Dubnium

Dubnium is a synthetic, highly radioactive transition metal that does not occur naturally on Earth. Scientists create it in particle accelerators by colliding atomic nuclei, then identify it from the radiation released as its atoms decay. Its longest-lived known isotope lasts about 16 hours, so only tiny numbers of atoms can be studied. Experiments have confirmed some chemistry expected for a transition metal, including a tendency to form compounds in the +5 oxidation state, but much of dubnium’s behavior remains based on predictions. It has no practical or commercial uses; researchers make it to investigate the chemistry and nuclear properties of superheavy elements.