hassium

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hassium

(hăs`ēəm, häs`–), artificially produced radioactive chemical element; symbol Hs; at. no. 108; mass number of most stable isotope 277; m.p., b.p., sp. gr., and valence unknown. Situated in Group 8 of the periodic tableperiodic 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 table entitled
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, it is expected to have properties similar to those of osmiumosmium
, metallic chemical element; symbol Os; at. no. 76; at. wt. 190.23; m.p. 3,045±30°C;; b.p. 5,027±100°C;; sp. gr. 22.57 at 20°C;; valence usually +0 to +8.
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In 1984 a German research team led by P. Armbruster and G. Münzenberg at the Institute for Heavy Ion Research at Darmstadt bombarded lead-208 atoms with iron-58 ions. In 10 days of bombardment, they successfully produced three atoms of an isotope of element 108 with mass number 265 and a half-lifehalf-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.
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 of only 2 msec. They suggested that the new element be named hassium, which is derived from the Latin name for the German state of HesseHesse
, Ger. Hessen, state (1994 pop. 5,800,000), 8,150 sq mi (24,604 sq km), central Germany. Wiesbaden is the capital. It is bounded by Baden-Württemberg and Bavaria in the south, Rhineland-Palatinate in the west, North Rhine–Westphalia and Lower Saxony in
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, where the institute is located. In 1994 a committee of the International Union of Pure and Applied Chemistry (IUPAC), convened to resolve naming disputes for the transactinide elementstransactinide elements
, in chemistry, elements with atomic numbers greater than that of lawrencium (at. no. 103), the last member of the actinide series. See transuranium elements.
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, recommended that element 108 be named hahnium. The name hassium was adopted internationally, however, in 1997. The most stable isotope of hassium, hassium-277, has a half-life of approximately 11 min.

See also synthetic elementssynthetic elements,
in chemistry, radioactive elements that were not discovered occurring in nature but as artificially produced isotopes. They are technetium (at. no. 43), which was the first element to be synthesized, promethium (at. no. 61), astatine (at. no.
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; transuranium elementstransuranium 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.
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hassium

[′hä·sē·əm]
(chemistry)
A chemical element, symbolized Hs, atomic number 108, a synthetic element; the sixteenth transuranium element.

hassium

a synthetic element produced in small quantities by high-energy ion bombardment. Symbol: Hs; atomic no. 108