Credit: Galyna Andrushko | Shutterstock
Atomic Number: 117
Atomic Symbol: Uus
Atomic Weight: 
Melting Point: Unknown
Boiling Point: Unknown
Word origin: Element 117 is officially unnamed; ununseptium is its temporary name. The name means one-one-seven (its atomic number) in Latin.
Discovery: Element 117 was discovered in 2010 and jointly announced on April 5 of that year by scientists at the Joint Institute for Nuclear Research in Dubna, Russia, and scientists at the Lawrence Livermore National Laboratory in California.
Properties of ununseptium
Ununseptium is a radioactive, artificially produced element about which little is known. It is expected to be a solid, but its classification is unknown. It is a member of the halogen group.
Ununseptium has two isotopes with known half-lives and two with unknown half-lives. The most stable isotope is 294Uus, with a half-life of about 80 milliseconds. It decays through alpha decay. Ununseptium’s other isotopes are suspected to decay through both alpha decay and spontaneous fission.
The atomic weight for manmade transuranium elements is based on the longest-lived isotope. These atomic weights should be considered provisional since a new isotope with a longer half-life could be produced in the future. [See Periodic Table of the Elements]
Sources of ununseptium
Uses of ununseptium
Since only a few atoms of ununseptium have ever been made, it has no practical uses outside of scientific study.