Gilbert N. Lewis

American physical chemist

• Born: October 23, 1875; Weymouth, Massachusetts
• Died: March 23, 1946; Berkeley, California

Physical chemist Gilbert Lewis is known for his contributions to the chemical study of thermodynamics, the discovery of the covalent bond, and his contributions to the discovery of deuterium and heavy water. Lewis spent most of his career teaching at the University of California, Berkeley where he trained a number of doctoral students who went on to make other major contributions to the field of chemistry.

Primary field: Chemistry

Specialty: Thermodynamics

Early Life

Gilbert Newton Lewis was born on October 23, 1875 in Weymouth, Massachusetts, the son of Frank and Mary Lewis. The family moved to Nebraska when Lewis was nine years old, where his father worked as a lawyer and later a banker. Lewis and his two siblings were homeschooled by their mother, who gave them an early education on a variety of topics, including math and science. Lewis began his undergraduate work at the University of Nebraska but transferred to Harvard University when his family relocated to Boston in 1892. Lewis graduated with a bachelor’s degree in chemistry in 1895 and entered a PhD program at Harvard under the direction of chemist Theodore Richards. Lewis’s doctoral dissertation covered two subjects: the utilization of zinc and cadmium as electrodes, and a theoretical exploration of issues of free energy in chemical thermodynamics.

After earning his PhD, Lewis traveled abroad for further study, working in the laboratories of German chemist Wilhelm Ostwald at Leipzig University and German physicist Walther Nernst at Göttingen University. In 1907, Lewis received a full professorship at the Massachusetts Institute of Technology (MIT), where he remained until 1912, when he was offered the chance to chair the chemistry department at the University of California, Berkeley. Lewis remained in California for the remainder of his career, helping to transform UC Berkeley’s chemistry department into one of the most respected in the country.

Life’s Work

Early in his career, Lewis focused on thermodynamic research. Among his most lasting contributions to this branch of chemistry was the book Thermodynamics and the Free Energy of Chemical Systems, published in 1923, and coauthored by chemist Merle Randall. Lewis and Randall’s text was one of the first books to present thermodynamic principles to undergraduate chemistry students. It is considered a milestone of educational literature in the field. While he was working on his doctorate, Lewis produced a paper explaining his theories on thermodynamics and free energy that was rejected by his advisor and other professors at Harvard. However, the ideas he developed in this paper were later verified. Lewis also introduced the term “fugacity” to the field of chemical thermodynamics while conducting his doctoral work, to describe a property of a gas related to its tendency to escape or expand.

Lewis’s best-known contribution to chemistry came with the 1916 publication of his now famous paper “The Atom and the Molecule,” in which he proposed a new mechanism for covalent bonding, a type of chemical bond involving atoms that share pairs of electrons. At the time, the only type of molecular bond known to scientists was the “ionic bond,” in which negatively and positively charged atoms become attracted to one another because of their complimentary charges. Lewis proposed that it would be possible for atoms to “share” a single pair of electrons, thereby stabilizing the valence shell of both atoms while simultaneously creating a strong bond between them. Lewis called this “covalent bonding.” He introduced new ideas discussing how covalent bonding functions in the formation of various molecules. This discovery was a major step in the development of physical chemistry, bringing about a new understanding of molecular structure.

Lewis’s work on covalent bonding also produced the now ubiquitous “Lewis dot diagrams,” a conceptual way to envision atoms, using dots to represent electron pairs and lines between chemical symbols to represent covalent bonds. The dot diagrams remain an important modeling method in physical chemistry.

In the early 1920s, Lewis studied the chemistry of acidic reactions and created a new model to explain the basic interaction between acids and bases. At that time, Swedish chemist Svante Arrhenius and Danish chemist Johannes Brønsted had defined acid–base reactions as reactions in which one substance, termed the “acid,” accepts protons from a proton donating substance, called a “base.” According to this definition, only substances with a relationship to hydrogen (the “proton” donated in acid–base reactions), could be chemically understood.

