Geology 310—Mineralogy

Linus Pauling

Linus Carl Pauling (February 28, 1901 – August 19, 1994) was an American quantum chemist and biochemist. He was also acknowledged as a crystallographer, molecular biologist, and medical researcher. Pauling is regarded as one of the premier chemists of the twentieth century. He pioneered 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. He came near to discovering the "double helix," the ultrastructure of DNA, which Watson, Crick, and Franklin discovered in 1953. Pauling is noted as a versatile scholar for his expertise in inorganic chemistry, organic chemistry, metallurgy, immunology, anesthesiology, psychology, debate, radioactive decay, and the aftermath of nuclear warfare, in addition to quantum mechanics and molecular biology.

Pauling received the Nobel Peace Prize in 1962 for his campaign against above-ground nuclear testing, and is the only person to win two Nobel prizes that were not shared with another recipient. The other people who have received two Nobel prizes are Marie Curie (physics and chemistry), John Bardeen (both in physics) and Frederick Sanger (both in chemistry). Later in life, he became an advocate for greatly increased consumption of vitamin C and other nutrients. He generalized his ideas to define orthomolecular medicine, which is still regarded as unorthodox by conventional medicine. He popularized his concepts, analyses, research and insights in several successful but controversial books centered around vitamin C and orthomolecular medicine.

Pauling's rules

Pauling's rules are five rules developed by Linus Pauling for determining the ionic structures of complex crystals.

1. A coordinated polyhedron of anions is formed about each cation, the cation-anion distance determined by the sum of ionic radii and the coordination number (C.N.) by the radius ratio.

2. An ionic structure will be stable to the extent that the sum of the strengths of the electrostatic bonds that reach an anion equal the charge on that anion.

3. The sharing of edges and particularly faces by two anion polyhedra decreases the stability of an ionic structure.

4. In a crystal containing different cations, those of high valency and small coordination number tend not to share polyhedron elements with one another.

5. The number of essentially different kinds of constituents in a crystal tends to be small.