Overview

Berkelium was first synthesised in December 1949 at the University of California, Berkeley, by Stanley Thompson, Albert Ghiorso and Glenn Seaborg, by bombarding americium with alpha particles. It was named after the city of Berkeley, home of the laboratory where so many of the transuranium elements were made. Berkelium is a silvery, radioactive metal, produced only in minute quantities and used chiefly as a target for making still heavier elements. Made in only milligram amounts in the world's most powerful reactors, berkelium has no use outside research, but it is a precious target material: bombarded with calcium ions it yielded tennessine, element 117, one of the last gaps in the periodic table to be filled.

A single gram of berkelium is estimated to cost on the order of hundreds of millions of dollars to produce, since making even the milligram-scale quantities used to synthesise tennessine required Oak Ridge National Laboratory's High Flux Isotope Reactor to irradiate target material continuously for many months, followed by a lengthy chemical purification process, making the 2009 batch used for that experiment one of the most expensive small quantities of matter ever deliberately manufactured.