Lewis expanded on this model, proposing that any substance that can accept or donate an electron pair can be considered an acid or base, respectively. Lewis published the results of this theory in 1923 and continued to produce research utilizing his theory into the late 1930s. Because of Lewis’s work on this subject, chemists now use the term “Lewis acid” and “Lewis base” to describe substances capable of acting as acids and bases through the donation of electron pairs. Lewis’s expansion of the acid–base model allowed chemists to evaluate a variety of reactions occurring between atoms that have no relationship to hydrogen and this was a significant expansion in the general understanding of chemical reactions.

In the late 1920s, many of the nation’s leading chemists were involved in the search for isotopes of the lighter elements, such as hydrogen. While these isotopes were suspected to exist, chemists had not yet been able to isolate the substances in experimental conditions. Lewis’s graduate student Harold Urey was the first to isolate deuterium, an isotope of hydrogen that has an additional neutron, while the standard variety had no neutrons. Urey was able to spectrographically demonstrate deuterium in 1931, and shortly thereafter Lewis managed to create “heavy water,” which is a sample of water in which most of the water molecules have deuterium substituted for standard hydrogen. The discovery of heavy water was an important contribution to physical chemistry, and the substance became important in a variety of industrial processes. For instance, heavy water is utilized in nuclear reactors to aid in the production of plutonium, and it is also used in biological marking experiments that employ deuterium to trace the path of molecules through the body.

Impact

One of Lewis’s most significant contributions to science was his role in fostering the development of the chemistry department at the University of California, Berkeley. Biographical accounts indicate that Lewis’s experience as a PhD candidate was unpleasant because Richards curtailed the research programs of his students. Lewis later accused Richards of having taken credit for research conducted by his students. Perhaps in response to this, Lewis worked to create an open, communicative environment that allowed doctoral students greater freedom in terms of research schedules, subjects, and mentorship. Lewis is credited with laying the foundations for what became a highly creative and productive research institution at the university.

Lewis was a scholar of wide-ranging interests. Although his primary impact was in physical chemistry, he also published articles on physics, geology, and sociology.

Lewis’s research on acid-base reactions and his discovery and definition of the covalent bond were major milestones in theoretical and physical chemistry. During his career, Lewis produced more than 160 publications, making him among the most prolific researchers of his era.

A rivalry between Lewis and Nernst may have prevented Lewis from achieving his lifelong goal of winning a Nobel Prize. Nernst is alleged to have influenced his friend, Swedish electrochemist and Nobel Prize Committee member Wilhelm Palmaer, to work against Lewis’s Nobel nomination. Palmaer may have objected to Lewis’s nomination in his own right because Lewis’s work on thermodynamics contradicted much of his own research. Though Lewis was nominated for a Nobel Prize on more than thirty occasions, he never earned the Nobel Prize, and this caused him a considerable amount of personal pain. Lewis was elected to the National Academy of Sciences in 1913, but he resigned from the organization in 1934, possibly in protest of having been prevented from receiving a Nobel Prize.

Lewis was discovered dead in his laboratory in 1946, in what was considered an accidental death due to his working with a solution containing hydrogen cyanide. Some have speculated, since his death, that Lewis may have committed suicide because of his frustration with the politics of the scientific community, and his failure to achieve popular recognition for his research.

Bibliography

Atkins, Peter. Reactions: The Private Life of Atoms. New York: Oxford UP, 2011. Print. Presents a variety of informative sections detailing the processes, discoveries, and applications of various chemical reactions. Discusses Lewis acid and base pairs and their role in chemical and physical reactions.

Coffey, Patrick. Cathedrals of Science: The Personalities and Rivalries that Made Modern Chemistry. New York: Oxford UP, 2008. Print. Provides biographical and historical information on a number of chemists during the turn of the century and discusses their lives, relationships, and role in the creation of chemistry research. Includes detailed biographical information on Lewis’s life, research, and death.

Dahl, Per F. Heavy Water and the Wartime Race for Nuclear Energy. Bath, UK: Institute of Physics, 1999. Print. Discusses the chemical and military research into heavy water and deuterium and its relationship to the development of nuclear energy technology. Contains a discussion of Lewis’s role in the isolation of heavy water and his other research regarding deuterium.