Linus Pauling

Linus Carl Pauling was born on February 28, 1901, in Portland, Oregon. His father, a pharmacist, died when Pauling was nine, and he grew up in modest circumstances. He showed an early aptitude for chemistry and enrolled at Oregon Agricultural College (now Oregon State University), graduating in 1922. He then moved to the California Institute of Technology, where he completed his doctorate in physical chemistry and mathematical physics in 1925, working with Roscoe Dickinson and Richard Tolman.

A postdoctoral fellowship allowed Pauling to study in Europe, where he encountered the new quantum mechanics being developed by Werner Heisenberg, Erwin Schrödinger, and others. Returning to Caltech, he applied quantum mechanical methods to the problem of chemical bonding, producing a series of landmark papers throughout the 1930s.

Pauling introduced the concept of resonance in chemistry, showing that many molecules are best described as intermediate between two or more classical structures. He developed the concept of electronegativity, which quantifies an atom's tendency to attract electrons. He proposed the hybridization of atomic orbitals to explain molecular geometry, and he articulated five key rules governing the structure of ionic crystals that became known as Pauling's rules. His 1939 book The Nature of the Chemical Bond synthesized much of this work and became one of the most cited scientific works of the twentieth century.

In the early 1950s, Pauling turned to the structure of proteins. Using X-ray crystallography data and molecular model building, he and Robert Corey proposed the alpha helix and beta sheet as fundamental secondary structures of proteins in 1951, a breakthrough in structural biology. He also made an early but ultimately incorrect proposal for a triple-helix structure of DNA.

In 1954, Pauling received the Nobel Prize in Chemistry. During the 1950s, he became an outspoken campaigner against nuclear weapons testing, collecting signatures from thousands of scientists and presenting a petition to the United Nations. In 1962, he was awarded the Nobel Peace Prize, making him the only person to win two unshared Nobel Prizes.

In his later years, Pauling promoted large doses of vitamin C, a position that generated controversy within the scientific community. He founded the Linus Pauling Institute of Science and Medicine in 1973.

Linus Pauling died on August 19, 1994, in Big Sur, California.