Ununquadium Traditional Cache

Ununquadium is the temporary name of a radioactive chemical element with the temporary symbol Uuq and atomic number 114.

About 80 decays of atoms of ununquadium have been observed to date, 50 directly and 30 from the decay of the heavier elements ununhexium and ununoctium. All decays have been assigned to the four neighbouring isotopes with mass numbers 286-289. The longest-lived isotope currently known is 289Uuq with a half-life of ~2.6 s, although there is evidence for an isomer, 289bUuq, with a half-life of ~66 s, that would be one of the longest-lived nuclei in the superheavy element region.

Initial chemical studies have strongly indicated that ununquadium possesses non-'eka'-lead properties and appears to behave as the first superheavy element that portrays noble-gas-like properties due to relativistic effects. However, more recent experiments using a different set-up have indicated that ununquadium might have metallic properties.

In December 1998, scientists at Dubna (Joint Institute for Nuclear Research) in Russia bombarded a ²⁴⁴Pu target with ⁴⁸Ca ions. A single atom of ununquadium, decaying by 9.67 MeV alpha-emission with a half-life of 30 s, was produced and assigned to ²⁸⁹114. This observation was subsequently published in January 1999. However, the decay chain observed has not been repeated and the exact identity of this activity is unknown, although it is possible that it is due to a meta-stable isomer, namely ^289mUuq.

In March 1999, the same team replaced the ²⁴⁴Pu target with a ²⁴²Pu one in order to produce other isotopes. This time two atoms of ununquadium were produced, decaying by 10.29 MeV alpha-emission with a half-life of 5.5 s. They were assigned as ²⁸⁷Uuq. Once again, this activity has not been seen again and it is unclear what nucleus was produced. It is possible that it was a meta-stable isomer, namely ^287mUuq.

The now-confirmed discovery of ununquadium was made in June 1999 when the Dubna team repeated the ²⁴⁴Pu reaction. This time, two atoms of element 114 were produced decaying by emission of 9.82 MeV alpha particles with a half life of 2.6 s.

This activity was initially assigned to ²⁸⁸Uuq in error, due to the confusion regarding the above observations. Further work in Dec 2002 has allowed a positive reassignment to ²⁸⁹114.

In May 2009, the Joint Working Party (JWP) of IUPAC published a report on the discovery of copernicium in which they acknowledged the discovery of the isotope ²⁸³Cn. This therefore implies the de facto discovery of ununquadium, from the acknowledgment of the data for the synthesis of ²⁸⁷Uuq and ²⁹¹Uuh, relating to ²⁸³Cn, although this may not be determined as the first synthesis of the element. An impending report by the JWP will discuss these issues.

The discovery of ununquadium, as ²⁸⁷Uuq and ²⁸⁶Uuq, was confirmed in January 2009 at Berkeley. This was followed by confirmation of ²⁸⁸Uuq and ²⁸⁹Uuq in July 2009 at the GSI.

Ununquadium (Uuq) is a temporary IUPAC systematic element name. The element is often referred to as element 114, for its atomic number. According to IUPAC recommendations, the discoverer(s) of a new element has the right to suggest a name. No naming suggestions have yet been given by the (claimant) discoverers.