darmstadtium, artificially produced radioactive chemical element; symbol Ds; at. no. 110; mass number of most stable isotope 281; m.p., b.p., sp. gr., and valence unknown. Situated in Group 10 of the periodic table, it is expected to have properties similar to those of platinum.

In 1994 an international research team led by Peter Armbruster and Sigurd Hofmann at the Institute for Heavy Ion Research at Darmstadt, Germany, bombarded lead-208 atoms with nickel-62 ions. In a two-week experiment, four atoms were unambiguously identified as an isotope of element 110 with mass number 269 and a half-life of 0.17 msec. In a separate experiment, again using the lead-208 target but bombarding it with nickel-64 ions, the same team created nine atoms of an element 110 isotope with mass number 271 and a half-life of 1.4 msec. Six isotopes have been synthesized and unambiguously identified. The Germans suggested the name darmstadtium to honor Darmstadt, where their institute is located. This name was recognized internationally in 2003. The most stable isotope, darmstadtium-281, has a half-life of approximately 11 sec.

See also synthetic elements; transactinide elements; transuranium elements.

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