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Ununhexium, artificially produced radioactive chemical element ; symbol Uuh; at. no. 116; mass number of most stable isotope 292; m.p., b.p., sp. gr., and valence unknown. Situated in Group 16 of the periodic table, it is expected to have properties similar to those of polonium and tellurium . In 1999 a research team at the Lawrence Berkeley National Laboratory in Calif. bombarded lead-208 atoms with high-energy krypton-86 ions to create, apparently, ununoctium (element 118) atoms. The Uuo-293 isotope that they synthesized emitted an alpha particle to decay into Uuh-289, which has a life-life of about 0.6 millisecond, which then emitted an alpha particle to decay into ununquadium (element 114). Although the Berkeley laboratory retracted its claim for creating ununoctium in 2001, other research teams have since created ununhexium directly. No name has yet been adopted for element 116, which is therefore called ununhexium, from the Latin roots un for one and hex for six, under a con...

. Element 116, also called ununhexium (Uuh), chemical element with atomic number 116. Each ununhexium atom has a nucleus, or inner core, containing particles called neutrons and protons (see Atom ). The number of protons in the nucleus of an atom determines the element’s atomic number. The nucleus of an atom of ununhexium, therefore, contains 116 protons. Ununhexium has never been found in nature but can be produced in the laboratory by nuclear fusion (a process in which a chemical element with larger atoms is produced by fusing together two smaller atoms of other elements). Scientists at the Joint Institute for Nuclear Research in Dubna, Russia, created the first atom of ununhexium in mid-2001. They produced ununhexium by using a machine called a particle accelerator to accelerate calcium atoms to a very high velocity and then smashing them into atoms of the element curium. In a very small percentage of these collisions, an atom of calcium combines with an atom of curium to form a...