Glenn T. Seaborg, 1912-1999

Linus Pauling and Glenn Seaborg with three young science students, American Chemical Society Meeting, St. Louis, April 1984.

“I hardly noticed that the work was exacting and demanding, because I couldn’t believe that I was being paid to do what I would have chosen as a hobby. It was exciting just to walk into the lab, full of anticipation that that day I might be the first human being ever to see some unimaginable new creation.“

–Glenn Seaborg

Advising nine presidents on nuclear policy as the Chairman of the U.S. Atomic Energy Commission, Glenn T. Seaborg, whose centenary we celebrate today, contributed to the discovery and isolation of ten elements, was the author of 500 scientific articles, father of six kids and, most notably, the recipient of the 1951 Nobel Prize in Chemistry. Gaining international fame over the course of his career, Seaborg is best known for discovering the element plutonium in 1941, as well as nine other new transuranic elements.

Seaborg describes the search for Plutonium, “element 94.”

Alongside Edwin McMillan, Seaborg received the Nobel Prize in Chemistry for discoveries in the structure and function of the transuranium elements. In addition, Seaborg and his colleagues can be credited for the identification of more than 100 isotopes of elements throughout the periodic table. At the time that he was publishing it, Seaborg’s work required a major realignment of the periodic table of the elements, which was naturally controversial among his contemporaries, but Seaborg was willing to take a risk and it paid off. On hearing the news that he had received the Nobel Prize in Chemistry, Seaborg was quoted as saying,

One November morning as I drove to work, the radio cackled with news of my reward for taking this chance – the 1951 Nobel Prize in chemistry shared with colleague Ed McMillan. At 39, I was one of the youngest winners ever of the world’s most prestigious award.

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“Education is the best investment we can make in the future, and like any investment, it costs money. We can’t continue to pretend that it doesn’t. We must invest money for buildings, money for supplies, money to improve the curriculum, and money to pay teachers a salary that will attract our brightest people to the profession.“

-Glenn Seaborg

Glenn Theodore Seaborg was born in Michigan on April 19, 1912. Ten years later, his family moved to California in search of opportunity. Seaborg graduated as class valedictorian from David Starr Jordan High School and continued his studies at UCLA. Attending graduate school at the University of California-Berkeley, Seaborg blossomed as a scientist, noting

By day I ran experiments on acids and bases as the personal assistant of cigar-chewing Gilbert N. Lewis, the world’s pre-eminent physical chemist. And by night I spent my free time exploring the mysteries of the atom.

Receiving his Ph.D. in chemistry in 1937, Seaborg continued on as laboratory assistant to G. N. Lewis, who was himself an important mentor to Linus Pauling. In 1939 he was hired as an instructor of chemistry at Berkeley, later becoming Professor of Chemistry.

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“Most of my scientific work has been basic research. There were no immediate uses for my discoveries – but today the radioisotopes are the workhorses of nuclear medicine, an isotope of plutonium is a major energy source in the space program, and the element americium is critical to the smoke detectors in every house in the country. The cost of neglecting basic research will be a continued decline in America’s technological innovation and competitiveness.“

-Glenn Seaborg

In 1958, seven years after his receipt of the Nobel Chemistry Prize,  Seaborg was named Chancellor of the University of California-Berkeley.  Over the course of his short chancellorship, the university saw an increase in enrollment as well as in student activism – a harbinger of things to come in Berkeley.

Three years later, in 1961, he was appointed by President John F. Kennedy to the Atomic Energy Commission. During this time, Seaborg pushed for commercial nuclear energy and peaceful applications of nuclear science. He believed his most significant achievement while at the AEC to be the growth of the civilian nuclear power program.

Notes from a Pauling speech, "The Bomb Test Controversy and World Peace." November 1, 1962.

While Pauling’s feelings on these issues were mixed, and his relationship with the AEC often combative, it is clear that on other matters of nuclear policy, he and Seaborg shared common ground.  In a 1986 typescript, Pauling recalled

At a recent national meeting of the American Chemical Society, held in St. Louis, Glen Seaborg and I participated in a press conference, with many reporters and television crews present.  Seaborg, who had been Chairman of the Atomic Energy Commission, accompanied the United States negotiators when the partial bomb test treaty was made [in 1963].  The Soviet Union was eager to make a comprehensive bomb test treaty, but the administration in Washington, Seaborg said, had instructed the U.S. team not to agree to a comprehensive test ban, which would hamper seriously the program of continually developing new nuclear weapons.

Indeed, throughout his career, Seaborg corresponded with Linus Pauling on a number of issues, including the investigation of uranium hexafluoride and mutual congratulations shared on the occasion of one another’s Nobel Prizes. In May 1969, when Pauling was made an Honorary Member of the American Institute of Chemists, Seaborg wrote, “Your accomplishments had already qualified you for such an honor and your work during the intervening years of our friendship has added much to this early distinction.”

