Wikipedia:Today's featured article/December 15, 2015

Ununseptium is the current name of the artificial chemical element with atomic number 117. The second-heaviest known element and second-to-last element of the 7th period of the periodic table, its discovery was announced in Dubna, Russia, by a Russian–American collaboration in 2010, making it the most recently discovered element. One of its daughter isotopes was created in 2011, partially confirming the results. The experiment was repeated successfully by the same collaboration in 2012 and by a joint German–American team in 2014. When these experiments have been examined and verified by the Joint Working Party, the discoverers will be invited to give the element an official name. Some of ununseptium's isotopes are expected to lie within the island of stability, a predicted group of nuclides of enhanced stability with atomic numbers around 120, but the isotopes of ununseptium created so far have had predicted half-lives of less than one second. Like fluorine, chlorine, and other halogens, ununseptium is expected to be a group 17 element, but it is not currently expected to be a halogen, as some of its properties are likely to be different due to relativistic effects.