topics:
Electronegativity - Molecule - Dipole - Pauling Electronegativity Scale

~ ~ ~ ~ ~ ~ ~ ~ ~ ~