Talk:Primordial nuclide

Proposed merge of primordial element to here
Primordial element is a stub, and contains no info that that isn't here (at least that I can see). I propose it be deleted and any info in it that isn't here, moved to here, if any), and replaced with a redirect that directs primordial element to THIS article. Comments? S  B Harris 21:02, 15 February 2011 (UTC)
 * Hello, anybody out there? If there are no objections, I'll do the merger as above, in a week or so. S  B Harris 02:38, 1 April 2011 (UTC)

Without the use of the adverb "why", this article is evidently an effort by somebody to talk about 33 isotopes that somebody has decreed that were created in the early stages of the stellar mass accumulation process. And for this reason it is desired to be able to add these isotopes to a different list of 255 isotopes that have been deemed to be evolutionally stable. And to understand this we are to understand the significance of a mix of halflife values which include exponential years and exponential seconds. (note that a year is 10^7.499+ or say 10^7.5 seconds). And included in this list are a number of isotopes that have had a type of decay wherein they have fallen back in the nuclide chart by 2 elements due to alpha emission, as evidenced by OE83Bi209, which is supposed to be decaying back to OE81Tl205 with a halflife of 1.9E^19years (=10^26.78seconds), which takes it out of the stable elements list. And in the chart we note that most of them are heavy isotopes, except for EE62Sm146 (1.03x 10^8years) and EO19K40 (1.248x10^9years), with the 19K40 potassium being the exception in falling (Znumber) forward to stable EE20Ca40, And thus all of these involve what might be called minor adjustments of the nuclear structure. So I guess that what we have learned is that whatever amount of any of these isotopes that is found on earth is determined to have existed before the time of accumulation of the matter of the earth. And I always wanted to know the reason for the atom of EE62Sm146 to be unstable, and now I guess I know! Note that EE62Sm146 is unique in that it is shown to be unstable in spite of the fact that 3 percent of the constituency of stable 62Sm isotopes are EE62Sm144 (with 20 extra neutrons), and in every other instance the addition of 2 more neutrons to the lightest nuclide of a multiple stable isotope element, the result is the existence of a new stable isotope with increased constituency.WFPM (talk) 04:17, 14 April 2011 (UTC)Note that in the Nubase data the mass excess value for 62Sm146 is lower than that of the reported stable 60Nd146, so they don't explain it either.
 * No, these are not some random 33 elements. They are all radioactives EXCEPT those with half lives so short, that they've decayed to undetectable levels since Earth formed (or technically since the supernova that made them contributed them to the interstellar dust and gas out of which the solar system condensed, but many supernovas are though to be involved, and it's only an extra couple of billion years over 4.5 to get them in, so the time only goes up 20%). See the full list at list of elements. S  B Harris 18:38, 14 April 2011 (UTC)

Of course not random!! That's why I've been scrounging around in the information trying to find where nature found enough neutrons near each other such as to be able to make them. But given that existence, it is probable that nature in the crunch process made some of everything and then the structural random failure rate characteristics  then sorted out the stable and long lived isotopes from the others. But most of them are heavy, and an alpha emission for a heavy isotope is no big deal. What bothers me is the opinion of science pros that they are all identical, particularly the big ones. That could foul up the statistics. So how do they know that maybe some portion of the remaining ones couldn't be stable, like EE62Sm148 and EE62Sm146, and that the rest have a slightly higher random failure rate?WFPM (talk) 23:20, 14 April 2011 (UTC)

Table is only sorting numbers by the first numeric part, even in the columns that are in exponential notation, or tagged in millions. — Preceding unsigned comment added by 171.64.58.194 (talk) 23:20, 28 July 2011 (UTC)

Note to myself to remove Te-123, which is actually observationally stable
This isotope had been observed to decay by EC, but this could not be confirmed, and although it is predicted to decay with very long half life, it is presently observationally stable. So should be removed from this list when I find good references for all that. That gives only 34 radioactive primordial nuclides. S B Harris 03:56, 6 September 2013 (UTC)

Cite: New limits on naturally occurring electron capture of 123Te full paper on arXive URL: DOI: 10.1103/PhysRevC.67.014323.

