The recently discovered elements 113, 115, 117, and 118 have been going by the monikers ununtrium, ununpentium, ununseptium, and ununoctium, respectively. On 8 June those tongue-tying systematic names were discarded and the new elements christened—at least provisionally—nihonium (Nh, 113), moscovium (Mc, 115), tennessine (Ts, 117), and oganesson (Og, 118). The International Union of Pure and Applied Chemistry (IUPAC) unveiled the names and symbols, which were proposed by the new elements’ discoverers, and opened a five-month-long public-comment period.
IUPAC maintains specific guidelines for naming new elements. Last December, IUPAC assigned priority for the discovery of element 113 to researchers at the RIKEN research institute in Japan. A collaboration between the Joint Institute for Nuclear Research (JINR) in Russia, Oak Ridge National Laboratory (ORNL) in Tennessee, and Lawrence Livermore National Laboratory (LLNL) in California received credit for elements 115 and 117. Element 118 went to a joint JINR–LLNL team. By tradition, naming rights go to the discoverers.
According to IUPAC, elements can take their names from mythology, a mineral, a place, a property of the element, or a scientist. The newest names follow a long trend of honoring people or places. The RIKEN researchers proposed nihonium for the first element to be discovered in Asia. The Japanese call their country Nihon or Nippon. The JINR-ORNL-LLNL collaboration went with moscovium for the Moscow region, which hosts the JINR where Mc, Ts, and Og were discovered. Tennessine is for Tennessee, home to ORNL, which produced actinide target isotopes to create the heavy elements. And oganesson honors Yuri Oganessian, the 83-year-old leader of the superheavy element search at JINR.
A simulation of the nucleus of element 117, which will likely receive the name tennessine (Ts). Credit: Kwei-Yu Chu/LLNL
Nihonium and moscovium should have a familiar ring to them—most of the elements on the periodic table end in -um or -ium. But tennessine fits in group 17 of the periodic table under fluorine, chlorine, and the other halogen elements, so it ended up with the -ine ending. Oganesson, with its -on ending, falls under the noble gases just below radon.
Another rule forbids names or symbols that have been previously used for another element, even if that name is no longer in use. The symbol Tn, perhaps the more natural choice than Ts to represent tennessine, suffered such a disqualification. In the early 20th century, isotopes of elements often received their own names, and in 1923 Tn was assigned to the isotope thoron (radon-220).
Researchers create new superheavy elements by firing heavy-ion projectiles at target nuclei. Occasionally, the projectile and target fuse and produce a new nuclide that survives long enough to be detected. (See the article by Yuri Oganessian and Krzysztof Rykaczewski in Physics Today, August 2015, page 32.)
To create Nh, the RIKEN group, led by Kosuke Morita, shot zinc-70 projectiles at a bismuth-209 target during a nearly decade-long effort. Researchers at JINR used radioactive actinide targets bombarded by calcium-48 projectiles. Americium-243 was used to make Mc, berkelium-249 to make Ts, and californium-249 to make Og.
The inclusion of Nh, Mc, Ts, and Og completes the seventh row of the periodic table, which as recently as 2010 was missing six elements. when the public comments period closes on 8 november, iupac will officially accept the new names. researchers, of course, are already looking for elements in the eighth row.
The Week in Physics" is likely a reference to the regular updates or summaries of new physics research, such as those found in publications like Physics Today from AIP Publishing or on news aggregators like Phys.org.
