premise: Moscovium is a synthetic 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 . Moscovium is an extremely radioactive element : its most stable known isotope , moscovium-290 , has a half-life of only 0.8 seconds .