Glenn Theodore Seaborg was born in Ishpeming, Michigan, on April 19, 1912, the son of Herman Theodore (Ted) and Selma Olivia Erickson Seaborg. He had one sister, Jeanette, who was two years younger. His family spoke Swedish at home. When Glenn Seaborg was a boy, the family moved to Los Angeles County, California, settling in a subdivision called Home Gardens, later annexed to the City of South Gate, California. About this time he changed the spelling of his first name from Glen to Glenn.

Seaborg graduated from Jordan in 1929 at the top of his class and received a Bachelor of Arts (AB) degree in chemistry at the University of California, Los Angeles, in 1933. He worked his way through school as a stevedore and a laboratory assistant at Firestone. Seaborg received his PhD in chemistry at the University of California, Berkeley, in 1937 with a doctoral thesis on the “Interaction of Fast Neutrons with Lead”, in which he coined the term “nuclear spallation”.

Seaborg remained at the University of California, Berkeley, for post-doctoral research. He followed Frederick Soddy’s work investigating isotopes and contributed to the discovery of more than 100 isotopes of elements. Using one of Lawrence’s advanced cyclotrons, John Livingood, Fred Fairbrother, and Seaborg created a new isotope of iron, iron-59 in 1937. Iron-59 was useful in the studies of the hemoglobin in human blood. In 1938, Livingood and Seaborg collaborated (as they did for five years) to create an important isotope of iodine, iodine-131, which is still used to treat thyroid disease. (Many years later, it was credited with prolonging the life of Seaborg’s mother.) As a result of these and other contributions, Seaborg is regarded as a pioneer in nuclear medicine and is one of its most prolific discoverers of isotopes.

In 1939 he became an instructor in chemistry at Berkeley, was promoted to assistant professor in 1941 and professor in 1945. University of California, Berkeley, physicist Edwin McMillan led a team that discovered element 93, which he named neptunium in 1940. In November, he was persuaded to leave Berkeley temporarily to assist with urgent research in radar technology. Since Seaborg and his colleagues had perfected McMillan’s oxidation-reduction technique for isolating neptunium, he asked McMillan for permission to continue the research and search for element 94. McMillan agreed to the collaboration. Seaborg first reported alpha decay proportionate to only a fraction of the element 93 under observation. The first hypothesis for this alpha particle accumulation was contamination by uranium, which produces alpha-decay particles; analysis of alpha-decay particles ruled this out. Seaborg then postulated that a distinct alpha-producing element was being formed from element 93.

In February 1941, Seaborg and his collaborators produced plutonium-239 through the bombardment of uranium. In their experiments bombarding uranium with deuterons, they observed the creation of neptunium, element 93. But it then underwent beta-decay, forming a new element, plutonium, with 94 protons. Plutonium is fairly stable, but undergoes alpha-decay, which explained the presence of alpha particles coming from neptunium. Thus, on March 28, 1941, Seaborg, physicist Emilio Segrè and Berkeley chemist Joseph W. Kennedy were able to show that plutonium (then known only as element 94) was fissile, an important distinction that was crucial to the decisions made in directing Manhattan Project research. In 1966, Room 307 of Gilman Hall on the campus at the Berkeley, where Seaborg did his work, was declared a U.S. National Historic Landmark.

On April 19, 1942, Seaborg reached Chicago and joined the chemistry group at the Metallurgical Laboratory of the Manhattan Project at the University of Chicago, where Enrico Fermi and his group would later convert uranium-238 to plutonium-239 in a controlled nuclear chain reaction. Seaborg’s role was to figure out how to extract the tiny bit of plutonium from the mass of uranium. Plutonium-239 was isolated in visible amounts using a transmutation reaction on August 20, 1942, and weighed on September 10, 1942, in Seaborg’s Chicago laboratory. He was responsible for the multi-stage chemical process that separated, concentrated and isolated plutonium. This process was further developed at the Clinton Engineering Works in Oak Ridge, Tennessee, and then entered full-scale production at the Hanford Engineer Works, in Richland, Washington.

