Island of stability



 

The island of stability is a term from nuclear physics that describes the possibility of decay much more slowly.

Contents


The idea of the island of stability was first proposed by 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[1].

A filled shell would have "periodic table.

Half-lives of large isotopes

Fermium is the largest element that can be produced in a nuclear reactor. The stability (half-life of the longest-lived isotope) of elements generally decreases from element 101 to element 109 and then approaches an island of stability with longer-lived isotopes in the range of elements 111 and 114[2]. This is illustrated in the following two tables.

Isotopes of elements 100 through 109[2]
Number Name Longest-lived
isotope 		Half-life of
longest-lived isotope 		Link
100 Isotopes of fermium
101 Isotopes of mendelevium
102 Isotopes of nobelium
103 Isotopes of lawrencium
104 Isotopes of rutherfordium
105 Isotopes of dubnium
106 Isotopes of seaborgium
107 Isotopes of bohrium
108 Isotopes of hassium
109 Isotopes of meitnerium

The following table shows information about the half-lives of isotopes of elements 110 through 120.

Isotopes of elements 110 through 120
Number Name # isotopes (known) # isotopes observed Longest half-life observed (ms) Link
110 Isotopes of darmstadtium
111 Isotopes of roentgenium
112 Isotopes of ununbium
113 Isotopes of ununtrium
114 Isotopes of ununquadium
115 Isotopes of ununpentium
116 Isotopes of ununhexium
117 Isotopes of ununseptium
118 Isotopes of ununoctium
119 ununennium 0 0 N/A Isotopes of ununennium
120 unbinilium 0 0 N/A Isotopes of unbinilium

The neutron sources). However, the isotopes of several of these elements still have too few neutrons to be stable. The island of stability still hasn't been reached, since the island's "shores" have neutron richer nuclides than those produced.

Island of relative stability

232Th (francium extremely short-lived relative to all but the heaviest elements found so far.

Synthesis problems

Manufacturing nuclei in the island of stability may be very difficult, because the nuclei available would not deliver the necessary sum of neutrons. So for the synthesis of isotope 298 of element 114 by using plutonium and calcium, one would require an isotope of plutonium and one of calcium, which have together a sum of at least 298 nucleons (more is better, because at the nuclei reaction some neutrons are emitted). This would require for example in the case of synthesis of element 114 the usage of calcium-50 and plutonium-248. However these isotopes (and heavier calcium and plutonium isotopes) are not available in weighable quantities. This is also the fact for other target/projectile-combinations.

However it may be possible to generate the isotope 298 of element 114, if nuclear transfer reactions would work. One of these reactions may be:

204Hg + 136Xe → 298Uuq + 40Ca + 2n

References

  1. ^ Shell Model of Nucleus. HyperPhysics. Department of Physics and Astronomy, Georgia State University. Retrieved on 2007-01-22.
  2. ^ a b Emsley, John (2001). Nature's Building Blocks, (Hardcover, First Edition), Oxford University Press, (pages 143,144,458). ISBN 0198503407. 
  3. ^ Moller Theoretical Nuclear Chart 1997

See also
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Island_of_stability". A list of authors is available in Wikipedia.