The electron shell of biunoctium
Chemical properties
Name, symbol, number: biunoctium, Buo, 218
Element category: unknown (possible noble gas)
Group, period, block: 18, 9, p
Standard atomic weight: [622][1]
Electron configuration: [Uho] 6g187f148d109p6


Phase: Unknown
Density (near r.t.): Unknown
Melting point: Unknown
Boiling point: Unknown
Oxidation states: Unknown
Atomic radius: Unknown
Discoverer None of as yet
Location discovered None of as yet
Date discovered None of as yet

Biunoctium, also known as eka-unhexoctium or element 218, is the temporary name of a hypothetical superheavy chemical element in the periodic table that has the temporary symbol Buo and has the atomic number 218. In the periodic table of elements, it is a p-block element and the last one of the 9th period. As of 2012, no attempt has been made to synthesize this element. It is predicted to be a noble gas.[3]


Currently, biunoctium goes under a systematic temporary element name. It is the heaviest element predicted, with the most protons. Since it is very far in the periodic table and has never been synthesized, very little is known about this element, and it is unknown whether a superheavy element like this could physically exist.[4]


No name has yet been officially suggested for the element. According to current guidelines from IUPAC, the ultimate name for all new elements should end in "-ium", which means the name for biunoctium may end in "-ium", not "-on", even if biunoctium turns out to be a noble gas, which traditionally have names ending in "-on" (with the exception of helium, which was not known to be a noble gas when it was discovered).[5]

Extrapolated chemical propertiesEdit

Biunoctium is a superheavy element, therefore it has a very large atom that is significantly radioactive. Since it is very far in the periodic table and has never been synthesized, very little is known about this element.

Taking the position in the periodic table as a noble gas, it is predicted to be a heavier homologue to the lighter ones. Even though, it may be a solid under relativistic effects, like ununoctium.


Main article: Isotopes of biunoctium

If this element exists, its most stable isotope would probably be biunoctium-622.[6]


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