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) |
| 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 | – |
| Oxide(s) | – |
| Hydride(s) | – |
| Chloride(s) | – |
| 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 heavy ion cyclotron U-400 in Dubna, where ununoctium may have been synthesized.
Discovery of Ununoctium
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).
Appearance and Characteristics
Harmful effects:
Ununoctium is harmful due to its radioactivity.
Characteristics:
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.
References
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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