half life in years
a column with half life in years would be useful, it's a more useful unit than quadrillions of seconds or 'times 13.8 billion years' — Preceding unsigned comment added by 84.198.53.190 (talk) 21:06, 14 September 2013 (UTC)
 * Yes, I agree. Most people express long times in years (or billions of years) rather than in seconds or in universe lifetimes, so the values in years should be given. Also the universe lifetime unit suffers from the disadvantage of being uncertain; if a new measurement next year changes the accepted universe lifetime by 5%, then all our values in this unit will be off by 5%. We could delete this column and just mention the universe lifetime value in the accompanying text for comparison. Dirac66 (talk) 23:59, 14 September 2013 (UTC)
 * If you're looking to get rid of a column I'd vote to replace the half life in seconds column with one in years (and would have done so already except I don't want to do the math). All numbers with exponents this large are equally non-unwieldy anyway (what's the word I want-- non-intuitive?). In other words, within these exponent ranges a second conveys information equally as well as a year, to me. As to the ratio with the age of the universe, I find that more interesting at least on the low end. You can't measure abundance of radioactive atoms where their half life is less than about 1/160th the age of the universe, or more than 160 half lives have passed. That is a fairly small and interesting number. At the high end I find it interesting how many more times than the age of the universe these half lives are. If that wasn't a number calculated for you here, you'd be tempted to calculate it yourself, would you not? That's my criterion for a table column. S  B Harris 01:54, 16 September 2013 (UTC)
 * OK, replace the seconds column with a years column then, so that the half-lives in years are available. No need to do the math though, because the source NuDat (and also NuBase) values are given in years for long-lived isotopes. Someone just has to look up the values again. Dirac66 (talk) 02:17, 16 September 2013 (UTC)
 * Done. I noticed we already had the half-lives in years at List of nuclides, so I just used those values without checking all the conversions or the sources. Some values may be slightly different if the half-life in years is from a different source.
 * For 130Ba, however, there was a clear error which is now corrected. This article had 2.2 x 1021 sec, and List of nuclides had 1.2 x 1021 years, in rough agreement with NuDat 2.7 x 1021 years. Presumably the value in this article was really the value in years from another source, and not a value in seconds like the rest of the table. This correction moved 130Ba from no.276 to no.258. Dirac66 (talk) 01:17, 10 February 2014 (UTC)

Technical tag
I've tagged this article as being too technical because it appears to have been written by a scientist for other scientists, not for a general audience. For example, the general reader will not be familiar with scientific notation, is unlikely to be familiar with chemical symbols (particularly for elements such as samarium and thorium), and some of the vocabulary could be made more accessible via explanations. I've added in some year values for scientific notation near the start, but this article probably needs rewriting with accessibility in mind. --Poppy Appletree (talk) 14:29, 16 November 2013 (UTC)
 * You've going to have fun with that tag in the math articles. Lie algebra, anyone? After due consideration I removed the tag. This is not the place to explain scientific notation. It's really also not the place to explain chemical isotope notation, either. But this part is hyperlinked, and all of the nuclides with superscript notation are explained when you do a mouse-over. That's the joy of a hyperlinked encyclopedia. You don't have to quite start at the stone age for every science concept. S  B Harris 05:03, 10 February 2014 (UTC)

Pu-244 and Sm-146
The former's status as primordial is disputed, and the latter is much more often cited as an extinct radionuclide. Indeed, the former is considered (along with Fe-60, Hf-182, and Cm-247) as one of the extinct radionuclides for which conclusive proof of their past existence on Earth would be experimental proof that the r-process occurs in supernovae. Double sharp (talk) 12:12, 14 July 2016 (UTC)
 * More about 182Hf, 129I, 244Pu, and 247Cm. Double sharp (talk) 12:17, 14 July 2016 (UTC)

Mismatch in number of nuclides
At the end of the first paragraph it states; "Only 288 such nuclides are known". Then, the second paragraph begins as "All of the known 254 stable nuclides occur as primordial nuclides, plus another 32 nuclides that [...]". So, 254 + 32 = 286, not 288. I think the error started with this this edition, lowering the 34 to 32, but without changing 288 into 286, so I will make this change. However, it would be good having a source to avoid original research. Eynar Oxartum (talk) 16:25, 19 October 2016 (UTC)
 * Yes, the source is in the previous section, when I removed 244Pu and 146Sm: their status as primordial is at best disputed (and no one else seems to have actually written of 146Sm as primordial, to the best of my checking). Double sharp (talk) 01:59, 22 October 2016 (UTC)

Rb-87
Isn´t rubidium-87 a primordial nuclide too? — Preceding unsigned comment added by 130.237.84.46 (talk) 11:03, 6 December 2017 (UTC)


 * Yes, and it is already on the list in this article as number 280. Dirac66 (talk) 16:38, 6 December 2017 (UTC)

Naturally occurring nuclides that are not primordial: Problematic recent edits.


Two recent (24 Jan 2018) edits in the section Naturally occurring nuclides that are not primordial seem rather problematic. First the sentence There are about 51 nuclides which are radioactive and exist naturally on Earth but are not primordial (making a total of fewer than 340 total nuclides to be found naturally on Earth). was deleted with the edit summary this neglects spontaneous fission of natural thorium and uranium plus cosmogenic isotopes. The deleted fact does seem of interest, so I wonder whether the stated problem makse the sentence so valueless that it has to be deleted completely? Is it not possible for a knowledgeable editor to revise the sentence to make it more complete and/or more accurate?

