Oganeson is the heaviest element ever made. Scientists think it would be solid at room temperature, but in reality it may be an unreactive noble gas. However, since only a few atoms have been made so far, its properties are not well known. It is the last confirmed element of the estimated 172 that may exist. This element was produced, in 2002, when, by a "hot fusion" reaction of the californium 249Cf atom and calcium 48Ca at the Central Institute for Nuclear Research (JINR), Dubná, Russia.

249Cf  + 48Ca →  294Og  + 3 n

The element is named after Yuri Ts. Oganessian, the team leader. Subsequently, in 2006, by a team of Russian and American scientists, from JINR and the US Lawrence Livermore National Laboratory, respectively, announced that they had indirectly detected a total of three or perhaps four nuclei of oganessian-294, 294Og.

294Og decays by disintegration to 290Lv, and has a half-life (T½) of 0.89 ms.

Due to the very low half-life and the fact that only very few atoms have been isolated, all that is known of their chemical properties is through theoretical studies.

Although it is in group 18 of the noble gases and has been predicted to probably be a solid at 20 ºC.

In the oganeson the relativistic effects are so strong that they affect the valence electrons (the atom's shell structure changes to the Thomas-Fermi electron gas model). In addition, its oxidation states would be limited to +4. It is believed that the structure of the oganeson in compounds such as OgF4 would be tetrahedral.

It is attributed with such a high polarizability that it would give rise to an increase in van der Waals forces compared to the rest of the noble gases. Therefore, it would have physicochemical properties very different from the rest of group 18.

Summary of properties (Og)

Atomic weight[294]
Discoverer (year)unknown (1999)
Natural form- (-)
Electron configuration[Rn] 5f 14 6d10 7s2 7p6
Melting point (ºC)
Boiling point (ºC)
Abundance in earth's crust (ppm)synthetic
Isotope (abundance)
Density g/cm3
Van der Waals radius (pm)
Covalent radius (pm)157
Electronegativity (Pauling)
Vaporization enthalpy (kJ/mol)-
Enthalpy of fusion (kJ/mol)-
Specific heat capacity (J/g·K) at 25ºC and 1 atm-
Thermal conductivity (W/cm·K) at 25ºC and 1 atm-
Oxidation state
Electron affinity (eV)0.06
1st Ionization potential (eV)

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