Alternative periodic tables quantum numbers of the electron configuration, hence it has a four-dimensional base. In Theodor Benfey's periodic table (1964), the elements form a two-dimensional spiral, starting from hydrogen, and folding their way around two peninsulars, the transition metals, and lanthanides and actinides. A superactinide island is already slotted in. The Chemical Galaxy (2004) is organized in a similar way. Timothy Stowe's physicist's periodic table is three-dimensional with the three axes representing the principal quantum number, orbital quantum number, and orbital magnetic quantum number. Helium is again a group 2 element. Paul Giguère's 3-D periodic table consists of 4 connected billboards with
Extended periodic table periodic table would quite possibly end around "Z" = 130. Beyond element 164, the fissility line defining the limit of stability with respect to spontaneous fission may converge with the neutron drip line, posing a limit to the existence of heavier elements. Nevertheless, further magic numbers have been predicted at "Z" = 210, 274, and 354 and "N" = 308, 406, 524, 644, and 772, with two beta-stable doubly magic nuclei found at 210 and 274; the same calculation method reproduced the predictions for Fl and 164. Although additional stability toward alpha decay and fission are predicted for these nuclei,