Biography

Linus Pauling was born on February 28th, 1901 in Portland, USA. His father was a travelling drug salesman, and later opened his own drugstore. Messing about in his father's store, the very young Linus developed a lifelong attachment to chemistry. When in high school, he would salvage material from an abandoned steel plant to build equipment for chemistry experiments. (By the way, Linus Carl sounds similar to Carolus Linnaeus, the name of the scientist who classified all living things into Plant and Animal Kingdoms. But Linnaeus lived two hundred years before Linus!)

He finished his education at Oregon State University, and the California Institute of Technology (Caltech). There he got interested in X-ray crystallography, which would help him win a Nobel Prize later on. He also got interested in quantum physics, travelling to Europe where he met the three giants of the day - Arnold Sommerfeld, Niels Bohr and Erwin Schrodinger. He merged his learnings to form the new science of quantum chemistry.

He was appointed as a Professor of Chemistry at Caltech, where he stayed for the rest of his life. He died on August 19th, 1994.

Chemistry

Much of what we know of the nature of molecules is because of Linus Pauling. He used quantum chemistry to investigate electrovalent bonds (made by transferring electrons from one atom to another) and covalent bonds (uncharged bonds made by sharing electrons). He found that most molecules are actually made of bonds that are neither fully electrovalent nor covalent.

We often see drawings of atoms that look like tiny solar systems - electrons orbiting the nucleus. The true picture is that electrons are more like a cloud of negative charge. And Pauling found that when an atom forms bonds with another atom, the clouds rearrange themselves into hybrid orbitals that cover the nuclei of both. Pauling wrote a textbook in 1939 called the Nature of the Chemical Bond. Even today, chemists around the world consider it the greatest chemistry book ever written. His work on the chemical bond got him his first Nobel Prize, for Chemistry in 1954.

Water is formed by a covalent bond between two hydrogen atoms and one oxygen atom. But the electrons are not shared equally. The bigger oxygen atom pulls the shared electrons towards itself, so it gets a negative charge. The hydrogen atoms have to go unbalanced, so they get a tiny positive charge. They try to balance this by forming bonds with oxygen atoms from other water molecules (called hydrogen bonds). Hydrogen bonds explain a few curious properties of water, like why it expands when freezing.

Proteins

Pauling was among the first to start studying proteins using X-ray crystallography. Proteins are strings of amino acids that are then folded up in different shapes. He figured out that most proteins come in two shapes - corkscrews and zig-zags. {Since scientists prefer fancier names, they are called alpha helices and beta sheets}.

His big miss in life was that he thought DNA was made of a triple helix (he imagined it to be like three strings plaited together). But he did not have X-ray pictures as good as Rosalind Franklin's. Thus the credit for that went to Watson, Crick and Wilkins. But Pauling made other important discoveries, like how enzymes work, and what causes sickle cell anaemia. It is because of Pauling's efforts that studying the structure of biomolecules is an important part of biology today.

Peace

The atomic bombings of Hiroshima and Nagasaki disturbed Linus Pauling. He joined Bertrand Russell and Albert Einstein to campaign against the use and testing of nuclear weapons. He supported a scientific study that showed the dangers of radioactivity that came from testing nuclear weapons. 11,000 scientists headed by Pauling submitted a petition to the United Nation is 1958, asking for an end to nuclear testing.

The US government thought that he was being unpatriotic, since they were in a nuclear weapons race with the USSR. But as public awareness of the dangers of nuclear weapons grew, the government had to backtrack. In 1962, USA signed a treaty with the USSR, in which both countries agreed to stop some kinds of nuclear testing. For his influence on getting the treaty signed, Pauling was awarded the Nobel Prize for Peace in 1962.