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Primordial nuclide
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<h2 id="stability">Stability</h2> <p>All of the known 251 <a href="/facts/Stable_nuclide/vC0VVvqN">stable nuclides</a>, plus another 35 nuclides that have <a href="/facts/Half-life/kGVH8BAB">half-lives</a> long enough to have survived from the formation of the Earth, occur as primordial nuclides. These 35 primordial radionuclides represent <a href="/facts/Isotope/KD9B1y6o">isotopes</a> of 28 separate <a href="/facts/Chemical_element/0jducgWD">elements</a>. <a href="/facts/Cadmium/wXkV2eIX">Cadmium</a>, <a href="/facts/Tellurium/v7QvfIvS">tellurium</a>, <a href="/facts/Xenon/9E3XR69R">xenon</a>, <a href="/facts/Neodymium/GzDkTIoI">neodymium</a>, <a href="/facts/Samarium/09K3kl93">samarium</a>, <a href="/facts/Osmium/1TjXD69n">osmium</a>, and <a href="/facts/Uranium/n2sGWBzU">uranium</a> each have two primordial radioisotopes (<a href="/facts/Cadmium-113/2F42oNDz">113Cd</a>, <a href="/facts/Cadmium-116/2F42oNDz">116Cd</a>; <a href="/facts/Tellurium-128/cE0X04xU">128Te</a>, <a href="/facts/Tellurium-130/cE0X04xU">130Te</a>; <a href="/facts/Xenon-124/Yz78R52h">124Xe</a>, <a href="/facts/Xenon-136/Yz78R52h">136Xe</a>; <a href="/facts/Neodymium-144/ojKx8hWx">144Nd</a>, <a href="/facts/Neodymium-150/ojKx8hWx">150Nd</a>; <a href="/facts/Samarium-147/e5wQw5B0">147Sm</a>, <a href="/facts/Samarium-148/e5wQw5B0">148Sm</a>; <a href="/facts/Osmium-184/7psC8ylM">184Os</a>, <a href="/facts/Osmium-186/7psC8ylM">186Os</a>; and <a href="/facts/Uranium-235/pe0RznDM">235U</a>, <a href="/facts/Uranium-238/QhcHm6q8">238U</a>). </p><p>Because the <a href="/facts/Age_of_the_Earth/MxNh2Q11">age of the Earth</a> is 4.58×109 years (4.58 billion years), the <a href="/facts/Half-life/kGVH8BAB">half-life</a> of the given nuclides must be greater than about 108 years (100 million years) for practical considerations. For example, for a nuclide with half-life 6×107 years (60 million years), this means 77 half-lives have elapsed, meaning that for each <a href="/facts/Mole_(unit)/kCMFwCc0">mole</a> (6.02×1023 atoms) of that nuclide being present at the formation of Earth, only 4 atoms remain today. </p><p>The seven shortest-lived primordial nuclides (i.e., the nuclides with the shortest half-lives) to have been experimentally verified are <a href="/facts/Rubidium-87/9jc8FbaB">87Rb</a> (4.92×1010 years), <a href="/facts/Rhenium-187/UmIoHfcT">187Re</a> (4.12×1010 years), <a href="/facts/Lutetium-176/yUu2IeCp">176Lu</a> (3.70×1010 years), <a href="/facts/Thorium-232/lRb3opzg">232Th</a> (1.41×1010 years), <a href="/facts/Uranium-238/QhcHm6q8">238U</a> (4.47×109 years), <a href="/facts/Potassium-40/RMnkrhvc">40K</a> (1.25×109 years), and <a href="/facts/Uranium-235/pe0RznDM">235U</a> (7.04×108 years). </p><p>These are the seven nuclides with half-lives comparable to, or somewhat less than, the estimated <a href="/facts/Age_of_the_universe/BaByputq">age of the universe</a>. (87Rb, 187Re, 176Lu, and 232Th have half-lives somewhat longer than the age of the universe.) For a complete list of the 35 known primordial radionuclides, including the next 28 with half-lives much longer than the age of the universe, see the complete list below. For practical purposes, nuclides with half-lives much longer than the age of the universe may be treated as if they were stable. 87Rb, 187Re, 176Lu, 232Th, and 238U have half-lives long enough that their decay is limited over geological time scales; 40K and 235U have shorter half-lives and are hence severely depleted, but are still long-lived enough to persist significantly in nature. </p><p>The longest-lived isotope not proven to be primordial<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a> is <a href="/facts/Samarium-146/e5wQw5B0">146Sm</a>, which has a half-life of 9.20×107 years, followed by <a href="/facts/Plutonium-244/XGtUVghF">244Pu</a> (8.13×107 years) and <a href="/facts/Niobium-92/nbT6c0vs">92Nb</a> (3.47×107 years). 