Oganesson

The heaviest element known, named after the physicist Yuri Oganessian in his lifetime, and probably not much like a noble gas at all.

At a glance

Symbol: Og
Atomic number: 118
Mass number of its longest-lived isotope: [294]
Group: 18
Period: 7
Family: superheavy element
Electron configuration: [Rn] 5f¹⁴ 6d¹⁰ 7s² 7p⁶ (predicted)
Electronegativity: not measured

On the table

Period 7, group 18. The other superheavy elements are tinted, and every cell opens its own article.

Electrons and bonding

Only a handful of atoms have ever been made, each lasting seconds or less, so its chemistry is predicted from its place in the table rather than measured.

Properties

State at 25 °C: not known
Physical properties: none measured; no more than a few atoms have ever existed at once

Where it is found

Not found in nature. It is made a few atoms at a time in particle accelerators by fusing lighter nuclei, and each atom decays within seconds to hours.

Discovery and name

A team from Dubna and Lawrence Livermore made it by fusing calcium-48 with californium-249, reporting it in 2006; only about five atoms have ever been detected. It was named in 2016 after Yuri Oganessian, who led the Dubna work on superheavy elements.

What it is used for

Research only. Calculations suggest it would be a solid at room temperature and might even be a semiconductor, very different from the noble gases above it.