On April 13, 1981, Seaborg visited Oregon State University as part of a lecture series on “Technology and Change.”  While in Corvallis, he led a seminar titled “The Transuranium Elements,” as well as public talk titled, “Our Energy Problem.” One of the transuranium elements that Seaborg discussed in his seminar, element 106, was named “seaborgium” in August 1997, making it the first element to be named for a living person.

Just before his death on February 25, 1999, the ultimate result of a stroke, Seaborg’s lifetime of achievement was honored by the American Chemical Society, who named him one of the “Top 75 Distinguished Contributors to the Chemical Enterprise.”  Seaborg was among the top four vote-getters for this decoration, joining Robert B. Woodward, Wallace Carothers and, in first place, Linus Pauling, at the top of the list.

Developing the Theory of Resonance

Linus Pauling, 1930.

[Part 1 of 2]

“I think my work on the chemical bond probably has been most important in changing the activities of chemists all over the world – changing their ways of thinking and affecting the progress of the science.”

Linus Pauling, 1977.

In early 1932, Linus Pauling spent several months visiting the University of California, Berkeley and the Massachusetts Institute of Technology to present two different lecture series on the theory of resonance and its implications for molecular structure and function. This topic, a product of Pauling’s adventures in Europe as a Guggenheim fellow, would profoundly impact the ways in which twentieth-century chemists ultimately understood the chemical bond and predicted molecular structures.

Throughout his long career, Pauling sought to improve his understanding of molecular structure in order to better predict chemical function. As Pauling saw it, molecular structure dictates function and should thus be considered accordingly.  As he wrote in 1946

…I am confident that, as our knowledge of the structure not only of simple molecules but also of proteins and other complex constituents of organisms increases, we shall in time achieve an insight into physiological phenomena which will serve as an effective guide in biological and medical research, and will contribute to the solution of such great practical problems as those presented by cancer and cardiovascular disease.

Indeed, much of Pauling’s work sought to develop the tools necessary to enable chemists to bridge the gap between structure and function.  Pauling spoke somewhat literally of this quest in 1936, in a speech where he compared the tools of the chemist to those of an architect.

The structural chemist of the past and present has been an architect working with materials of whose nature he is largely ignorant – an architect who does not know what an I beam is, but only that it can be used in his construction, and who must proceed to design structure after structure, to find ultimately that certain designs lead to satisfactory results – to a building with rooms adapted to the use of certain visitors, to bridges strong enough to hold their load, and so on. The structural chemist of the future will be able to plan his structures and forecast their properties in the same definite way that the architect and engineer plan the macroscopic, even gargantuan, structures of modern civilization.

In the years just prior to, and at the start of, Pauling’s career, great strides had been made in  molecular structure determinations.

G.N. Lewis, ca. 1930s.

In 1916, for example, Gilbert Newton Lewis developed a theory of molecular diagrams based on valence electrons, now referred to as Lewis-dot structures. The subsequent application of spectroscopic methods to molecular chemistry allowed for more direct quantitative studies of atomic and molecular structure. Later, advancements in quantum mechanics increased chemists’ and physicists’ understanding of the detailed interactions that occur between nuclei and electrons that ultimately determine atomic and molecular structure.  Meanwhile, various valence bond theories had been developed but were not applicable to all matter uniformly.

While these and other contributions were significant, many questions still remained as not all quantitative data aligned with current theories. To provide an explanation for the many apparent holes in understanding, Pauling developed his theory of resonance – an idea which became the central concept of Pauling’s valence theory.

Resonance, or electron exchange, is a property integral to the formation and maintenance of chemical bonds, as it accounts for the formation of hybrid structures that cannot be explained by the classical models of molecular structure alone.

Pauling used his theory of resonance to explain why many molecules can be drawn in various forms according to Lewis’s scheme even though no single structure could be differentiated as the “correct” structure based on energy theories and quantum mechanics.

According to Pauling’s theory, these structures could not be differentiated quantitatively because the electrons exchanged between atoms caused the molecule to resonate between multiple structures. Thus the structure of a molecule is not made up of one single structure, but in some cases, such as in carbon monoxide (CO), the true nature of the molecule resonates between multiple structures. Pauling therein predicted that the CO molecule fluctuates rapidly between multiple conformations thus creating a more stable structure, known as a “resonance hybrid.”

By Pauling’s way of thinking, the theory of resonance explained many of the obvious inconsistencies in the understanding of specific molecules at that time, and he argued that the theory should be applied when predicting new molecular structures and functions.  In our next post, we’ll talk more about the impact of the theory of resonance by examining its application to the study of the enigmatic structure of benzene.