244Pu was reported to exist in nature as a primordial nuclide in 1971,<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> but this detection could not be confirmed by further studies in 2012 and 2022.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a><a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> </p><p>Taking into account that all these nuclides must exist for at least 4.58×109 years, 146Sm must survive 50 half-lives (and hence be reduced by 250 ≈ 1×1015), 244Pu must survive 57 (and be reduced by a factor of 257 ≈ 1×1017), and 92Nb must survive 130 (and be reduced by 2130 ≈ 1×1039). Mathematically, considering the likely initial abundances of these nuclides, primordial 146Sm and 244Pu should persist somewhere within the Earth today, even if they are not identifiable in the relatively minor portion of the Earth's crust available to human assays, while 92Nb and all shorter-lived nuclides should not. Nuclides such as 92Nb that were present in the primordial solar nebula but have long since decayed away completely are termed <a href="/facts/Extinct_radionuclide/dmr9aTBW">extinct radionuclides</a> if they have no other means of being regenerated.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> As for 244Pu, calculations suggest that as of 2022, sensitivity limits were about one order of magnitude away from detecting it as a primordial nuclide.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> </p><p>Because primordial chemical elements often consist of more than one primordial isotope, there are only 83 distinct primordial <a href="/facts/Chemical_element/0jducgWD">chemical elements</a>. Of these, 80 have at least one <a href="/facts/Observationally_stable/vC0VVvqN">observationally stable</a> isotope and three additional primordial elements have only radioactive isotopes (<a href="/facts/Bismuth/75FLjkoX">bismuth</a>, <a href="/facts/Thorium/ysdWH470">thorium</a>, and uranium). </p> <h2 id="naturally-occurring-nuclides-that-are-not-primordial">Naturally occurring nuclides that are not primordial</h2> <p>Some unstable isotopes which occur naturally (such as <a href="/facts/Carbon-14/Ut8SBNNa">14C</a>, <a href="/facts/Hydrogen-3/HWSa6EHy">3H</a>, and <a href="/facts/Plutonium-239/eRobTXos">239Pu</a>) are not primordial, as they must be constantly regenerated. This occurs by <a href="/facts/Cosmic_radiation/uxCVdTKd">cosmic radiation</a> (in the case of <a href="/facts/Cosmogenic_nuclide/TlJwc4wV">cosmogenic nuclides</a> such as 14C and 3H), or (rarely) by such processes as geonuclear transmutation (<a href="/facts/Neutron_capture/elsFpM12">neutron capture</a> of uranium in the case of 237Np and 239Pu). Other examples of common naturally occurring but non-primordial nuclides are isotopes of <a href="/facts/Radon/0V9arWKl">radon</a>, <a href="/facts/Polonium/G4rzsyjP">polonium</a>, and <a href="/facts/Radium/VWo5gkzn">radium</a>, which are all <a href="/facts/Radiogenic_nuclide/KXP6MKk6">radiogenic nuclide</a> daughters of uranium decay and are found in uranium ores. The stable <a href="/facts/Argon/QX6NRH6d">argon</a> isotope 40Ar is actually more common as a radiogenic nuclide than as a primordial nuclide, forming almost 1% of the Earth's <a href="/facts/Atmosphere/oUpLaGRF">atmosphere</a>, which is regenerated by the <a href="/facts/Beta_decay/vxTBlckp">beta decay</a> of the extremely long-lived radioactive primordial isotope <a href="/facts/Potassium-40/RMnkrhvc">40K</a>, whose half-life is on the order of a billion years and thus has been generating argon since early in the Earth's existence. (Primordial argon was dominated by the <a href="/facts/Alpha_process/S8cf71rL">alpha process</a> nuclide 36Ar, which is significantly rarer than 40Ar on Earth.) </p><p>A similar radiogenic series is derived from the long-lived radioactive primordial nuclide <a href="/facts/Thorium-232/lRb3opzg">232Th</a>. These nuclides are described as geogenic, meaning that they are decay or fission products of uranium or other actinides in subsurface rocks.