Periodic Table of Elements




Ununtrium was discovered by Joint Institute for Nuclear Research, Lawrence Livermore in the year 2003.

Name: Ununtrium
Symbol: Uut
Atomic number: 113
Atomic weight: 284.18
State: presumably a solid
Group, period, block: 13, 7, p
Color: unknown
Classification: unknown presumably post-transition metals
Electron configuration: 5f14 6d10 7s2 7p1

Physical properties

Density: 18 g/cm-3
Melting point: 700 K,430 C,810 (predicted) F
Boiling point: 1400 K,1100 C,2000 (predicted) F

Atomic properties

Oxidation states: 1, 3, 5
Electronegativity: no data
Ionization energies: 1st: 704.9 kJmol-1
Covalent radius: 136 pm
Van der Waals radius: no data
  • Uut
  • Electron Configuration


Ununtrium is an artificial element, and thus a standard atomic mass cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 284Uut as a decay product of 288Uup in 2003. The first isotope to be directly synthesized was 278Uut in 2004. There are 6 known radioisotopes from 278Uut to 286Uut. The longest-lived isotope is 286Uut with a half-life of 19.6 seconds.