Oganesson

Once the noble gas group was discovered, scientists soon wondered about the possibility of a seventh gas that would fill in gaps on the periodic table. Even in 1895, the year after argon was discovered, Danish chemist Hans Peter Jørgen Julius Thomsen hypothesized that a group of unreactive gases (now known as the noble gases) would end with an element at an atomic weight of 292—a near-accurate prediction of oganesson-294, the first and only isotope of oganesson.

Though many scientists claimed possible discoveries of the hypothesized element over the years, it wasn’t until 2015 that oganesson was discovered by a group of scientists from the Joint Institute for Nuclear Research (JINR) in Russia and the Lawrence Livermore National Laboratory in California.

Oganesson is highly radioactive and has an extremely short half-life (0.69 milliseconds!). Not much else is known about this gas, however, scientists can make educated guesses, or hypotheses, based on the characteristics of its neighbors in the periodic table. For example, like other noble gases, it is predicted to be a diatomic molecule, meaning it only pairs with itself.

Oganesson has no uses beyond scientific research.

Oganesson-294 is the only isotope of oganesson. It is extremely unstable with a half-life of 700 microseconds!

Oganesson is not found in nature, so we can only study it in a laboratory setting. Like any synthetic element, making oganesson is tricky. Using a heavy ion accelerator, a beam of energy launches calcium-48 into a target made of californium-249, californium-250, and californium-251. Scientists must then find the oganesson isotopes in the fallout of the collision.