premise: Moscovium is a natural element.
hypothesis: Moscovium is a superheavy synthetic element with symbol Mc and atomic number 115 . It was first synthesized in 2003 by a joint team of Russian and American scientists at the Joint Institute for Nuclear Research ( JINR ) in Dubna , Russia . In December 2015 , it was recognized as one of four new elements by the Joint Working Party of international scientific bodies IUPAC and IUPAP . Moscovium is an extremely radioactive element : its most stable known isotope , moscovium-290 , has a half-life of only 0.8 seconds . Moscovium is calculated to have some properties similar to its lighter homologues , nitrogen , phosphorus , arsenic , antimony , and bismuth , and to be a post-transition metal , although it should also show several major differences from them .