In 1942, Seaborg married Helen Griggs, the secretary of physicist Ernest Lawrence. Under wartime pressure, Seaborg had moved to Chicago while engaged to Griggs. When Seaborg returned to accompany Griggs for the journey back to Chicago, friends expected them to marry in Chicago. But, eager to be married, Seaborg and Griggs impulsively got off the train in the town of Caliente, Nevada, for what they thought would be a quick wedding. When they asked for City Hall, they found Caliente had none—they would have to travel 25 miles (40 km) north to Pioche, the county seat. With no car, this was no easy feat, but one of Caliente’s newest deputy sheriffs turned out to be a recent graduate of the Cal Berkeley chemistry department and was more than happy to do a favor for Seaborg. The deputy sheriff arranged for the wedding couple to ride up and back to Pioche in a mail truck. The witnesses at the Seaborg wedding were a clerk and a janitor. Glenn Seaborg and Helen Griggs Seaborg had seven children, of whom the first, Peter Glenn Seaborg, died in 1997 (his twin Paulette having died in infancy). The others were Lynne Seaborg Cobb, David Seaborg, Steve Seaborg, Eric Seaborg, and Dianne Seaborg.

After the conclusion of World War II and the Manhattan Project, Seaborg was eager to return to academic life and university research free from the restrictions of wartime secrecy. In 1946, he added to his responsibilities as a professor by heading the nuclear chemistry research at the Lawrence Radiation Laboratory operated by the University of California on behalf of the United States Atomic Energy Commission. Seaborg was named one of the “Ten Outstanding Young Men in America” by the U.S. Junior Chamber of Commerce in 1947 (along with Richard Nixon and others). Seaborg was elected a Member of the National Academy of Sciences in 1948. From 1954 to 1961 he served as associate director of the radiation laboratory. He was appointed by President Truman to serve as a member of the General Advisory Committee of the Atomic Energy Commission, an assignment he retained until 1960.

In addition to plutonium, he is credited as a lead discoverer of americium, curium, and berkelium, and as a co-discoverer of californium, einsteinium, fermium, mendelevium, nobelium and seaborgium. He shared the Nobel Prize in Chemistry in 1951 with Edwin McMillan for “their discoveries in the chemistry of the first transuranium elements.”

Seaborg served as chancellor at the University of California, Berkeley, from 1958 to 1961. His term coincided with a relaxation of McCarthy-era restrictions on students’ freedom of expression that had begun under his predecessor, Clark Kerr. In October 1958, Seaborg announced that the University had relaxed its prior prohibitions on political activity on a trial basis, and the ban on communists speaking on campus was lifted. This paved the way for the Free Speech Movement of 1964–65.

Seaborg was an enthusiastic supporter of Cal’s sports teams. San Francisco columnist Herb Caen was fond of pointing out that Seaborg’s surname is an anagram of “Go Bears”, a popular cheer at UC Berkeley. Seaborg was proud of the fact that the Cal Bears won their first and only National Collegiate Athletic Association (NCAA) basketball championship in 1959, while he was chancellor. The football team also won the conference title and played in the Rose Bowl that year. He served on the Faculty Athletic Committee for several years and was the co-author of a book, Roses from the Ashes: Breakup and Rebirth in Pacific Coast Intercollegiate Athletics (2000), concerning the Pacific Coast Conference recruiting scandal, and the founding of what is now the Pac-12, in which he played a role in restoring confidence in the integrity of collegiate sports.

Seaborg served on the President’s Science Advisory Committee (PSAC) during the Eisenhower administration. PSAC produced a report on “Scientific Progress, the Universities, and the Federal Government”, also known as the “Seaborg Report”, in November 1960, that urged greater federal funding of science. In 1959, he helped found the Berkeley Space Sciences Laboratory with Clark Kerr.

After appointment by President John F. Kennedy and confirmation by the United States Senate, Seaborg was chairman of the Atomic Energy Commission (AEC) from 1961 to 1971. His pending appointment by President-elect Kennedy was nearly derailed in late 1960 when members of the Kennedy transition team learned that Seaborg had been listed in a U.S. News & World Report article as a member of “Nixon’s Idea Men”. Seaborg said that as a lifetime Democrat he was baffled when the article appeared associating him with outgoing Vice President Richard Nixon, a Republican whom Seaborg considered a casual acquaintance.

Seaborg was an avid hiker. Upon becoming Chairman of the Atomic Energy Commission in 1961, he commenced taking daily hikes through a trail that he blazed at the headquarters site in Germantown, Maryland. He frequently invited colleagues and visitors to accompany him, and the trail became known as the “Glenn Seaborg Trail.” He and his wife Helen are credited with blazing a 12-mile (19 km) trail in the East Bay area near their home in Lafayette, California. This trail has since become a part of the American Hiking Association’s cross-country network of trails. Seaborg and his wife walked the trail network from Contra Costa County all the way to the California–Nevada border.

