Ununoctium: Atomic Number, Electron Configuration & Properties

Ununoctium, now known as Oganesson (Og), eka-radon or element 118 is a synthetic or transactinide chemical element with symbol Uuo and atomic number 118. It was first synthesized in 2002 by a joint team of Russian and American scientists at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia, and the Lawrence Livermore National Laboratory (LLNL) in California, USA.

It was formally named on 28 November 2016. The name Oganesson honors the nuclear physicist Yuri Oganessian, who played a leading role in the discovery of the heaviest elements in the periodic table. It is one of only two elements named after a person who was alive at the time of naming, the other being seaborgium, and the only element whose eponym is alive today.

Ununoctium is a member of the noble gases group in the periodic table and is expected to have properties similar to other noble gases such as helium, neon, argon, krypton, xenon, and radon. It is a highly radioactive element, and its most stable known isotope, ununoctium-294, has a half-life of only about 0.89 milliseconds.

Due to its extremely short half-life and the difficulty in producing and studying it, very little is known about the chemical and physical properties of ununoctium. Its existence was confirmed through experiments involving nuclear fusion reactions, typically using heavy-ion accelerators.

Properties of Ununoctium

Atomic number118
Atomic massApproximately 294 u
Electron configuration[Rn] 5f14 6d10 7s2 7p6 (predicted)
GroupGroup 18 (Noble gases)
PeriodPeriod 7
Element categoryNoble gas
Melting pointUnknown (predicted to be very low)
Boiling pointUnknown (predicted to be very low)
Ionization energyUnknown
Oxidation states0 (predicted)
Atomic radiusUnknown
Covalent radiusUnknown
Crystal structureUnknown
Common isotopesUuo-294 (most stable with a half-life of approximately 0.89 milliseconds)

Electron configuration of ununoctium (Uuo)

The electron configuration of ununoctium (Uuo) is predicted to follow the general pattern for noble gases, specifically for the element that follows radon (Rn) in the periodic table. Ununoctium is expected to have an electron configuration of [Rn] 5f14 6d10 7s2 7p6.

This configuration indicates that ununoctium would have a completely filled outermost electron shell, which is characteristic of noble gases. The [Rn] part represents the electron configuration of radon, the noble gas element preceding ununoctium in the periodic table. The 5f, 6d, and 7s orbitals are filled in sequence before the outermost 7p orbital, resulting in a stable electron configuration.

Related elements to ununoctium (Uuo)

These elements are all members of Group 18 (also known as Group 0 or Group VIII) of the periodic table, commonly referred to as the noble gases or inert gases. They share similar chemical properties due to having full valence electron shells, something that make them relatively unreactive under normal conditions. Ununoctium (Uuo) is the heaviest and the most recently discovered element in this group.

ElementSymbolAtomic NumberGroupPeriod