Glenn T. Seaborg, in full Glenn Theodore Seaborg, (born April 19, 1912, Ishpeming, Mich., U.S.—died Feb. 25, 1999, Lafayette, Calif.), American nuclear chemist best known for his work on isolating and identifying transuranium elements (those heavier than uranium). He shared the 1951 Nobel Prize for Chemistry with Edwin Mattison McMillan for their independent discoveries of transuranium elements. Seaborgium was named in his honour, making him the only person for whom a chemical element was named during his lifetime.

Seaborg learned Swedish from his immigrant mother before he learned English. When he was 10, his family moved to a suburb of Los Angeles. He received a bachelor’s degree (1934) from the University of California, Los Angeles, and a doctorate (1937) from the University of California, Berkeley. He stayed on at Berkeley as the personal laboratory assistant of Gilbert N. Lewis from 1937 to 1939. He also collaborated at Berkeley with physicist Jack Livingood to isolate a number of radioactive isotopes, including iodine-131, which later saved his mother’s life and is now used for the diagnosis and treatment of thyroid disorders. At Berkeley he was, successively, research associate, instructor, and assistant professor (1937–45), becoming professor of chemistry in 1946. He served as Berkeley’s chancellor from 1958 to 1961.

Seaborg, together with Arthur C. Wahl and Joseph W. Kennedy, produced and identified the second known transuranium element, plutonium (atomic number 94), on Feb. 23, 1941, in Room 307 of Gilman Hall, which is now a National Historic Landmark. (McMillan had discovered the first transuranium element, neptunium [atomic number 93], the previous year at Berkeley.) In addition to plutonium, best known for its use as a fuel in certain types of nuclear reactors and as an ingredient in some nuclear weapons, Seaborg and his coworkers discovered nine more new elements (atomic numbers 95–102 and 106) between 1941 and 1955.

The early studies of plutonium were carried out on a tracer scale with amounts too small to be weighed. The first visible amount of plutonium (about a millionth of a gram of plutonium fluoride) was isolated by Seaborg, Burris B. Cunningham, and Louis B. Werner on Aug. 20, 1942. During World War II, which Seaborg spent as a section chief at the University of Chicago Metallurgical Laboratory, the first industrial production of plutonium was undertaken in newly devised uranium reactors, and he had the primary responsibility for isolating plutonium from the reaction products and scaling up its extraction from ultramicroscopic laboratory amounts to a full-scale plant (the Hanford Engineering Works in Washington) by what he called “surely the greatest scale-up factor [10 billion] ever attempted.”

Get exclusive access to content from our 1768 First Edition with your subscription. Subscribe today

The other new elements discovered by Seaborg were americium (95), curium (96), berkelium (97), californium (98), einsteinium (99), fermium (100), mendelevium (101), nobelium (102), and seaborgium (106). By chance, Seaborg first announced the discovery of elements 95 and 96 in response to a question on a Nov. 11, 1945, Quiz Kids radio program. The prediction of the chemical properties, method of isolation, and placement of these and many heavier elements in the periodic table of the elements was helped greatly by an important organizing principle enunciated by Seaborg in 1944 and known as the actinide concept. This was one of the most significant changes in the periodic table since Russian chemist Dmitry Mendeleyev’s original conception in 1869. Seaborg recognized that the 14 elements heavier than actinium (89) are closely related to it and belong to a separate group in the periodic table, the actinide elements (now actinoid elements), analogous to the 14 elements heavier than lanthanum (57), the lanthanoids or rare earth elements.

Seaborg returned to Berkeley in 1946, where he was involved in the discovery of berkelium and succeeding elements. He was the first scientist named chairman of the Atomic Energy Commission (1961–71), and the U.S. nuclear-weapons and power industry developed rapidly during his tenure. Beginning in 1959, he was a leader in the movement to improve high-school and college chemistry curricula in the United States and abroad. He was a member of the National Commission on Excellence in Education that produced the 1983 report “A Nation at Risk: The Imperative for Educational Reform.”

A lifelong aficionado of athletics, Seaborg in 1958 helped establish the Athletic Association of Western Universities (now the Pacific-12 Conference). His activities and honours—governmental, academic, and educational—were so multifaceted and extensive that he was cited in the Guinness Book of World Records as having the longest entry in Who’s Who in America.

As an adviser to 10 U.S. presidents, from Franklin D. Roosevelt to George H.W. Bush, Seaborg visited more than 60 countries to promote international scientific cooperation and nuclear arms control treaties. Although he was actively involved in the development of the atomic bomb, he was one of the six signatories of the Franck Report (1945), which urged that the bomb be demonstrated to the Japanese instead of being used against a civilian population. He considered control of nuclear weapons the most crucial problem facing humanity, and he laid the groundwork for the 1968 Treaty on the Non-proliferation of Nuclear Weapons, which he considered “perhaps the most important step in arms limitation since the advent of the nuclear age.”

In 1971 Seaborg returned to the University of California, Berkeley, where he served as university professor, associate director-at-large of the Lawrence Berkeley Laboratory, and chairman of the Lawrence Hall of Science (1984–99). He died from complications of a stroke that he suffered in Boston in August 1998 at a national meeting of the American Chemical Society, the world’s largest organization devoted to a single science, in which he was very active, serving as president in 1976.

Seaborg was the author of The Transuranium Elements (1958), Man-Made Transuranium Elements (1963), Nuclear Milestones: A Collection of Speeches by Glenn T. Seaborg (1972), and A Chemist in the White House: From the Manhattan Project to the End of the Cold War (1998), which chronicles scientific and political issues through his decades of public service, including excerpts from journals and policy-making letters. Shortly after winning the Nobel Prize, Seaborg wrote a number of entries for the 14th edition of the Encyclopædia Britannica, among them the article on plutonium for the 1953 printing.