Iron-56

<h2 id="relationship-to-nickel-62">Relationship to nickel-62</h2>
<p><a href="/facts/Nickel-62/ePeXd1y1">Nickel-62</a>, a relatively rare isotope of nickel, has a higher <a href="/facts/Nuclear_binding_energy/PU8bREHW">nuclear binding energy</a> per nucleon; this is consistent with having a higher mass-per-nucleon because nickel-62 has a greater proportion of <a href="/facts/Neutron/oRCM1geb">neutrons</a>, which are slightly more massive than <a href="/facts/Proton/clCjepXP">protons</a>. (See the <a href="/facts/Nickel-62/ePeXd1y1">nickel-62</a> article for more).  Light elements undergoing <a href="/facts/Nuclear_fusion/hP0gLDqj">nuclear fusion</a> and heavy elements undergoing <a href="/facts/Nuclear_fission/LfkIylvm">nuclear fission</a> release energy as their nucleons bind more tightly, so 62Ni might be expected to be common. However, during <a href="/facts/Stellar_nucleosynthesis/qEQJdJe6">stellar nucleosynthesis</a> the competition between <a href="/facts/Photodisintegration/7TKyEJtc">photodisintegration</a> and <a href="/facts/Alpha_process/S8cf71rL">alpha capturing</a> causes more <a href="/facts/Nickel-56/3jPqldnR">56Ni</a> to be produced than 62Ni (56Fe is produced later in the star's ejection shell as 56Ni decays).
</p><p>Although nickel-62 has a higher binding energy per nucleon, the conversion of 28 atoms of nickel-62 into 31 atoms of iron-56 releases 0.011 <a href="/facts/Dalton_(unit)/IMATU3vf">Da</a> of energy.  As the <a href="/facts/Universe/XbfpnDmM">universe</a> ages, matter will slowly convert to ever more tightly bound nuclei, approaching 56Fe, ultimately leading to the formation of <a href="/facts/Iron_star/1Qgt5h4d">iron stars</a> over ≈ 101500 years, assuming an <a href="/facts/Future_of_an_expanding_universe/ySer1Ltq">expanding universe without proton decay</a>.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a>
</p>
<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Isotopes_of_iron/GVebbg1n">Isotopes of iron</a></li>
<li><a href="/facts/Iron_star/1Qgt5h4d">Iron star</a></li></ul>

<ul><li><a href="/facts/John_Robert_de_Laeter/jYQj55GI">de Laeter, John Robert</a>; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). <a href="https://doi.org/10.1351%2Fpac200375060683">"Atomic weights of the elements. Review 2000 (IUPAC Technical Report)"</a>. <i><a href="/facts/Pure_and_Applied_Chemistry/9QdCDKxf">Pure and Applied Chemistry</a></i>. 75 (6): 683–800. <a href="/facts/Doi_(identifier)/muM9Etpq">doi</a>:<a href="https://doi.org/10.1351%2Fpac200375060683">10.1351/pac200375060683</a>.</li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Nuclear Binding Energy <a href="http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/nucbin.html#c2" target="_blank">http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/nucbin.html#c2</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Dyson, Freeman J. (1979). "Time without end: Physics and biology in an open universe". Reviews of Modern Physics. 51 (3): 447–460. Bibcode:1979RvMP...51..447D. doi:10.1103/RevModPhys.51.447. <a href="/wiki/Reviews_of_Modern_Physics" target="_blank">/wiki/Reviews_of_Modern_Physics</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
</ol>

Iron-56 open-in-new

Iron-56