The American Chemical Society-Chicago Section honored him with the Willard Gibbs Award in 1966. The American Academy of Achievement presented Seaborg with the Golden Plate Award in 1972. The element seaborgium was named after Seaborg by Albert Ghiorso, E. Kenneth Hulet, and others, who also credited Seaborg as a co-discoverer. It was named while Seaborg was still alive, which proved controversial. He influenced the naming of so many elements that with the announcement of seaborgium, it was noted in Discover magazine’s review of the year in science that he could receive a letter addressed in chemical elements: seaborgium, lawrencium (for the Lawrence Berkeley Laboratory where he worked), berkelium, californium, americium. Seaborgium is the first element ever to have been officially named after a living person. The second element to be so named is oganesson, in 2016, after Yuri Oganessian.

Seaborg enjoyed a close relationship with President Lyndon Johnson and influenced the administration to pursue the Nuclear Non-Proliferation Treaty. Seaborg was called to the White House in the first week of the Nixon Administration in January 1969 to advise President Richard Nixon on his first diplomatic crisis involving the Soviets and nuclear testing. He clashed with Nixon presidential adviser John Ehrlichman over the treatment of a Jewish scientist, Zalman Shapiro, whom the Nixon administration suspected of leaking nuclear secrets to Israel.

Following his service as Chairman of the Atomic Energy Commission, Seaborg returned to UC Berkeley where he was awarded the position of University Professor. At the time, there had been fewer University Professors at UC Berkeley than Nobel Prize winners. He also served as Chairman of the Lawrence Hall of Science where he became the principal investigator for Great Explorations in Math and Science (GEMS) working with director Jacqueline Barber. Seaborg served as chancellor at the University of California, Berkeley, from 1958 to 1961, and served as President of the American Association for the Advancement of Science in 1972 and as President of the American Chemical Society in 1976.

Seaborg was elected a foreign member of the Royal Swedish Academy of Sciences in 1972 and a Foreign Member of the Royal Society (ForMemRS) of London in 1985. He was honored as Swedish-American of the Year in 1962 by the Vasa Order of America. In 1991, the organization named “Local Lodge Glenn T. Seaborg No. 719” in his honor during the Seaborg Honors ceremony at which he appeared. This lodge maintains a scholarship fund in his name, as does the unrelated Swedish-American Club of Los Angeles.

In 1980, he transmuted several thousand atoms of bismuth into gold at the Lawrence Berkeley Laboratory. His experimental technique, using nuclear physics, was able to remove protons and neutrons from the bismuth atoms. Seaborg’s technique would have been far too expensive to enable routine manufacturing of gold, but his work was close to the mythical Philosopher’s Stone.

In 1981, Seaborg became a founding member of the World Cultural Council.

In 1983, President Ronald Reagan appointed Seaborg to serve on the National Commission on Excellence in Education. The commission produced a report “A Nation at Risk: The Imperative for Educational Reform”, which focused national attention on education as a national issue germane to the federal government. In 2008, Margaret Spellings wrote that

Seaborg kept a daily journal from 1927 until he suffered a stroke in 1998. As a youth, Seaborg was both a devoted sports fan and an avid movie buff. His mother encouraged him to become a bookkeeper as she felt his literary interests were impractical. He did not take an interest in science until his junior year when he was inspired by Dwight Logan Reid, a chemistry and physics teacher at David Starr Jordan High School in Watts.

On August 24, 1998, while in Boston to attend a meeting by the American Chemical Society, Seaborg suffered a stroke, which led to his death six months later on February 25, 1999, at his home in Lafayette.

During his lifetime, Seaborg is said to have been the author or co-author of numerous books and 500 scientific journal articles, many of them brief reports on fast-breaking discoveries in nuclear science while other subjects, most notably the actinide concept, represented major theoretical contributions in the history of science. He held more than 40 patents—among them the only patents ever issued for chemical elements, americium and curium, and received more than 50 doctorates and honorary degrees in his lifetime. At one time, he was listed in the Guinness Book of World Records as having the longest entry in Marquis Who’s Who in America. In February 2005, he was posthumously inducted into the National Inventors Hall of Fame. In April 2011 the executive council of the Committee for Skeptical Inquiry (CSI) selected Seaborg for inclusion in CSI’s Pantheon of Skeptics. The Pantheon of Skeptics was created by CSI to remember the legacy of deceased fellows of CSI and their contributions to the cause of scientific skepticism. His papers are in the Library of Congress.