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> All such nuclides have shorter half-lives than their parent radioactive primordial nuclides. Some other geogenic nuclides do not occur in the <a href="/facts/Decay_chain/JvTwPNBn">decay chains</a> of 232Th, 235U, or 238U but can still fleetingly occur naturally as products of the <a href="/facts/Spontaneous_fission/0QuJoVKI">spontaneous fission</a> of one of these three long-lived nuclides, such as <a href="/facts/Tin-126/C3yupbqu">126Sn</a>, which makes up about 10−14 of all natural <a href="/facts/Tin/obW9mqc3">tin</a>.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> Another, <a href="/facts/Technetium-99/0w2EE0G2">99Tc</a>, has also been detected.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> There are five other <a href="/facts/Long-lived_fission_product/wxe6qNIp">long-lived fission products</a> known. </p> <h2 id="primordial-elements">Primordial elements</h2> <p class="note">"Primordial element" redirects here. For a concept in algebra, see <a href="/facts/Primordial_element_(algebra)/vj4KpnrY">Primordial element (algebra)</a>.</p> <p>A primordial element is a <a href="/facts/Chemical_element/0jducgWD">chemical element</a> with at least one primordial nuclide. There are 251 stable primordial nuclides and 35 radioactive primordial nuclides, but only 80 primordial stable <i>elements</i>—hydrogen through lead, atomic numbers 1 to 82, except for <a href="/facts/Technetium/MGYWNI5d">technetium</a> (43) and <a href="/facts/Promethium/8xvCz9Rg">promethium</a> (61)—and three radioactive primordial <i>elements</i>—bismuth (83), thorium (90), and uranium (92). If plutonium (94) turns out to be primordial (specifically, the long-lived isotope 244Pu), then it would be a fourth radioactive primordial, though practically speaking it would still be more convenient to produce synthetically. Bismuth's half-life is so long that it is often classed with the 80 stable elements instead, since its radioactivity is not a cause for concern. The number of elements is smaller than the number of nuclides, because many of the primordial elements are represented by multiple <a href="/facts/Isotopes/KD9B1y6o">isotopes</a>. See <a href="/facts/Chemical_element/0jducgWD">chemical element</a> for more information. </p> <h2 id="naturally-occurring-stable-nuclides">Naturally occurring stable nuclides</h2> <p>As noted, these number about 251. For a list, see the article <a href="/facts/List_of_elements_by_stability_of_isotopes/Bm0ogJmR">list of elements by stability of isotopes</a>. For a complete list noting which of the "stable" 251 nuclides may be in some respect unstable, see <a href="/facts/List_of_nuclides/RSRMmg77">list of nuclides</a> and <a href="/facts/Stable_nuclide/vC0VVvqN">stable nuclide</a>. These questions do not impact the question of whether a nuclide is primordial, since all "nearly stable" nuclides, with half-lives longer than the age of the universe, are also primordial. </p> <h2 id="radioactive-primordial-nuclides">Radioactive primordial nuclides</h2> <p>Though it is estimated that about 35 primordial nuclides are <a href="/facts/Radioactive/Ya6FVjt4">radioactive</a> (list below), it becomes very hard to determine the exact total