#105 DubniumDubnium is a synthetic chemical element with symbol Db and atomic number 105. Dubnium is highly radioactive: the most stable known isotope, dubnium-268, has a half-life of about 28 hours. This greatly limits the extent of research on dubnium. Dubnium does not occur naturally on Earth and is produced artificially. Atomic mass:(262.0) amu Melting point:Unknown Boiling point:Unknown Density:Unknown |