1.7 micrograms of berkelium; the sample is 100 μm across
24 February 2023
Berkelium, element 97, is a soft, silvery-white, radioactive metal. It does not exist in nature and has no practical uses other than scientific research. Only minute quantities of the element have ever been produced.
The element was first synthesized on 19 December 1949 by Stanley Gerald Thompson, Albert Ghiorso, and Glenn T. Seaborg at the University of California Radiation Laboratory in Berkeley, California (now the Lawrence Berkeley National Laboratory.) Public announcement of the discovery was made on 17 January 1950. As reported by the San Francisco Chronicle:
Dr. Glenn T. Seaborg, 37-year-old professor of chemistry at the university, said it probably would be named Berkelium in honor of the city of Berkeley. The element was discovered December 19 but its announcement withheld pending necessary approval by the Atomic Energy Commission.
(The Chronicle was in possession of the Element 97 story for some days, but because of security considerations elected to hold publication until official announcement yesterday by the University of California.)
Publication of the find in the journal Physical Review followed in March 1950:
It is suggested that element 97 be given the name berkelium (symbol Bk), after the city of Berkeley, in a manner similar to that used in naming its chemical homologue terbium (atomic number 65) whose name was derived from the town of Ytterby, Sweden, where the rare earth minerals were first found.
Some sources say the element is named for the University of California located in Berkeley and not the city itself. That is technically incorrect, but making the distinction is a form of pedantic hair splitting.
Sources:
Oxford English Dictionary, third edition, June 2019, s.v. berkelium, n.
Thompson, S.G., A. Ghiorso, and G.T. Seaborg. “Element 97” (23 January 1950). Physical Review, 77.6, 15 March 1950, 838. Physical Review Journals Archive.
“UC Produces Another New Element.” San Francisco Chronicle, 17 January 1950, 11. Readex: America’s Historical Newspapers.
Photo credit: Oak Ridge National Laboratory, 1971. Wikimedia Commons. Public domain image.