number of radioactive primordials, because the total number of stable nuclides is uncertain. There are many extremely long-lived nuclides whose half-lives are still unknown; in fact, all nuclides heavier than <a href="/facts/Dysprosium-164/F62g1Ep8">dysprosium-164</a> are theoretically radioactive. For example, it is predicted theoretically that all <a href="/facts/Isotopes_of_tungsten/hsYx9Wbb">isotopes of tungsten</a>, including those indicated by even the most modern empirical methods to be stable, must be radioactive and can <a href="/facts/Alpha_decay/rCsHNIUE">alpha decay</a>, but as of 2013<a href="https://en.wikipedia.org/w/index.php?title=Primordial_nuclide&action=edit">[update]</a> this could only be measured experimentally for <a href="/facts/Tungsten/WYwbNDYX">180W</a>.<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> Likewise, all four primordial <a href="/facts/Isotopes_of_lead/V9JFUTRo">isotopes of lead</a> are expected to decay to <a href="/facts/Mercury_(element)/WlxfoHva">mercury</a>, but the predicted half-lives are so long (some exceeding 10100 years) that such decays could hardly be observed in the near future. Nevertheless, the number of nuclides with half-lives so long that they cannot be measured with present instruments—and are considered from this viewpoint to be <a href="/facts/Stable_nuclide/vC0VVvqN">stable nuclides</a>—is limited. Even when a "stable" nuclide is found to be radioactive, it merely moves from the <i>stable</i> to the <i>unstable</i> list of primordials, and the total number of primordial nuclides remains unchanged. For practical purposes, these nuclides may be considered stable for all purposes outside specialized research. </p> <h3>List of 35 radioactive primordial nuclides and measured half-lives</h3> <p>These 35 primordial radionuclides are isotopes of 28 elements (cadmium, neodymium, osmium, samarium, tellurium, uranium, and xenon each have two primordial radioisotopes). These nuclides are listed in order of decreasing stability. Many of them are so nearly stable that they compete for abundance with stable isotopes of their respective elements. For three elements (<a href="/facts/Indium/zRq3stVb">indium</a>, <a href="/facts/Tellurium/v7QvfIvS">tellurium</a>, and <a href="/facts/Rhenium/TzyqJYEn">rhenium</a>) a very long-lived radioactive primordial nuclide is more abundant than a stable nuclide. </p><p>The longest-lived radionuclide known, 128Te, has a half-life of 2.2×1024 years: 1.6 × 1014 times the <a href="/facts/Age_of_the_Universe/BaByputq">age of the Universe</a>. Only four of these 35 nuclides have half-lives shorter than, or equal to, the age of the universe. Most of the other 30 have half-lives much longer. The shortest-lived primordial, 235U, has a half-life of 703.8 million years, about 1/6 the age of the Earth and <a href="/facts/Formation_and_evolution_of_the_Solar_System/cgElXHpM">Solar System</a>. Many of these nuclides decay by <a href="/facts/Double_beta_decay/ILmpbfqS">double beta decay</a>, though some like 209Bi decay by other means such as <a href="/facts/Alpha_decay/rCsHNIUE">alpha decay</a>. </p><p>At the end of the list, are two more nuclides: 146Sm and 244Pu. They have not been confirmed as primordial, but their half-lives are long enough that minute quantities should persist today. </p> <table><tbody><tr><th>No.