Nobelium is a man-made, radioactive element denoted by the atomic symbol, No. It has an atomic number of 102 and an atomic weight of 259. Ten isotopes of nobelium have been produced. The longest lived isotope, nobelium-259, has a half-life of 58 hours...

Nobelium (pronounced /noʊˈbiːliəm/, /noʊˈbɛliəm/), also known as unnilbium (/juːˈnɪlbiəm/, symbol Unb), is a synthetic element with the symbol No and atomic number 102. A radioactive metallic transuranic element in the actinide series,...