Search results
Results from the WOW.Com Content Network
In atomic physics, even–even (EE) nuclei are nuclei with an even number of neutrons and an even number of protons. Even-mass-number nuclei, which comprise 151/251 = ~60% of all stable nuclei, are bosons, i.e. they have integer spin. The vast majority of them, 146 out of 151, belong to the EE class; they have spin 0 because of pairing effects. [1]
Among the 41 even-Z elements that have a stable nuclide, only two elements (argon and cerium) have no even–odd stable nuclides. One element (tin) has three. There are 24 elements that have one even–odd nuclide and 13 that have two even–odd nuclides. The lightest example of this type of nuclide is 3 2 He and the heaviest is 207 82 Pb.
Stable even–even nuclides number as many as three isobars for some mass numbers, and up to seven isotopes for some atomic numbers. Conversely, of the 251 known stable nuclides, only five have both an odd number of protons and odd number of neutrons: hydrogen-2 , lithium-6, boron-10, nitrogen-14, and tantalum-180m.
The stability of 4 He also leads to the absence of stable isobars of mass number 5 and 8; indeed, all nuclides of those mass numbers decay within fractions of a second to produce alpha particles. Magic effects can keep unstable nuclides from decaying as rapidly as would otherwise be expected.
An even number of protons or neutrons is more stable (higher binding energy) because of pairing effects, so even–even nuclides are much more stable than odd–odd. One effect is that there are few stable odd–odd nuclides: in fact only five are stable, with another four having half-lives longer than a billion years.
A chart or table of nuclides maps the nuclear, or radioactive, behavior of nuclides, as it distinguishes the isotopes of an element.It contrasts with a periodic table, which only maps their chemical behavior, since isotopes (nuclides that are variants of the same element) do not differ chemically to any significant degree, with the exception of hydrogen.
Contrary to observed for charge distributions no odd-even effect on fragments mass number (A) is observed. This result is interpreted by the hypothesis that in fission process always there will be nucleon pair breaking, which may be proton pair or neutron pair breaking in low energy fission of uranium-234 , uranium-236 , [ 3 ] and plutonium-240 ...
There are 6 stable nuclides and one radioactive primordial nuclide with neutron number 82 (82 is the neutron number with the most stable nuclides, since it is a magic number): barium-138, lanthanum-139, cerium-140, praseodymium-141, neodymium-142, and samarium-144, as well as the radioactive primordial nuclide xenon-136, which decays by a very ...