Oganesson (Og)

Oganesson (symbol Og) is the chemical element with atomic number 118: a superheavy element whose properties are still unknown, radioactive, made artificially, with an atomic mass of 294 u. Discovered in 2002 (Dubna and Livermore laboratories).

Oganesson closes the seventh row of the periodic table. It is named after Yuri Oganessian, a Russian-Armenian physicist from Dubna, making it the second element named after a living person, after seaborgium. Only about five atoms have been identified, each lasting less than a millisecond. Although it sits in the noble gas column, it would most likely be solid at room temperature.

Key facts

Atomic number: 118
Symbol: Og
French name: Oganesson
Atomic mass: 294 u
Molar mass: [294] g/mol
Family: Unknown properties
Position: period 7, group 18, p-block
State at 0 °C: Unknown
First ionization energy: 860 kJ/mol
Electron configuration: [Rn] 5f¹⁴ 6d¹⁰ 7s² 7p⁶
Radioactive: yes
Discovery: 2002, Dubna and Livermore laboratories

Origin of the name

In honor of the Russian physicist Yuri Oganessian.

What does oganesson look like?

Never observed. Calculations suggest a solid, perhaps a semiconductor, because of relativistic effects that upend the behavior of its electrons.

Where is oganesson found?

Absent from nature.

How is oganesson produced?

Dubna, in collaboration with Livermore, bombarded a californium-249 target with calcium-48 ions for months. It takes billions of billions of ions to obtain a single atom of oganesson-294, whose half-life is about 0.7 milliseconds.

Top producers

Russia (Dubna)
United States (Livermore, collaborator)

What is oganesson used for?

Basic research only

In everyday life

None — it exists only for moments in the lab

Role in living things

No biological role.

Hazards of oganesson

Radioactive, but produced atom by atom: no practical danger.

Cosmic origin

Human-made: Does not exist (or barely) in nature: synthesized in a reactor or accelerator.

History of oganesson

Berkeley had announced element 118 in 1999, before withdrawing the claim over fraud. The first genuine atom was observed in Dubna in 2002, followed by others in 2005; the discovery was published in 2006. IUPAC recognized it at the end of 2015, and the name oganesson became official in 2016.

Did you know?

With 118 protons, it is the heaviest atom ever made; scientists are now trying to create elements 119 and 120, notably at RIKEN and Dubna.
Its “-on” ending echoes that of the noble gases (neon, argon, krypton, xenon, radon).
Yuri Oganessian lived to see “his” element enter the periodic table.

Isotopes of oganesson

Only one known isotope, oganesson-294, observed as just five atoms. It is the heaviest nucleus ever created.

oganesson-294: radioactive, half-life 700 µs. The element's first and only synthesized isotope, in 2002 in Dubna.

Related elements

Same family (unknown properties): Meitnerium (Mt), Darmstadtium (Ds), Roentgenium (Rg), Copernicium (Cn), Nihonium (Nh), Flerovium (Fl), Moscovium (Mc), Livermorium (Lv), Tennessine (Ts).

Same column (group 18): Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), Radon (Rn).