(redirected from Element 99)
Also found in: Thesaurus, Medical, Encyclopedia.


n. Symbol Es
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.

[After Albert Einstein.]


(Elements & Compounds) a metallic transuranic element artificially produced from plutonium. Symbol: Es; atomic no: 99; half-life of most stable isotope, 252Es: 276 days
[C20: New Latin, named after Albert Einstein]


(aɪnˈstaɪ ni əm)

a transuranic element. Symbol: Es; at. no.: 99.
[1950–55; after Albert Einstein; see -ium2]


Symbol Es A synthetic, radioactive metallic element of the actinide series that is usually produced by bombarding plutonium or another element with neutrons. The most stable isotope of einsteinium has a half-life of 1.3 years. Atomic number 99. See Periodic Table.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.einsteinium - a radioactive transuranic element produced by bombarding plutonium with neutronseinsteinium - a radioactive transuranic element produced by bombarding plutonium with neutrons
metal, metallic element - any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc.