primordial nuclei

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Primordial nuclide

Primordial element redirects here. For a concept in al-gebra, see Primordial element (algebra) .

In geochemistry and geonuclear physics , primor-

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Relative abundance of the chemical elements in the Earths upper continental crust , on a per-atom basis

dial nuclides , also known as primordial isotopes , are

nuclides found on the Earth that have existed in their cur-rent form since before Earth was formed . Primordial nu-clides are residues from the Big Bang, from cosmogenicsources , and fromancient supernova explosions which oc-curred before the formation of the solar system . They arethe stable nuclides plus the long-lived fraction of radionu-clides surviving in the primordial solar nebula throughplanet accretion until the present. Only 288 such nuclidesare known.

All of the known 254 stable nuclides occur as primor-dial nuclides, plus another 34 nuclides that have half-lives long enough to have survived from the formation

of the Earth. These 34 primordial radionuclides rep-resent isotopes of 28 separate elements . Cadmium ,tellurium , neodymium and uranium each have two pri-mordial radioisotopes ( 113Cd , 116Cd ; 128Te , 130Te ;144Nd , 150Nd ; and 235U , 238U ), and samarium hasthree ( 146Sm , 147Sm , 148Sm ).

Due to the age of the Earth of 4.5810 9 years (4.6 billionyears), this means that the half-life of the given nuclidesmust be greater than about 510 7 years (50 million years)for practical considerations. For example, for a nuclidewith half-life 610 7 years (60 million years), this means77 half-lives have elapsed, meaning that for each mole

(6.021023

atoms) of that nuclide being present at theformation of Earth, only 4 atoms remain today.

The shortest-lived primordial nuclides (i.e. nuclides with

shortest half-lives) are:

..., 232Th , 238U , 40K, 235U , 146Sm and244Pu .

These are the 6 nuclides with half-lives comparable to,or less than, the estimated age of the universe . (In thecase for 232 Th, it has a half life of more than 14 billionyears, slightly longer than the age of the universe.) For acomplete list of the 34 known primordial radionuclides ,

including the next 28 with half-lives much longer than theage of the universe, see the complete list in the sectionbelow.

The next longest-living nuclide after the end of the listgiven in the table is niobium-92 with a half-life of3.4710 7 years. (See list of nuclides for the list of allnuclides with half-lives longer than 60 minutes.) To bedetected primordially, 92 Nb would have to survive at least132 half-lives since the Earths formation, meaning itsoriginal concentration will have decreased by a factor of10 40 . As of 2013, it has not been detected. It has beenfound that the next longer-lived nuclide, 244Pu , with a

half-life of 8.08107

years is primordial, although justbarely, as its concentration in a few ores is nearly 10 18

weight parts. [1][2] Taking into account that all these nu-clides must exist since at least 4.610 9 years, meaningsurvive 57 half-lives, their original number is now re-duced by a factor of 2 57 which equals more than 10 17 .[3]

Although it is estimated that about 34 primordial nuclidesare radioactive (list below), it becomes very difficult todetermine the exact total number of radioactive primor-dials, because the total number of stable nuclides is un-certain. There exist many extremely long-lived nuclideswhose half-lives are still unknown. For example, it is

known theoretically that all isotopes of tungsten , includ-ing those indicated by even the most modern empiricalmethods to be stable, must be radioactive and can de-cay by alpha emission , but as of 2013 this could onlybe measured experimentally for 180W .[4] Nevertheless,the number of nuclides with half-lives so long that theycannot be measured with present instrumentsand areconsidered from this viewpoint to be stable nuclides islimited. Even when a stable nuclide is found to be ra-dioactive, the fact merely moves it from the stable to theunstable list of primordial nuclides, and the total numberof primordial nuclides remains unchanged.

Because primordial chemical elements often consist ofmore than one primordial isotope, there are only 84 dis-tinct primordial chemical elements . Of these, 80 have

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https://en.wikipedia.org/wiki/Nuclidehttps://en.wikipedia.org/wiki/Nuclidehttps://en.wikipedia.org/wiki/Accretion_(astrophysics)https://en.wikipedia.org/wiki/Earthhttps://en.wikipedia.org/wiki/Mole_(unit)https://en.wikipedia.org/wiki/Formation_of_the_Earthhttps://en.wikipedia.org/wiki/Tungstenhttps://en.wikipedia.org/wiki/Chemical_elementhttps://en.wikipedia.org/wiki/Stable_nuclideshttps://en.wikipedia.org/wiki/Tungsten-180https://en.wikipedia.org/wiki/Alpha_emissionhttps://en.wikipedia.org/wiki/Tungstenhttps://en.wikipedia.org/wiki/Isotopehttps://en.wikipedia.org/wiki/Radioactivehttps://en.wikipedia.org/wiki/Plutonium-244https://en.wikipedia.org/wiki/Niobiumhttps://en.wikipedia.org/wiki/List_of_nuclideshttps://en.wikipedia.org/wiki/Isotopes_of_niobiumhttps://en.wikipedia.org/wiki/Radionuclideshttps://en.wikipedia.org/wiki/Age_of_the_universehttps://en.wikipedia.org/wiki/Plutonium-244https://en.wikipedia.org/wiki/Samarium-146https://en.wikipedia.org/wiki/Uranium-235https://en.wikipedia.org/wiki/Potassium-40https://en.wikipedia.org/wiki/Uranium-238https://en.wikipedia.org/wiki/Thorium-232https://en.wikipedia.org/wiki/Mole_(unit)https://en.wikipedia.org/wiki/Half-lifehttps://en.wikipedia.org/wiki/Age_of_the_Earthhttps://en.wikipedia.org/wiki/Samarium-148https://en.wikipedia.org/wiki/Samarium-147https://en.wikipedia.org/wiki/Samarium-146https://en.wikipedia.org/wiki/Samariumhttps://en.wikipedia.org/wiki/Uranium-238https://en.wikipedia.org/wiki/Uranium-235https://en.wikipedia.org/wiki/Neodymium-150https://en.wikipedia.org/wiki/Neodymium-144https://en.wikipedia.org/wiki/Tellurium-130https://en.wikipedia.org/wiki/Tellurium-128https://en.wikipedia.org/wiki/Cadmium-116https://en.wikipedia.org/wiki/Cadmium-113https://en.wikipedia.org/wiki/Uraniumhttps://en.wikipedia.org/wiki/Neodymiumhttps://en.wikipedia.org/wiki/Telluriumhttps://en.wikipedia.org/wiki/Cadmiumhttps://en.wikipedia.org/wiki/Chemical_elementhttps://en.wikipedia.org/wiki/Isotopehttps://en.wikipedia.org/wiki/Half-lifehttps://en.wikipedia.org/wiki/Half-lifehttps://en.wikipedia.org/wiki/Stable_nuclidehttps://en.wikipedia.org/wiki/Accretion_(astrophysics)https://en.wikipedia.org/wiki/Solar_systemhttps://en.wikipedia.org/wiki/Supernova_nucleosynthesishttps://en.wikipedia.org/wiki/Cosmogenic_nuclidehttps://en.wikipedia.org/wiki/Cosmogenic_nuclidehttps://en.wikipedia.org/wiki/Big_Banghttps://en.wikipedia.org/wiki/Formation_of_the_Earthhttps://en.wikipedia.org/wiki/Earthhttps://en.wikipedia.org/wiki/Nuclidehttps://en.wikipedia.org/wiki/Crust_(geology)https://en.wikipedia.org/wiki/Nuclear_physicshttps://en.wikipedia.org/wiki/Geochemistryhttps://en.wikipedia.org/wiki/Primordial_element_(algebra)


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2 4 LIST OF 34 RADIOACTIVE PRIMORDIAL NUCLIDES AND MEASURED HALF-LIVES

at least one observationally stable isotope and four addi-tional primordial elements have only radioactive isotopes.

1 Naturally occurring nuclides thatare not primordial

Some unstable isotopes which occur naturally (such as14C , 3H, and 239Pu ) are not primordial, as they mustbe constantly regenerated. This occurs by cosmic radia-tion (in the case of cosmogenic nuclides such as 14C and3H), or (rarely) by such processes as geonuclear transmu-tation ( neutron capture of uranium in the case of 239Pu).Other examples of common naturally-occurring but non-primordial nuclides are radon , polonium , and radium ,which are all radiogenic nuclide daughters of uraniumdecay and are found in uranium ores. A similar radio-genic series is derived from the long-lived radioactive pri-mordial nuclide thorium-232 . All of such nuclides haveshorter half-lives than their parent radioactive primordialnuclides.

There are about 51 nuclides which are radioactive andexist naturally on Earth but are not primordial (making atotal of fewer than 340 total nuclides to be found naturallyon Earth).

2 Primordial elements

There are 254 stable primordial nuclides and 34 radioac-tive primordial nuclides, but only 80 primordial stable el-ements (1 through 82, i.e. hydrogen through lead, exclu-sive of 43 and 61, technetium and promethium respec-tively) and four radioactive primordial elements (bismuth,thorium, uranium, and plutonium). The numbers of ele-ments are smaller, because many primordial elements arerepresented by more than one primordial nuclide. Seechemical element for more information.

3 Naturally occurring stable nu-clides

As noted, these number about 254. For a list, see thearticle list of stable isotopes . For a complete list notingwhich of thestable 254 nuclides may be in some respectunstable, see list of nuclides and stable isotope . Thesequestions 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 primordialalso.

4 List of 34 radioactive primordialnuclides and measured half-lives

These 34 primordial nuclides represent radioisotopes of28 distinct chemical elements (cadmium, neodymium,

tellurium, and uranium each have two primordial ra-dioisotopes, and samarium has three). The radionuclidesare listed in order of stability, with the longest half-lifebeginning the list. These radionuclides in many cases areso nearly stable that they compete for abundance withstable isotopes of their respective elements. For threechemical elements, a very long lived radioactive primor-dial nuclide is found to be the most abundant nuclide foran element that also has a stable nuclide. These unusualelements are tellurium , indium , and rhenium .

The longest has a half-life of 2.210 24 years, which is160 million million times the age of the Universe (the

latter is about 4.321017

s). Only six of these 34 nuclideshave half-lives shorter than, or equal to, the age of theuniverse. Most of the remaining 28 have half-lives muchlonger. The shortest-lived primordial isotope has a half-life of only 80 million years, less than 2% of the age ofthe Earth and Solar System .

4.1 List legends

no (number)

A running positive integer for reference. These num-bers may change slightly in the future since there are 164nuclides now classied as stable, but which are theoret-ically predicted to be unstable (see Stable nuclide#Still-unobserved decay ), so that future experiments may showthat some are in fact unstable. The number starts at 255,to follow the 254 nuclides (or stable isotopes ) not yetfound to be radioactive.

nuclide column

Nuclide identiers are given by their mass number A andthe symbol for the corresponding chemical element (im-plies a unique proton number).

energy column

The column labeled energy denotes the mass of the av-erage nucleon of this nuclide relative to the mass of aneutron (so all nuclides get a positive value) in MeV , for-mally: m m / A.

half-life column

All times are given in years

decay mode column
https://en.wikipedia.org/wiki/Radioactive_decayhttps://en.wikipedia.org/wiki/MeVhttps://en.wikipedia.org/wiki/Stable_isotopehttps://en.wikipedia.org/wiki/Stable_nuclide#Still-unobserved_decayhttps://en.wikipedia.org/wiki/Stable_nuclide#Still-unobserved_decayhttps://en.wikipedia.org/wiki/Age_of_the_Solar_Systemhttps://en.wikipedia.org/wiki/Age_of_the_Universehttps://en.wikipedia.org/wiki/Rheniumhttps://en.wikipedia.org/wiki/Indiumhttps://en.wikipedia.org/wiki/Telluriumhttps://en.wikipedia.org/wiki/Stable_isotopehttps://en.wikipedia.org/wiki/List_of_nuclideshttps://en.wikipedia.org/wiki/List_of_stable_isotopeshttps://en.wikipedia.org/wiki/Chemical_elementhttps://en.wikipedia.org/wiki/Promethiumhttps://en.wikipedia.org/wiki/Technetiumhttps://en.wikipedia.org/wiki/Thorium-232https://en.wikipedia.org/wiki/Radiogenic_nuclidehttps://en.wikipedia.org/wiki/Radiumhttps://en.wikipedia.org/wiki/Poloniumhttps://en.wikipedia.org/wiki/Radonhttps://en.wikipedia.org/wiki/Neutron_capturehttps://en.wikipedia.org/wiki/Cosmogenic_nuclidehttps://en.wikipedia.org/wiki/Cosmic_radiationhttps://en.wikipedia.org/wiki/Cosmic_radiationhttps://en.wikipedia.org/wiki/Plutonium-239https://en.wikipedia.org/wiki/Hydrogen-3https://en.wikipedia.org/wiki/Carbon-14https://en.wikipedia.org/wiki/Observationally_stable


