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There are 145 stable even–even nuclides, forming ~58% of the 251 stable nuclides. There are also 22 primordial long-lived even–even nuclides. As a result, many of the 41 even-numbered elements from 2 to 82 have many primordial isotopes. Half of these even-numbered elements have six or more stable isotopes. The lightest stable even-even ...
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 ( deuterium ), lithium-6 , boron-10 , nitrogen-14 , and tantalum-180m .
A set of nuclides with equal proton number (atomic number), i.e., of the same chemical element but different neutron numbers, are called isotopes of the element. Particular nuclides are still often loosely called "isotopes", but the term "nuclide" is the correct one in general (i.e., when Z is not fixed).
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.
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]
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The greater the number of protons, the more neutrons are required to stabilize a nuclide; nuclides with larger values for Z require an even larger number of neutrons, N > Z, to be stable. The valley of stability is formed by the negative of binding energy, the binding energy being the energy required to break apart the nuclide into its proton ...