This is an old revision of this page, as edited by 72.139.119.165 (talk) at 15:40, 5 January 2006 (Correction of half lives). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.
Revision as of 15:40, 5 January 2006 by 72.139.119.165 (talk) (Correction of half lives)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)The island of stability is a term from nuclear physics, which describes the possibility of elements which have particularly stable "magic numbers" of protons and neutrons. This would allow certain isotopes of some transuranic elements to be far more stable than others, and thus decay much more slowly.
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 numbers of neutrons and protons completely fill the energy levels of a given shell in the nucleus, then the binding energy per nucleon will reach a local minimum 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 is 184, and some possible matching proton numbers are 114, 120 and 126 — which would mean that the most stable possible isotopes would be ununquadium-298, unbinilium-304 and unbihexium-310. None of these isotopes has yet been produced. Isotopes of ununquadium, with 114 protons but fewer than 184 neutrons, have been produced and are significantly slower to decay than isotopes of nearby elements on the periodic table.
The term "particularly stable" is in comparison to the half-lives of slightly lighter or heavier elements; the half-lives of elements in the island of stability are still expected to be measured in mintutes, hours, or days, though some theoretical possibilities include much longer periods.
Island of relative stability
Th (Thorium), U and U (Uranium) are the only naturally occurring isotopes beyond Bismuth that are relatively stable over the current lifespan of the universe. All other isotopes beyond Bismuth are relatively or very unstable. So the main periodic table ends at Bi, with an island at thorium and uranium.
The relatively unstable elements reach up to element 106 Seaborgium (Sg), after which they get very unstable before reaching the island of stability, set in the ocean of instability.
External links
- The synthesis of spherical superheavy nuclei in 48Ca induced reactions
- New elements discovered and the island of stability sighted
- First postcard from the island of nuclear stability
- Second postcard from the island of stability
- Superheavy Elements "Island of Stability"
- Superheavy elements
- Can superheavy elements (such as Z=116 or 118) be formed in a supernova? Can we observe them?
See also
- Island of stability : Ununquadium – Unbinilium – Unbihexium
- Isotope table and Isotope table (divided) - the best visualization of the island of stability
- Periodic table and Periodic table (extended)