Ununtrium is a chemical element classified among the transactinide elements on the periodic table of elements. This makes it among the heaviest elements known to man; it is sometimes referred to as a “super heavy element” in a reference to this fact. Like other transactinides, ununtrium is extremely unstable, making it very difficult to observe in the laboratory, and it cannot be found in nature. As a result, scientists are forced to use expensive and time consuming techniques to synthesize it if they wish to study it.

This element is believed to be metallic in nature, and it may share some chemical properties with thallium; some people refer to it as eka-thallium as a result. Given the general patterns which govern the periodic table, scientists can also estimate that ununtrium is probably a very reactive element, much like sodium. This element is also radioactive, like other transactinides. It has an atomic number of 113, and it is identified on the periodic table with the symbol Uut.

This element was jointly discovered by a team of scientists at Lawrence Livermore National Laboratory in the United States and a group in Dubna, Russia, in 2003. In 2004, Japanese researchers at Riken Laboratory managed to synthesize and observe the element as well, making it the first synthetic element to be produced in Japan. The International Union of Pure and Applied Chemistry (IUPAC) has temporarily named the element ununtrium, while it decides which laboratory gets the credit for discovery and the honor of suggesting a name. “Ununtrium,” incidentally, is a systematic element name, following a system used by the IUPAC which identifies unnamed elements by their atomic number; “ununtri” means “one one three,” with “-ium” being a standard suffix for chemical elements.

The Russian team has proposed “becquerelium,” in honor of noted French physicist Henry Becquerel. The Japanese researchers are advocating for “japonium” or “rikenium” in honor of their own research. The dispute over naming may take a while; some elements have had temporary names for several decades while their nomenclature is sorted out.

This element is synthetically produced by first creating element 115, ununpentium. Ununtrium is a decay product of ununpentium. A number of isotopes of ununtrium have been identified, with half lives ranging from milliseconds to minutes. The instability of this element and its isotopes makes it challenging to study; scientists hope that through continued synthetic production of the element, they may be able to identify more stable forms.