einsteinium definition of einsteinium in the Free Online Encyclopedia.

einsteinium (īn`stī'nēəm, īnstī`–) [for Albert Einstein Einstein, Albert (īn`stīn), 1879–1955, American theoretical physicist, known for the formulation of the relativity theory, b.
..... Click the link for more information. ], artificially produced radioactive chemical element; symbol Es; at. no. 99; mass no. of most stable isotope 252; m.p. about 860°C;; b.p. and sp. gr. unknown; valence +2, +3. Einsteinium is a member of Group 3 of the periodic table periodic table, chart of the elements arranged according to the periodic law discovered by Dmitri I. Mendeleev and revised by Henry G. J. Moseley . In the periodic table the elements are arranged in columns and rows according to increasing atomic number (see the
..... Click the link for more information. ; its chemical properties are believed to be similar to those of the other members of the actinide series actinide series, a series of radioactive metallic elements in Group 3 of the periodic table . Members of the series are often called actinides, although actinium (at. no. 89) is not always considered a member of the series.
..... Click the link for more information. . The seventh transuranium element transuranium elements, in chemistry, radioactive elements with atomic numbers greater than that of uranium (at. no. 92). All the transuranium elements of the actinide series were discovered as synthetic radioactive isotopes at the Univ.
..... Click the link for more information. to be discovered, einsteinium was isolated in Dec., 1952, by Albert Ghiorso and his coworkers at the Univ. of California at Berkeley in residue from the first thermonuclear test explosion in the South Pacific. They identified einsteinium-253, which has a half-life half-life, measure of the average lifetime of a radioactive substance (see radioactivity ) or an unstable subatomic particle. One half-life is the time required for one half of any given quantity of the substance to decay.
..... Click the link for more information. of 20.5 days. It was not until 1961 that a weighable quantity (about 0.01 microgram) of the element was separated; it was used to prepare the element mendelevium mendelevium (mĕndəlāv`ēəm), artificially produced radioactive chemical element; symbol Md; at. no. 101; mass no.
..... Click the link for more information. . Weighable quantities of einsteinium have since been prepared by neutron bombardment of plutonium. Seventeen isotopes, all of which are radioactive, are known. Einsteinium-252, the most stable isotope, has a half-life of 1.29 years.

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