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.]
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