Gilbert N. Lewis

AMERICAN PHYSICAL CHEMIST
1875–1946

Gilbert Newton Lewis was born on October 25, 1875, in West Newton, Massachusetts. A precocious child, he received his early education at home and learned to read by the age of three. When Lewis was nine, his family moved to Lincoln, Nebraska. He attended the University of Nebraska for two years and in 1893 transferred to Harvard University, from which he received his B.S. in 1896.

After a brief stint as a teacher at Phillips Academy in Andover, Massachusetts, Lewis returned to Harvard, where he obtained his M.A. in 1898 and Ph.D. in 1899. He subsequently studied at the universities at Göttingen and Leipzig in Germany (1900–1901) and then returned to Harvard as an instructor (1901–1906). In 1907 Lewis became an assistant professor at the Massachusetts Institute of Technology, where he soon rose to the rank of full professor.

American chemist Gilbert N. Lewis, a theorist of chemical bonds, or valence.

In 1912 Lewis accepted a position as dean and chairman of the College of Chemistry at the University of California, Berkeley. He remained at Berkeley for the rest of his life and transformed the chemistry department there into a world-class center for research and teaching. His reforms in the way chemistry was taught, a catalyst for the modernization of chemical education, were widely adopted throughout the United States. Lewis introduced thermodynamics to the curriculum, and his book on the same subject became a classic. He also brought to the study of physical chemistry such concepts as fugacity, activity and the activity coefficient, and ionic strength.

At the beginning of the twentieth century physicists tried to relate the electronic structure of atoms to two basic chemical phenomena: the chemical bond (the attraction between atoms in a molecule) and valence (the quality that determines the number of atoms and groups with which any single atom or group will unite chemically and also expresses this ability to combine relative to the hydrogen atom). German chemist Richard Abegg was the first to recognize in print the stability of the group of eight electrons, the arrangement of outer electrons that occurs in noble gases and is often attained when atoms lose or gain electrons to form ions. Lewis called this the "group of eight," and American chemist and physicist Irving Langmuir labeled it an "octet."

In 1902, while explaining the laws of valence to his students at Harvard, Lewis conceived a concrete model for this process, something Abegg had not done. He proposed that atoms were composed of a concentric series of cubes with electrons at each of the resulting eight corners. This "cubic atom" explained the cycle of eight elements in the Periodic Table and corresponded to the idea that chemical bonds were formed by the transfer of electrons so each atom had a complete set of eight electrons. Lewis did not publish his theory, but fourteen years later it became an important part of his theory on the shared electron-pair bond.

In 1913 Lewis and Berkeley colleague William C. Bray proposed a theory of valence that differentiated two different types of bond: a polar bond formed by the transfer of electrons and a nonpolar bond not involving electron transfer. In 1916 Lewis published his seminal article suggesting that the chemical bond is a pair of electrons shared or held jointly by two atoms. He depicted a single bond by two cubes sharing an edge, or more simply by double dots in what has become known as Lewis dot structure.

According to Lewis's octet rule, each atom should be surrounded by four pairs of electrons, either shared or free pairs. Lewis derived structures for halogen molecules, the ammonium ion, and oxy acids, inexplicable according to previous valence theories. He viewed polar bonds as unequally shared electron pairs. Because the complete transfer of electrons was only an extreme case of polarity, he abandoned his earlier dualistic view; the polar theory was just a special case of his more general theory.

Lewis's shared electron-pair theory languished until Langmuir revived and elaborated it beginning in 1919. It was soon accepted as the Lewis–Langmuir theory, one of the most fundamental concepts in the history of chemistry.

Lewis's acid-base concept is also well known to introductory-level chemistry students. A Lewis acid, for example, BF ₃ , AlCl ₃ , or SO ₃ , is a substance that can accept a pair of electrons from a Lewis base, for example, NH ₃ or OH−, which is a substance that can donate a pair of electrons. It can be applied to various areas, for example, coordination chemistry : The metal ion is a Lewis acid, the ligand is a Lewis base, and the resulting formation of a coordinate covalent bond corresponds to a Lewis acid–base reaction.

Lewis made additional valuable contributions to the theory of colored substances, radiation, relativity, the separation of isotopes , heavy water, photochemistry, phosphorescence, and fluorescence. As a major in the U.S. Army Chemical Warfare Service during World War I, he worked on defense systems against poison gases. From 1922 to 1935 he was nominated numerous times for the Nobel Prize in chemistry. Lewis's death, while measuring the dielectric constant of hydrogen cyanide on March 23, 1946, precluded his receiving the prize, which is not awarded posthumously.

SEE ALSO Acid-Base Chemistry ; Lewis Structures .

George B. Kauffman

Bibliography

"Gilbert Newton Lewis: 1875–1946." Papers presented at the 183rd National Meeting of the American Chemical Society, Las Vegas, NV. Journal of Chemical Education 61: (January 1984) 3–21, (February 1984) 93–116, (March 1984) 185–215.

Hildebrand, Joel H. (1958). "Gilbert N. Lewis." Biographical Memoirs, National Academy of Sciences 31:209–235.

Leicester, Henry M., ed. (1968). Source Book in Chemistry 1900–1950, pp. 100–106. Cambridge, MA: Harvard University Press.

Lewis, Edward S. (1998). A Biography of Distinguished Scientist Gilbert Newton Lewis. Lewiston, NY: Edwin Mellen Press.

Lewis, Gilbert N. (1916). "The Atom and the Molecule." Journal of the American Chemical Society 38:762–785.

Lewis, Gilbert Newton (1923). Valence and the Structure of Atoms and Molecules. New York: Chemical Catalog Co. Reprinted, New York: Dover, 1966.

Lewis, Gilbert Newton, and Randall, Merle F. (1923). Thermodynamics and the Free Energy of Chemical Substances. New York: McGraw-Hill.