Oganesson is a synthetic chemical element; it has symbolOg and atomic number 118. It was first synthesized in 2002 at the Joint Institute for Nuclear Research (JINR) in Dubna, near Moscow, Russia, by a joint team of Russian and American scientists. In December 2015, it was recognized as one of four new elements by the Joint Working Party of the international scientific bodies IUPAC and IUPAP. It was formally named on 28 November 2016.[15][16] The name honors the nuclear physicist Yuri Oganessian, who played a leading role in the discovery of the heaviest elements in the periodic table. It is one of only two elements named after a person who was alive at the time of naming, the other being seaborgium, and the only element whose eponym is alive as of 2024[update].[17][a]
Oganesson has the highest atomic number and highest atomic mass of all known elements as of 2024[update]. On the periodic table of the elements it is a p-block element, a member of group 18 and the last member of period 7. Its only known isotope, oganesson-294, is highly radioactive, with a half-life of 0.7 ms and, as of 2020,[update] only five atoms have been successfully produced.[19] This has so far prevented any experimental studies of its chemistry. Because of relativistic effects, theoretical studies predict that it would be a solid at room temperature, and significantly reactive,[3][19] unlike the other members of group 18 (the noble gases).
^ abcHoffman, Darleane C.; Lee, Diana M.; Pershina, Valeria (2006). "Transactinides and the future elements". In Morss; Edelstein, Norman M.; Fuger, Jean (eds.). The Chemistry of the Actinide and Transactinide Elements (3rd ed.). Dordrecht, The Netherlands: Springer Science+Business Media. ISBN978-1-4020-3555-5.
^ abGuo, Yangyang; Pašteka, Lukáš F.; Eliav, Ephraim; Borschevsky, Anastasia (2021). "Chapter 5: Ionization potentials and electron affinity of oganesson with relativistic coupled cluster method". In Musiał, Monika; Hoggan, Philip E. (eds.). Advances in Quantum Chemistry. Vol. 83. pp. 107–123. ISBN978-0-12-823546-1.
^Grosse, A. V. (1965). "Some physical and chemical properties of element 118 (Eka-Em) and element 86 (Em)". Journal of Inorganic and Nuclear Chemistry. 27 (3). Elsevier Science Ltd.: 509–19. doi:10.1016/0022-1902(65)80255-X.
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