Search results
Results from the WOW.Com Content Network
Even-mass-number nuclides, which comprise 150/251 = ~60% of all stable nuclides, are bosons, i.e., they have integer spin. 145 of the 150 are even-proton, even-neutron (EE) nuclides, which necessarily have spin 0 because of pairing. The remainder of the stable bosonic nuclides are five odd-proton, odd-neutron stable nuclides (2 1 H, 6 3 Li, 10 ...
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.
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.
(t 1/2 = 4.5 × 10 9 years) of uranium is still fairly abundant in nature, but the shorter-lived isotope 235 U (t 1/2 = 0.7 × 10 9 years) is 138 times rarer. About 34 of these nuclides have been discovered (see List of nuclides and Primordial nuclide for details). The second group of radionuclides that exist naturally consists of radiogenic ...
Examples include boron-10, carbon-12, and nitrogen-14 (as N − Z = 0 for each pair), or boron-12, carbon-14, and nitrogen-16 (as N − Z = 2 for each pair). Beyond the neutron drip line along the lower left, nuclides decay by neutron emission. Beyond the proton drip line along the upper right, nuclides decay by proton emission. Drip lines have ...
The formula does not consider the internal shell structure of the nucleus. The semi-empirical mass formula therefore provides a good fit to heavier nuclei, and a poor fit to very light nuclei, especially 4 He. For light nuclei, it is usually better to use a model that takes this shell structure into account.
All even proton numbers 2 ≤ Z ≤ 102 have at least two beta-decay stable nuclides, with exactly two for Z = 4 (8 Be and 9 Be – the former having an extremely short half-life) and 6 (12 C and 13 C). Also, the only even neutron numbers with only one beta-decay stable nuclide are 0 (1 H) and 2 (4 He); at least two beta-decay stable nuclides ...
[4] [5] Scientists have long searched for long-lived heavy isotopes outside of the valley of stability, [6] [7] [8] hypothesized by Glenn T. Seaborg in the late 1960s. [9] [10] These relatively stable nuclides are expected to have particular configurations of "magic" atomic and neutron numbers, and form a so-called island of stability.