American nuclear chemist · 1912–1999
Glenn T. Seaborg
Glenn Seaborg took part in the discovery of plutonium and nine other elements, and then redrew the bottom of the periodic table to make room for them. Element 106, seaborgium, was named after him in his lifetime, an honour very few scientists have received.
- Elements credited
- 6
- Discoveries
- 1940–1955
- Co-discoverers
- 10
- Where
- United States
Discovery timeline
1940 · United States
Plutonium is a radioactive metal used in nuclear weapons and reactors. Plutonium-238 powers deep-space probes.
1944 · United States
Americium is a radioactive, silvery metal found in nearly every household smoke detector.
1944 · United States
Curium is a hard, dense, radioactive metal that glows red-purple in the dark.
1949 · United States
Berkelium is a radioactive metal made only in tiny amounts in high-flux nuclear reactors.
1950 · United States
Californium is a radioactive metal and an intense neutron source. It is one of the most expensive materials ever made.
1955 · United States
Mendelevium is a synthetic radioactive element named after the father of the periodic table.
The discoveries
In late 1940 and early 1941, working with Edwin McMillan’s neptunium research at Berkeley, Seaborg, Arthur Wahl and Joseph Kennedy bombarded uranium with deuterons and identified element 94, plutonium. Within months they showed that plutonium-239 splits under slow neutrons, which made it a candidate for nuclear weapons and reactors.
During the Manhattan Project Seaborg led the chemistry that separated plutonium on an industrial scale. His group also identified americium and curium in 1944. Both resisted separation because they behaved so similarly, and that problem gave him his most important idea.
Seaborg proposed that the heaviest elements form a new series, the actinides, filling the 5f orbitals just as the lanthanides fill 4f. Colleagues warned that publishing such a radical change would ruin his reputation. He published anyway, the prediction guided the search for berkelium, californium and mendelevium, and the actinide row has sat under the main table ever since.
Life and career
Seaborg was born in Ishpeming, Michigan, to Swedish immigrant parents, and moved to Los Angeles as a child. He studied chemistry at UCLA and earned his PhD at Berkeley in 1937.
He shared the 1951 Nobel Prize in Chemistry with McMillan, served as chancellor of the University of California, Berkeley, and chaired the US Atomic Energy Commission from 1961 to 1971 under three presidents. He also championed science education and served on the commission that produced the 1983 report A Nation at Risk.
Also known for
- The actinide concept, which reshaped the periodic table
- 1951 Nobel Prize in Chemistry
- Chair of the US Atomic Energy Commission, 1961–1971
- First person to have an element named after them while still alive