Periodic Table of Elements




Ununoctium was discovered by Ninov et al. in the year 1999.

Name: Ununoctium
Symbol: Uuo
Atomic number: 118
Atomic weight: 294
State: presumably a gas
Group, period, block: 18, 7, p
Color: unknown
Classification: Non-metallic
Electron configuration: 5f14 6d10 7s2 7p6

Physical properties

Density: 13.65 g/cm-3
Melting point: no data
Boiling point: 35030[1] K,8030 C,17050 F

Atomic properties

Oxidation states: -1,[2] 0, +1,[5] +2[6], +4[6], +6[2], +8[7]
Electronegativity: no data
Ionization energies: 1st: 839.4 kJmol-1
Covalent radius: 157 pm
Van der Waals radius: no data
  • Uuo
  • Electron Configuration


Ununoctium is an artificial element, and thus a standard atomic mass cannot be given. Like all artificial elements, it has no stable isotopes. The first synthesized isotope was 294Uuo in 2006; it has a half-life of 890 microseconds.