And the next edit is the addition of the sentence Some other nuclides do not occur in the decay chains of 232Th, 235U, and 238U yet can still fleetingly occur naturally as products of their spontaneous fission. Of interest I agree, but it would be better to add a specific exxample or two to make it more concrete. Dirac66 (talk) 22:45, 28 January 2018 (UTC)
 * The trouble is that there are an awful lot of such geogenic isotopes, because SF of 232Th, 235U, and 238U produces variable products, and their fission (and alpha decay when those alphas strike a nearby light nucleus) releases neutrons and causes spallation, generating even more nuclides. I have not found a precise count of all of these but there must be a great deal of them, most with such fleeting occurrence that it's not terribly sensible to count them. (And the same might be said of rare branches in the radioactive decay chains of these primordials, like those leading to 206Hg or 209Pb; yes, they must be natural, but they are less substantial than even 219At.) I think it is more useful to just say that there are many such geogenic nuclides and then list some that actually occur significantly, like 36Cl or 226Ra. Double sharp (talk) 23:53, 28 January 2018 (UTC)
 * OK, I would say go ahead and mention geogenic nuclides with some examples but without trying to count the total. We do not have an article on Geogenic nuclides to link to, but the word is defined in Wiktionary at https://en.wiktionary.org/wiki/geogenic. Dirac66 (talk) 02:16, 31 January 2018 (UTC)
 * OK, will do! ^_^ Double sharp (talk) 10:24, 6 February 2018 (UTC)
 * OK, I've mentioned the term and used 126Sn as an example. This seems to be a much better example than the stable 127I, since there are traces of 126Sn still around and there is no way to make that nuclide other than as a fission product today. (The r-process would have done it, but it has a short half-life, so all of that is gone; and while a weak r-process "rain" from supernovae is sufficient to leave an equilibrium amount of 244Pu on Earth, it's not going to work for anything less long-lived.) In most other cases except Kr and Xe isotopes there is a real problem finding the SF products of natural U and tracing them to their parent in secular equilibrium, because they get swamped by the primordial isotopes of the same element, which often overlap with the fission products.) Double sharp (talk) 14:50, 6 February 2018 (UTC)
 * OK, I think the section is much better now. Thank you. Dirac66 (talk) 22:32, 7 February 2018 (UTC)

P.S. I have now realized that the article did not really define "geogenic" except for a link to Wiktionary. However Double Sharp has provided a better source in the above reply dated 28 January 2018, so I have today added that source to the article. Dirac66 (talk) 14:44, 13 July 2020 (UTC)

Wrong reference
The reference [1] states existing of primordial element heavier than U https://www.nature.com/articles/234132a0.pdf, which contradicts with the text. The right reference is https://journals.aps.org/prc/abstract/10.1103/PhysRevC.85.015801, which disproves the ref. [1] — Preceding unsigned comment added by 193.232.69.1 (talk) 10:55, 2 December 2019 (UTC)
 * Yes, the first one only supports its initial detection. I added the second one at the end of the sentence (after although later studies could not detect it) and relocated the first. Thank you for pointing this out. ComplexRational (talk) 21:03, 2 December 2019 (UTC)

Pu-244 found in oceans
In May 2021, papers confirmed that Pu-244 had been found in the Earth's oceans, alongside radioactive iron-60. (Also reported in [https://scitechdaily.com/alien-radioactive-element-discovered-in-the-ocean-crust/ Sci-Tech Daily.)

“60Fe and 244Pu deposited on Earth constrain the r-process yields of recent nearby supernovae” by A. Wallner, M. B. Froehlich, M. A. C. Hotchkis, N. Kinoshita, M. Paul, M. Martschini, S. Pavetich, S. G. Tims, N. Kivel, D. Schumann, M. Honda, H. Matsuzaki and T. Yamagata, 14 May 2021, Science. DOI: 10.1126/science.aax3972

“Trace seabed plutonium points to stellar forges of heavy elements” by Daniel Clery, 13 May 2021, Science. DOI: 10.1126/science.abj4596

Twang (talk) 05:40, 21 May 2021 (UTC)

Half-life of 190Pt is highly controversy
It can be 3.9×1011 years, 4.68×1011 years or 4.97×1011 years (see page 67). NUBASE2020 gave an average of 4.83×1011 years as result, but this means that the value itself is absolutely incorrect. 129.104.241.214 (talk) 23:04, 18 February 2024 (UTC)