The element with an atomic number of 118 is Oganesson (Og). Oganesson is a synthetic element that was first synthesized in 2002 by a team of Russian and American scientists. It is a member of the noble gases group on the periodic table and is currently the heaviest known element. Due to its high atomic number and instability, oganesson is highly reactive and has a very short half-life, making it difficult to study.