The atomic number of Dubnium is 105. Dubnium is a synthetic element that was first synthesized in 1968 by a team of Russian and American scientists at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia. It is named after Dubna, the city where it was discovered. Dubnium is a highly radioactive element, and its most stable isotope, Dubnium-268, has a half-life of about 28 hours. Due to its short half-life and limited availability, Dubnium is primarily studied for scientific research purposes and has no known practical applications.