Wikipedia:Today's featured article/June 3, 2018
Dubnium is an artificially produced chemical element with symbol Db and atomic number 105. It is highly radioactive: the most stable known isotope, dubnium-268, has a half-life of just over a day. Credit for discovery of the element was contested between the Soviet Joint Institute for Nuclear Research and American Lawrence Berkeley Laboratory beginning in 1970; the dispute was resolved in 1993 by an official investigation of the IUPAC/IUPAP Joint Working Party, which awarded joint credit. The element was officially named in 1997 after the town of Dubna, the site of the Soviet institute. Dubnium should share most of its chemical properties, such as its valence electron configuration and a dominant +5 oxidation state, with other group 5 elements, such as vanadium, niobium, and tantalum, with a few anomalies due to relativistic effects. Solution chemistry experiments have revealed that dubnium often behaves more like niobium than tantalum, breaking periodic trends. (Full article...)