</th><th>Nuclide</th><th>Energy</th><th>Half-life(years)</th><th>Decaymode</th><th><a href="/facts/Decay_energy/g4wDGC8r">Decay energy</a>(MeV)</th><th>Approx. ratiohalf-life to<a href="/facts/Age_of_the_universe/BaByputq">age of universe</a></th></tr><tr><td>252</td><td>128Te</td><td>8.743261</td><td>2.2×1024</td><td>2 β−</td><td>2.530</td><td>160 trillion</td></tr><tr><td>253</td><td>124Xe</td><td>8.778264</td><td>1.8×1022</td><td>KK</td><td>2.864</td><td>1.3 trillion</td></tr><tr><td>254</td><td>78Kr</td><td>9.022349</td><td>9.2×1021</td><td>KK</td><td>2.846</td><td>670 billion</td></tr><tr><td>255</td><td>136Xe</td><td>8.706805</td><td>2.165×1021</td><td>2 β−</td><td>2.462</td><td>160 billion</td></tr><tr><td>256</td><td>76Ge</td><td>9.034656</td><td>1.8×1021</td><td>2 β−</td><td>2.039</td><td>130 billion</td></tr><tr><td>257</td><td>130Ba</td><td>8.742574</td><td>1.2×1021</td><td>KK</td><td>2.620</td><td>87 billion</td></tr><tr><td>258</td><td>82Se</td><td>9.017596</td><td>1.1×1020</td><td>2 β−</td><td>2.995</td><td>8.0 billion</td></tr><tr><td>259</td><td>116Cd</td><td>8.836146</td><td>3.102×1019</td><td>2 β−</td><td>2.809</td><td>2.3 billion</td></tr><tr><td>260</td><td>48Ca</td><td>8.992452</td><td>2.301×1019</td><td>2 β−</td><td>4.274, .0058</td><td>1.7 billion</td></tr><tr><td>261</td><td>209Bi</td><td>8.158689</td><td>2.01×1019</td><td>α</td><td>3.137</td><td>1.5 billion</td></tr><tr><td>262</td><td>96Zr</td><td>8.961359</td><td>2.0×1019</td><td>2 β−</td><td>3.4</td><td>1.5 billion</td></tr><tr><td>263</td><td>150Nd</td><td>8.562594</td><td>9.3×1018<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a></td><td>2 β−</td><td>3.367</td><td>671 million</td></tr><tr><td>264</td><td>130Te</td><td>8.766578</td><td>8.806×1018</td><td>2 β−</td><td>.868</td><td>640 million</td></tr><tr><td>265</td><td>100Mo</td><td>8.933167</td><td>7.07×1018<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a></td><td>2 β−</td><td>3.035</td><td>510 million</td></tr><tr><td>266</td><td>151Eu</td><td>8.565759</td><td>4.62×1018</td><td>α</td><td>1.9644</td><td>333 million</td></tr><tr><td>267</td><td>180W</td><td>8.347127</td><td>1.801×1018</td><td>α</td><td>2.509</td><td>130 million</td></tr><tr><td>268</td><td>50V</td><td>9.055759</td><td>1.4×1017</td><td>β+ or β−</td><td>2.205, 1.038</td><td>10 million</td></tr><tr><td>269</td><td>174Hf</td><td>8.392287</td><td>7.0×1016</td><td>α</td><td>2.497</td><td>5.1 million</td></tr><tr><td>270</td><td>113Cd</td><td>8.859372</td><td>7.7×1015</td><td>β−</td><td>.321</td><td>560,000</td></tr><tr><td>271</td><td>148Sm</td><td>8.607423</td><td>7.005×1015</td><td>α</td><td>1.986</td><td>510,000</td></tr><tr><td>272</td><td>144Nd</td><td>8.652947</td><td>2.292×1015</td><td>α</td><td>1.905</td><td>170,000</td></tr><tr><td>273</td><td>186Os</td><td>8.302508</td><td>2.002×1015</td><td>α</td><td>2.823</td><td>150,000</td></tr><tr><td>274</td><td>115In</td><td>8.849910</td><td>4.41×1014</td><td>β−</td><td>.499</td><td>32,000</td></tr><tr><td>275</td><td>152Gd</td><td>8.562868</td><td>1.08×1014</td><td>α</td><td>2.203</td><td>7,800</td></tr><tr><td>276</td><td>184Os</td><td>8.311850</td><td>1.12×1013</td><td>α</td><td>2.963</td><td>810</td></tr><tr><td>277</td><td>190Pt</td><td>8.267764</td><td>4.83×1011<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a></td><td>α</td><td>3.252</td><td>35</td></tr><tr><td>278</td><td>147Sm</td><td>8.610593</td><td>1.061×1011</td><td>α</td><td>2.310</td><td>7.7</td></tr><tr><td>279</td><td>138La</td><td>8.698320</td><td>1.021×1011</td><td>β− or K or β+</td><td>1.044, 1.737, 1.737</td><td>7.4</td></tr><tr><td>280</td><td>87Rb</td><td>9.043718</td><td>4.972×1010</td><td>β−</td><td>.283</td><td>3.6</td></tr><tr><td>281</td><td>187Re</td><td>8.291732</td><td>4.122×1010</td><td>β−</td><td>.0026</td><td>3.0</td></tr><tr><td>282</td><td>176Lu</td><td>8.374665</td><td>3.764×1010</td><td>β−</td><td>1.193</td><td>2.7</td></tr><tr><td>283</td><td>232Th</td><td>7.918533</td><td>1.405×1010</td><td>α or SF</td><td>4.083</td><td>1.0</td></tr><tr><td>284</td><td>238U</td><td>7.872551</td><td>4.468×109</td><td>α or SF or 2 