einsteinium[īn stīn′ē əm]
a radioactive, metallic chemical element, one of the actinides, discovered in the debris of the first thermonuclear explosion in 1952, but now produced by bombarding plutonium with neutrons: symbol, Es; at. no., 99
Origin of einsteiniumModern Latin after Albert Einstein (in honor of his theoretical studies of mass and energy) + -ium: so named (1955) by A. Ghiorso and co-workers, who identified it
A synthetic transuranic element first produced by neutron irradiation of uranium in a thermonuclear explosion and now usually produced in the laboratory by irradiating plutonium and other elements. The isotopes with the longest half-lives are Es-252 (472 days) and Es-254 (276 days). Atomic number 99; melting point 860°C (estimated); valence 2, 3. See Periodic Table.
Origin of einsteiniumAfter Albert Einstein.