Periodic Table of Elements




Ununseptium was discovered by a group of scientists from Russia and USA in 2009-2010.

Name: Ununseptium
Symbol: Uus
Atomic number: 117
Atomic weight: 294
State: presumably a solid
Group, period, block: 17, 7, p
Color: unknown
Classification: unknown
Electron configuration: 5f14 6d10 7s2 7p5

Physical properties

Density: no data
Melting point: 573773 K,300500 C,572932 (predicted) F
Boiling point: 823 K,550 C,1022 (predicted) F

Atomic properties

Oxidation states: -1, +1, +3, +5
Electronegativity: no data
Ionization energies: 1st: 742.9 kJmol-1
Covalent radius: 165 pm
Van der Waals radius: no data
  • Uus
  • Electron Configuration


Ununseptium is an artificial element, and thus a standard atomic mass cannot be given. Like all artificial elements, it has no stable isotopes. The synthesized isotopes in 2009 were 293Uus and 294Uus. The longer-lived isotope is 294Uus with a half-life of 78 ms.