Nickel-62

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Nickel-62, 62Ni
General
Spin
0
Binding energy8794.553±0.007 keV
Isotopes of nickel
Complete table of nuclides

Nickel-62 is an isotope of nickel having 28 protons and 34 neutrons.

It is a

stable isotope, with the highest binding energy per nucleon of any known nuclide (8.7945 MeV).[1][2] It is often stated that 56Fe
is the "most stable nucleus", but only because 56Fe has the lowest mass per nucleon (not binding energy per nucleon) of all nuclides. The lower mass per nucleon of 56Fe is possible because 56Fe has 26/56 ≈ 46.43% protons, while 62Ni has only 28/62 ≈ 45.16% protons. Protons are less massive than neutrons, meaning that the larger fraction of protons in 56Fe lowers its mean mass-per-nucleon ratio in a way that has no effect on its binding energy.

Properties

The high binding energy of nickel isotopes in general makes nickel an "end product" of many nuclear reactions (including

cobalt-56
and then stable iron-56.

Relationship to iron-56

The second and third most tightly bound nuclei are those of 58Fe and 56Fe, with binding energies per nucleon of 8.7922 MeV and 8.7903 MeV, respectively.[3]

As noted above, the isotope 56Fe has the lowest mass per nucleon of any nuclide, 930.412 MeV/c2, followed by 62Ni with 930.417 MeV/c2 and 60Ni with 930.420 MeV/c2. As noted, this does not contradict binding numbers because 62Ni has a greater proportion of neutrons which are more massive than protons.

If one looks only at the nuclei, without including the electrons, 56Fe again shows the lowest mass per nucleon (930.175 MeV/c2), followed by 60Ni (930.181 MeV/c2), and 62Ni (930.187 MeV/c2).

The misconception of 56Fe's higher nuclear binding energy probably originated from astrophysics.

zinc-60, which would be produced in the next step, after addition of another "alpha
" (or more properly termed, helium nucleus).

Nonetheless, 28 atoms of nickel-62 fusing into 31 atoms of iron-56 releases 0.011 

u of energy; hence the future of an expanding universe without proton decay includes iron stars
rather than "nickel stars".

See also

References

  1. ^ "The Most Tightly Bound Nuclei". hyperphysics.phy-astr.gsu.edu. Retrieved October 23, 2019.
  2. S2CID 250846252
    .
  3. ^ WWW Table of Atomic Masses. Archived 2010-11-24 at the Wayback Machine G. Audi, A.H. Wapstra and C. Thibault (2003). Nuclear Physics A, 729, p. 337.
  4. doi:10.1119/1.17828
    .
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