 Initially , by analogy with the neutron magic number 126 , the next proton shell was also expected to occur at element 126 , too far away from the synthesis capabilities of the mid @-@ 20th century to achieve much theoretical attention . In 1966 , new values for the potential and spin @-@ orbit interaction in this region of the periodic table contradicted this and predicted that the next proton shell would occur instead at element 114 , and that nuclides in this region would be as stable against spontaneous fission as many heavy nuclei such as lead @-@ 208 . The expected closed neutron shells in this region were at neutron number 184 or 196 , thus making 298Fl and <unk> candidates for being doubly magic . 1972 estimates predicted a half @-@ life of about a year for 298Fl , which was expected to be near a large island of stability with the longest half @-@ life at darmstadtium @-@ 294 ( 1010 years , comparable to that of 232Th ) . After the synthesis of the first isotopes of elements 112 through 118 at the turn of the 21st century , it was found that the synthesized neutron @-@ deficient isotopes were stabilized against fission . In 2008 it was thus hypothesized that the stabilization against fission of these nuclides was due to their being oblate nuclei , and that a region of oblate nuclei was centred on 288Fl . Additionally , new theoretical models showed that the expected gap in energy between the proton orbitals <unk> / 2 ( filled at element 114 ) and 2f5 / 2 ( filled at element 120 ) was smaller than expected , so that element 114 no longer appeared to be a stable spherical closed nuclear shell . The next doubly magic nucleus is now expected to be around 306Ubb , but the expected low half @-@ life and low production cross section of this nuclide makes its synthesis challenging . Nevertheless , the island of stability is still expected to exist in this region of the periodic table , and nearer its centre ( which has not been approached closely enough yet ) some nuclides , such as 291Uup and its alpha- and beta @-@ decay daughters , may be found to decay by positron emission or electron capture and thus move into the centre of the island . Due to the expected high fission barriers , any nucleus within this island of stability decays exclusively by alpha decay and perhaps some electron capture and beta decay , both of which would bring the nuclei closer to the beta stability line where the island is expected to be . Electron capture is needed to reach the island , which is problematic because it is not certain that electron capture becomes a major decay mode in this region of the chart of nuclides . 
