ELEMENTLE

Element 118 · Noble Gas

Oganesson

Period 7 · Group 18

Oganesson is IUPAC's name for the transactinide element with the atomic number 118 and element symbol Og. It is also known as eka-radon or element 118, and on the periodic table of the elements it is a p-block element and the last one of the 7th period. Oganesson is currently the only synthetic member of group 18.

Three reasons Oganesson stands out

  1. 1

    Named after Armenian-Russian nuclear physicist who led the discovery of many elements.

  2. 2

    It is the heaviest element on the entire periodic table and the last element in period 7.

  3. 3

    Despite being classified as a noble gas, it is predicted to be a solid at room temperature and potentially highly reactive.

The table’s heaviest confirmed endpoint

Oganesson completes period seven and honors nuclear physicist Yuri Oganessian. Although placed with the noble gases, theory predicts a highly polarizable element that may be a solid and considerably more reactive than neon or argon. For now, those ideas await experiments on longer-lived isotopes.

Oganesson at a glance
Atomic number / protons118
SymbolOg
Family (Elementle)Noble Gas
Classification (PubChem)Noble gas
Period7
Group18
Atomic mass (u)295.216
Standard stateBulk state not experimentally established
Electron configuration[Rn]7s2 7p6 5f14 6d10 (predicted)
Reported oxidation states+6, +4, +2, +1, 0, -1
Electronegativity (Pauling)Not available
Atomic radius (pm)Not available
First ionization energy (eV)Not available
Electron affinity (eV)Not available
Density (g/cm³)Not available
Melting pointNot available
Boiling pointNot available
Discovery (PubChem)2006

Values are reference data, not a specification for every temperature, pressure, or allotrope. Unknown properties are left unavailable. Superheavy-element predictions remain uncertain.

Sources & further reading

PubChem: Oganesson · Oganesson on Wikipedia

The introduction and original editorial story are adapted from Wikipedia contributors via Periodic-Table-JSON. Element descriptions and their adaptations are available under CC BY-SA 3.0. Numerical attributes use the PubChem periodic-table dataset, retrieved September 22, 2026.