β−</td><td>4.270</td><td>0.32</td></tr><tr><td>285</td><td>40K</td><td>8.909707</td><td>1.251×109</td><td>β− or K or β+</td><td>1.311, 1.505, 1.505</td><td>0.091</td></tr><tr><td>286</td><td>235U</td><td>7.897198</td><td>7.038×108</td><td>α or SF</td><td>4.679</td><td>0.051</td></tr><tr><td>287</td><td>146Sm</td><td>8.626136</td><td>9.20×107<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a></td><td>α</td><td>2.529</td><td>0.0067</td></tr><tr><td>288</td><td>244Pu</td><td>7.826221</td><td>8.13×107</td><td>α or SF</td><td>4.666</td><td>0.0059</td></tr></tbody></table> <h4>List legends</h4> No. (number) A running positive integer for reference. These numbers may change slightly in the future since there are 251 nuclides now classified as stable, but which are theoretically predicted to be unstable (see <a href="/facts/Stable_nuclide/vC0VVvqN">Stable nuclide § Still-unobserved decay</a>), so that future experiments may show that some are in fact unstable. The number starts at 252, to follow the 251 (observationally) stable nuclides. Nuclide Nuclide identifiers are given by their mass number <i>A</i> and the symbol for the corresponding chemical element (implies a unique <a href="/facts/Atomic_number/bgAr581S">proton number</a>). Energy Mass of the average nucleon of this nuclide relative to the mass of a neutron (so all nuclides get a positive value) in <a href="/facts/MeV/YMT1fqX9">MeV</a>/c2, formally: <i>m</i>n − <i>m</i>nuclide / <i>A</i>. Half-life All times are given in years. <a href="/facts/Radioactive_decay/Ya6FVjt4">Decay</a> mode <table><tbody><tr><td> α</td><td> <a href="/facts/Alpha_decay/rCsHNIUE">α decay</a></td></tr><tr><td> β−</td><td> <a href="/facts/Beta_decay/vxTBlckp">β− decay</a></td></tr><tr><td> K</td><td> <a href="/facts/Electron_capture/EIccoV1u">electron capture</a></td></tr><tr><td> KK</td><td> <a href="/facts/Double_electron_capture/aQ1ElH3c">double electron capture</a></td></tr><tr><td> β+</td><td> <a href="/facts/Beta_decay/vxTBlckp">β+ decay</a></td></tr><tr><td> SF</td><td> <a href="/facts/Spontaneous_fission/0QuJoVKI">spontaneous fission</a></td></tr><tr><td> 2 β−</td><td> <a href="/facts/Double_beta_decay/ILmpbfqS">double β− decay</a></td></tr><tr><td> 2 β+</td><td> <a href="/facts/Double_beta_decay/ILmpbfqS">double β+ decay</a></td></tr><tr><td> I</td><td> <a href="/facts/Nuclear_isomer/L8DHcqnk">isomeric transition</a></td></tr><tr><td> p</td><td> <a href="/facts/Proton_emission/9zxVkBkp">proton emission</a></td></tr><tr><td> n</td><td> <a href="/facts/Neutron_emission/lXLQRDCQ">neutron emission</a></td></tr></tbody></table> Decay energy Multiple values for (maximal) decay energy in <a href="/facts/Electronvolt/YMT1fqX9">MeV</a> are mapped to decay modes in their order. <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Alpha_nuclide/LGETggTY">Alpha nuclide</a></li> <li><a href="/facts/List_of_nuclides/RSRMmg77">Table of nuclides sorted by half-life</a></li> <li><a href="/facts/Table_of_nuclides/wb9TQwN7">Table of nuclides</a></li> <li><a href="/facts/Isotope_geochemistry/Pq2IXawb">Isotope geochemistry</a></li> <li><a href="/facts/Radionuclide/5WpCfbdq">Radionuclide</a></li> <li><a href="/facts/Mononuclidic_element/3hmC7IpX">Mononuclidic element</a></li> <li><a href="/facts/Monoisotopic_element/WzpKpVfg">Monoisotopic element</a></li> <li><a href="/facts/Stable_isotope/vgcdxgjA">Stable isotope</a></li> <li><a href="/facts/List_of_nuclides/RSRMmg77">List of nuclides</a></li> <li><a href="/facts/List_of_elements_by_stability_of_isotopes/Bm0ogJmR">List of elements by stability of isotopes</a></li> <li><a href="/facts/Big_Bang_nucleosynthesis/IvM4gbKH">Big Bang nucleosynthesis</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Samir Maji; et al. 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