Oganesson

Oganesson is a synthetic, highly radioactive element. Only a few atoms have been made, by fusing calcium and californium nuclei in a particle accelerator, and they decay in less than a millisecond. This leaves too little time to study its chemistry directly. Although it is placed with the noble gases, calculations suggest that oganesson could behave quite differently: it may be a solid at room temperature and more chemically reactive than the lighter noble gases. These are predictions, not measured properties. Oganesson has no practical applications; scientists produce it only for research.