oganesson

Meanings

1. The chemical element (symbol Og) with atomic number 118. It is the heaviest known element. Highly radioactive, it does not occur naturally. Originally expected to be a noble gas, it is now predicted to be a reactive metallic solid, and a semiconductor or a post-transition metal.

Etymology

From Oganessian + -on. Promulgated in June 2016 by IUPAC based on recommendations of the Joint Institute for Nuclear Research and Lawrence Livermore National Laboratory to honor Russian-Armenian physicist Yuri Oganessian (born 1933) who researched superheavy elements. Suffix -on, rather than -ium, is because it is a noble gas (like neon or argon).