Ununoctium Element Facts

Ununoctium Radioactive

A combination of experiments and computer simulations enable predictions to be made of deformations and shapes of the heaviest elements in and beyond the current periodic table. Image Ref. (3)


Data Zone

Classification: Ununoctium is a noble gas
(or a noble solid?) and a nonmetal
Atomic weight: (294), no stable isotopes
State: gas (presumed)
Melting point:
Boiling point:
Electrons: 118
Protons: 118
Neutrons in most abundant isotope: 176
Electron shells: 2, 8, 18, 32, 32, 18, 8
Electron configuration: [Rn] 5f14 6d10 7s2 7p6 (presumed)
Show more, including: Heats, Energies, Oxidation, Reactions, Compounds, Radii, Conductivities
Specific heat capacity
Heat of fusion
Heat of atomization
Heat of vaporization
1st ionization energy
2nd ionization energy
3rd ionization energy
Electron affinity
Minimum oxidation number
Min. common oxidation no.
Maximum oxidation number
Max. common oxidation no.
Electronegativity (Pauling Scale)
Polarizability volume
Reaction with air
Reaction with 15 M HNO3
Reaction with 6 M HCl
Reaction with 6 M NaOH
Atomic radius
Ionic radius (1+ ion)
Ionic radius (2+ ion)
Ionic radius (3+ ion)
Ionic radius (1- ion)
Ionic radius (2- ion)
Ionic radius (3- ion)
Thermal conductivity
Electrical conductivity
Freezing/Melting point:

The cyclotron at Dubna

The heavy ion cyclotron U-400 in Dubna, where ununoctium may have been synthesized.

Discovery of Ununoctium

Dr. Doug Stewart

Research scientists at the Joint Institute for Nuclear Research in Dubna, Russia and the Lawrence Livermore National Laboratory (LLNL), California believed they had made element 118, ununoctium, in 2002.

The reaction was a fusion of element 20 with element 98: calcium-48 with californium-249.

Calcium ions were formed into a beam in a cyclotron (a particle accelerator) and fired at a target layer of californium oxide deposited on titanium foil.

Bombardment lasted 2300 hours, accumulating a total dose of 2.5 x 1019 calcium ions.
Two atoms of ununoctium-294, which existed for 2.55 ms and 3.16 ms, may have been produced in March 2002. (1)

In 2011, The International Union of Pure and Applied Chemistry (IUPAC) reviewed the work done in Dubna and at the LLNL, and did not accept that there was enough evidence to accept ununoctium as an established element.

The report stated, “the three events reported for the Z = 118 isotope have very good internal redundancy but with no anchor to known nuclei do not satisfy the criteria for discovery.” (2)

As a result of its position in the periodic table ununoctium is expected to be classed as a noble gas.

Too little of the element has been synthesized for this to be confirmed, although some calculations indicate ununoctium might in fact be solid at room temperature.

The joint teams at JINR in Dubna and Lawrence Livermore in California have published evidence for the synthesis of elements 113, 114, 115, 116, 117 and 118.

IUPAC has accepted the discoveries of element 114 (ununquadium) and element 116 (ununhexium).
It has not yet considered the evidence for the discovery of element 117 (ununseptium).

IUPAC requires stronger evidence before it will confirm the synthesis of element 113 (ununtrium), element 115 (ununpentium), or element 118 (ununoctium).

UPDATE: The discovery of elements 113, 115, 117 and 118 was formally accepted on December 30, 2015 by IUPAC and IUPAP, completing the seventh row of the periodic table.

Appearance and Characteristics

Harmful effects:

Ununoctium is harmful due to its radioactivity.


Ununoctium is a synthetic radioactive metal and has only been produced in minute amounts.

Uses of Ununoctium

Ununoctium is of research interest only.

Abundance and Isotopes

Abundance earth’s crust: nil

Abundance solar system: parts per trillion by weight, parts per trillion by moles

Cost, pure: $ per 100g

Cost, bulk: $ per 100g

Source: A few atoms ununoctium may have been created via nuclear bombardment of 249Cf with 48Ca ions in a heavy ion accelerator. IUPAC does not accept there is enough evidence to accept ununoctium as an established element.

Isotopes: Ununoctium may have one isotope whose half-life is known very approximately: 294Uuo, with a half-life of 0.89 milliseconds.


1. Oganessian et al., Results of the first 249Cf + 48Ca Experiment. (pdf download)
2. Robert Barber, Paul Karol, Hiromichi Nakahara, Emanuele Vardaci, and Erich Vogt, Discovery of the elements with atomic numbers greater than or equal to 113,. 2011, IUPAC. (pdf download)
3. Photo: ORNL

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