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decay energy column

Multiple values for (maximal) decay energy in MeV aremapped to decay modes in their order.

5 See also

Table of nuclides sorted by half-life

Table of nuclides

Isotope geochemistry

Radionuclide

Mononuclidic element

Monoisotopic element

Stable isotope

List of nuclides

List of elements by stability of isotopes

List of elements by nuclear stability

Big Bang nucleosynthesis

6 References

[1] D.C. Hoffman, F.O. Lawrence, J.L. Mewherter,F.M. Rourke (1971). Detection of Plutonium-244 in Nature. Nature 234 (5325): 132134.Bibcode :1971Natur.234..132H . doi:10.1038/234132a0 .

[2] S. Maji, S. Lahiri, B. Wierczinski, G. Korschinek (2006).Separation of samarium and neodymium: a prerequi-site for getting signals from nuclear synthesis. Analyst 131 (12): 13321334. Bibcode :2006Ana...131.1332M .doi:10.1039/b608157f . PMID 17124541 .

[3] P.K. Kuroda (1979). Origin of the elements: pre-Fermireactor and plutonium-244 in nature. Accounts of Chem-ical Research 12 (2): 7378. doi :10.1021/ar50134a005 .

[4] Interactive Chart of Nuclides (Nudat2.5)" . National Nu-clear Data Center . Retrieved 2009-06-22.
https://en.wikipedia.org/wiki/National_Nuclear_Data_Centerhttps://en.wikipedia.org/wiki/National_Nuclear_Data_Centerhttp://www.nndc.bnl.gov/nudat2/http://dx.doi.org/10.1021%252Far50134a005https://en.wikipedia.org/wiki/Digital_object_identifierhttps://en.wikipedia.org/wiki/Accounts_of_Chemical_Researchhttps://en.wikipedia.org/wiki/Accounts_of_Chemical_Researchhttps://www.ncbi.nlm.nih.gov/pubmed/17124541https://en.wikipedia.org/wiki/PubMed_Identifierhttp://dx.doi.org/10.1039%252Fb608157fhttps://en.wikipedia.org/wiki/Digital_object_identifierhttp://adsabs.harvard.edu/abs/2006Ana...131.1332Mhttps://en.wikipedia.org/wiki/Bibcodehttps://en.wikipedia.org/wiki/Analyst_(journal)http://dx.doi.org/10.1038%252F234132a0https://en.wikipedia.org/wiki/Digital_object_identifierhttp://adsabs.harvard.edu/abs/1971Natur.234..132Hhttps://en.wikipedia.org/wiki/Bibcodehttps://en.wikipedia.org/wiki/Nature_(journal)https://en.wikipedia.org/wiki/Big_Bang_nucleosynthesishttps://en.wikipedia.org/wiki/List_of_elements_by_nuclear_stabilityhttps://en.wikipedia.org/wiki/List_of_elements_by_stability_of_isotopeshttps://en.wikipedia.org/wiki/List_of_nuclideshttps://en.wikipedia.org/wiki/Stable_isotopehttps://en.wikipedia.org/wiki/Monoisotopic_elementhttps://en.wikipedia.org/wiki/Mononuclidic_elementhttps://en.wikipedia.org/wiki/Radionuclidehttps://en.wikipedia.org/wiki/Isotope_geochemistryhttps://en.wikipedia.org/wiki/Table_of_nuclideshttps://en.wikipedia.org/wiki/List_of_nuclideshttps://en.wikipedia.org/wiki/MeV


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4 7 TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES

7 Text and image sources, contributors, and licenses

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