/uyn stuy"nee euhm/, n. Chem., Physics.
a transuranic element. Symbol: Es; at. no.: 99.
[1950-55; named after Albert EINSTEIN; see -IUM]

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 (Es), synthetic chemical element of the actinoid series of the periodic table, atomic number 99. Not occurring in nature, einsteinium (as the isotope einsteinium-253), produced by intense neutron irradiation of uranium-238, was identified in December 1952 by Albert Ghiorso and co-workers at Berkeley, Calif., in debris taken from the first thermonuclear or hydrogen-bomb explosion, in the South Pacific (November 1952).

      The material was first collected on filter paper by drone airplanes flying through the radioactive-explosion clouds; later, einsteinium and element 100 (fermium) were positively identified in coral gathered from Enewetak Atoll. Einsteinium metal has not yet been prepared.

      All einsteinium isotopes are radioactive. Mixtures of the isotopes einsteinium-253 (20.5-day half-life), einsteinium-254 (276-day half-life), and einsteinium-255 (38.3-day half-life) can be produced by intensive slow-neutron irradiation of elements of lower atomic number, such as plutonium. Tracer studies indicate that the +3 oxidation state exists in aqueous solution, presumably as the Es3+ ion; there is also some evidence for a +2 state. Einsteinium has chemical properties very similar to those of the other actinoid elements in the tripositive state. Einsteinium-255 and einsteinium-256 eject electrons (beta particles) to form isotopes of fermium (atomic number 100), and einsteinium-253 was used to produce mendelevium (atomic number 101).

atomic number
stablest isotope
oxidation states
+2, +3
electronic config.
[Rn]5f 117s2

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Universalium. 2010.

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  • Einsteinium — (pronEng|aɪnˈstaɪniəm) is a metallic synthetic element. On the periodic table, it is represented by the symbol Es and atomic number 99. It is the seventh transuranic element, and seventh in the series of Actinides. It was named in honor of Albert …   Wikipedia

  • einsteinium — [ ɛnstɛnjɔm ] n. m. • 1955; de Einstein, n. pr. ♦ Chim., phys. Élément atomique, onzième de la série des actinides (Es; no at. 99). L einsteinium est préparé dans un réacteur à haut flux par irradiation du plutonium. ● einsteinium nom masculin… …   Encyclopédie Universelle

  • einsteinium — Symbol: Es Atomic number: 99 Atomic weight: (254) Appearance is unknown, however it is most probably metallic and silver or gray in color. Radioactive metallic transuranic element belonging to the actinoids. Es 254 has the longest half life of… …   Elements of periodic system

  • Einsteinium — discovered in the debris of a 1952 U.S. nuclear test in the Pacific, named 1955 for physicist Albert Einstein (1879 1955) …   Etymology dictionary

  • einsteinium — ☆ einsteinium [īn stīn′ē əm ] n. [ModL, after EINSTEIN2 Albert (in honor of his theoretical studies of mass and energy) + IUM: so named (1955) by A. Ghiorso and co workers, who identified it] a radioactive, metallic chemical element, one of the… …   English World dictionary

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  • Einsteinium — Pour les articles homonymes, voir Einstein (homonymie). Einsteinium Californium ← Ein …   Wikipédia en Français

  • einsteinium — Es Es n. the chemical symbol for {einsteinium}, a transuranic element with atomic number 99. The atomic weight of the longest lived isotope, with a half life of 276 days, is 254. The first isotope discovered, having atomic weight 253 and a half… …   The Collaborative International Dictionary of English

  • Einsteinium — einšteinis statusas T sritis fizika atitikmenys: angl. einsteinium vok. Einsteinium, n rus. эйнштейний, m pranc. einsteinium, m …   Fizikos terminų žodynas

  • einsteinium — einšteinis statusas T sritis fizika atitikmenys: angl. einsteinium vok. Einsteinium, n rus. эйнштейний, m pranc. einsteinium, m …   Fizikos terminų žodynas

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