They’re the heaviest members yet of the periodic table, with whopping atomic weights of 289 and 292 atomic mass units respectively. The previous heavyweight winners were copernicium (285) and roentgenium (272).
The two new elements are radioactive and only exist for less than a second before decaying into lighter atoms. Element 116 will quickly decay into 114, and 114 transforms into the slightly lighter copernicium as it sheds its alpha particles.
Evidence for the two elements has been mounting for years. In 1999, for example, Russian physicists bombarded plutonium-244 with calcium-48 to produce a single atom of rapidly decaying 114.
After the discovery of 116 in 2000, a decade of further experimentation and a three-year review process, the new elements were given official status by the International Union of Pure and Applied Chemistry (IUPAC) and the International Union of Pure and Applied Physics on June 1.
“Element 114″ obviously isn’t a very catchy name, especially in a sea of molybdenums and seaborgiums. They have temporary titles — ununquadium and ununhexium — but final names are yet to been decided.
The discoverers at Dubna, the Joint Institute for Nuclear Research, in Russia have proposed the name flerovium for 114, after Soviet element-finder Georgy Flyorov, and moscovium for 116, after Russia’s Moscow region.
The committee also heard arguments for elements 113, 115 and 118. They concluded that the results were encouraging, but don’t quite fulfill the criteria for new elements just yet. The temporarily titled ununtrium, ununpentium and ununoctium, which can weigh as much as 294 atomic mass units, will have to try again in a few years.