[M.D. Holloway]

The idea of the island of stability was first proposed by Glenn T. Seaborg. The hypothesis is that the atomic nucleus is built up in "shells" in a manner similar to the electron shells in atoms. In both cases shells are just groups of quantum energy levels that are relatively close to each other. Energy levels from quantum states in two different shells will be separated by a relatively large energy gap. So when the number of neutrons and protons completely fill the energy levels of a given shell in the nucleus, the binding energy per nucleon will reach a local maximum and thus that particular configuration will have a longer lifetime than nearby isotopes that do not have filled shells.

A filled shell would have "magic numbers" of neutrons and protons. One possible magic number of neutrons for spherical nuclei is 184, and some possible matching proton numbers are 114, 120 and 126 – which would mean that the most stable spherical isotopes would be ununquadium-298, unbinilium-304 and unbihexium-310. Of particular note is Ubh-310, which would be "doubly magic" (both its proton number of 126 and neutron number of 184 are thought to be magic) and thus the most likely to have a very long half-life. (The next lighter doubly-magic spherical nucleus is lead-208, the heaviest stable nucleus and most stable heavy metal.) Isotopes of elements in the range between 110 through 114 have been found to decay more slowly than isotopes of nuclei nearby in the periodic table.

However, recent research indicates that large nuclei are deformed, causing magic numbers to shift. Hassium-270 is now believed to be doubly-magic nucleus, with deformed magic numbers 108 and 162. Its half-life may be as high as 23 seconds.

If there is such a thing as the island of stability with atomic numbers in level 8 or above, it is believed by many that they would be able to support their own gravitational field...