1. A synthetic chemical element with atomic number 118, belonging to the halogen group; the heaviest known element.
Usage: chemistry; symbol: Og; Named after Russian nuclear physicist Yuri Oganessian

Examples

• Oganesson was officially named and added to the periodic table in 2016.
• The element oganesson is extremely rare and exists only in laboratory settings.
• Scientists created oganesson by colliding calcium-48 ions with californium-249 targets.
• Oganesson has an atomic number of 118, making it the last element on the periodic table.
• The properties of oganesson are still being studied by nuclear chemists.