Ununoctium

General properties
Name, symbol, number	ununoctium, Uuo, 118
Element category	unknown
Group, period, block	18, 7, p
Standard atomic weight	(294)
Electron configuration	[Rn] 5f14 6d10 7s2 7p6 (predicted) 2, 8, 18, 32, 32, 18, 8 (predicted)
History
Discovery	Joint Institute for Nuclear Research and Lawrence Livermore National Laboratory (2002)

Ununoctium is the temporary IUPAC name for the transactinide element having the atomic number 118 and temporary element symbol Uuo. It is also known as eka-radon or element 118, and on the periodic table of the elements it is a p-block element and the last one of the 7th period. Ununoctium is currently the only synthetic member of Group 18. It has the highest atomic number and highest atomic mass of all the elements discovered so far.

The radioactive ununoctium atom is very unstable, and since 2002, only three or possibly four atoms of the isotope ²⁹⁴Uuo have been detected. While this allowed for very little experimental characterization of its properties and possible compounds, theoretical calculations have resulted in many predictions, including some unexpected ones. For example, although ununoctium is a member of Group 18, it may possibly not be a noble gas, unlike all the other Group 18 elements. It was formerly thought to be a gas but is now predicted to be a solid under normal conditions due to relativistic effects.

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