Ununoctium

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Ununoctium is the temporary IUPAC name for the transactinide element having the atomic number 118 and temporary element symbol Uuo. 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 and has the highest atomic number and highest atomic mass assigned to a discovered element.

 

General
Name, symbol, number Ununoctium, Uuo, 118
Chemical series noble gases
Group, period, block 18, 7, p
Appearance Unknown, probably colorless
Standard atomic weight (294)g·mol-1
Electrons per shell 2, 8, 18, 32, 32, 18, 8
Physical properties
Phase liquid (or solid – predicted)
Density (near r.t.) (predicted) 13.65 g·cm−3
Boiling point (extrapolated) 320–380 K
(50–110 °C, 120–220 °F)
Critical point (extrapolated) 439 K, 6.8 MPa
Heat of fusion (extrapolated) 23.5 kJ·mol-1
Heat of vaporization (extrapolated) 19.4 kJ·mol-1
Oxidation states 0, +2, +4
Ionization energies 1st: (calc.) 820–1130 kJ·mol-1
2nd: (extrapolated) 1450 kJ·mol-1
Atomic radius (predicted) 152 pm
Covalent radius (extrapolated) 230 pm
Miscellaneous
CAS registry number 54144-19-3

 

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