transuranic element

Chemical element with an atomic number of 93 or more – that is, with a greater number of protons in the nucleus than has uranium. All transuranic elements are radioactive. Neptunium and plutonium are found in nature; the others are synthesized in nuclear reactions.

Research in transuranics is pursued mainly at the Lawrence radiation laboratories of the University of California at Berkeley; the Joint Institute for Nuclear Research in Dubna, USSR; and the Institute for Heavy-Ion Research in Darmstadt, Germany. These institutes have produced a number of new elements over the last few decades, in the quest to reach a predicted ‘island of stability’ at higher atomic numbers.