physburn writes: The Guardian reports that four new elements, with atomic numbers 113, 115, 117, and 118, have been formally added to the periodic table. The International Union of Pure and Applied Chemistry has now initiated the process of formalizing names and symbols for these elements. "The RIKEN collaboration team in Japan have fulfilled the criteria for element Z=113 and will be invited to propose a permanent name and symbol." 115 and 117, with the temporary names of ununpentium and ununseptium, will be named by researchers from Oak Ridge and Lawrence Livermore national labs in the U.S., as well as from the Joint Institute for Nuclear Research in Russia. 118, known for now as ununoctium, will be named by the same group minus the Oak Ridge researchers. Professor Paul Karol said, "A particular difficulty in establishing these new elements is that they decay into hitherto unknown isotopes of slightly lighter elements that also need to be unequivocally identified, but in the future we hope to improve methods that can directly measure the atomic number, Z."