is a chemical element with symbol Cn and atomic number 112. It is an extremely radioactive synthetic element that can only be created in a laboratory. The most stable known isotope, copernicium-285, has a half-life of approximately 29 seconds, but it is possible that this copernicium isotope may have an isomer with an even longer half-life, 8.9 min. It was first created in 1996 by the Gesellschaft für Schwerionenforschung (GSI). It is named after the astronomer Nicolaus Copernicus. In the periodic table of the elements, it is a d-block element, which belongs to transactinide elements. After acknowledging their discovery, the IUPAC asked the discovery team at GSI to suggest a permanent name for ununbium However, it was pointed out that the symbol Cp was previously associated with the name cassiopeium (cassiopium), now known as lutetium (Lu).[17][18] Furthermore, the symbol Cp is also used in organometallic chemistry to denote the cyclopentadienyl ligand. For this reason, the IUPAC disallowed the use of Cp as a future symbol, prompting the GSI team to put forward the symbol Cn as an alternative. On 19 February 2010, the 537th anniversary of Copernicus' birth, IUPAC officially accepted the proposed name and symbol References Hofmann et al. (2000). "New Results on Element 111 and 112". GSI Scientific Report 2000. ^ a b K. Morita (2004). "Decay of an Isotope 277112 produced by 208Pb + 70Zn reaction". Proceedings of the International Symposium. Exotic Nuclei (EXON2004). World Scientific. pp. 188–191. doi:10.1142/9789812701749_0027. ^ Karol, P. J; Nakahara, H; Petley, B. W; Vogt, E (2001). "On the Discovery of the Elements 110–112" (IUPAC Technical Report). Pure Appl. Chem. 73 (6): 959–967. doi:10.1351/pac200173060959. ^ Karol, P. J; Nakahara, H; Petley, B. W; Vogt, E (2003). "On the Claims for Discovery of Elements 110, 111, 112, 114, 116 and 118" (IUPAC Technical Report). Pure Appl. Chem. 75 (10): 1061–1611. doi:10.1351/pac200375101601. ^ R. Dressler; A. Türler (2001). "Evidence for Isomeric States in 261Rf". Annual Report 2001. Paul Scherrer Institute. ^ [1][dead link] ^ Barber, R.C; Gaeggeler, H.W; Karol, P.J; Nakahara, H; Vardaci, E; Vogt, E (2009). "Discovery of the element with atomic number 112" (IUPAC Technical Report). Pure Appl. Chem. 81 (7): 1331. doi:10.1351/PAC-REP-08-03-05. ^ "New Chemical Element In The Periodic Table". www.sciencedaily.com. ^ Barber, Robert C.; Gäggeler, Heinz W.; Karol, Paul J.; Nakahara, Hiromichi; Vardaci, Emanuele; Vogt, Erich (2009). "Discovery of the element with atomic number 112 (IUPAC Technical Report)". Pure and Applied Chemistry 81 (7): 1331. doi:10.1351/PAC-REP-08-03-05. ^ "Element 112 shall be named "copernicium"". www.gsi.de. July 14, 2009. ^ New element named 'copernicium', BBC News, Thu 16 July 2009