Talk:Stable nuclide

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page move was carried outRadiogenic (talk) 02:25, 25 September 2013 (UTC)


How many stable isotopes are there? what percentage of all mass do they take up in:

  • earth
  • the sun
  • the universe?

cheers, mastodon 23:45, 29 December 2005 (UTC)

Merge discussion[edit]

  • Support; the reader would benefit if the content were merged. The resulting article would still be fairly short. Walter Siegmund (talk) 18:50, 26 July 2006 (UTC)
  • Agreed I would much prefer the list to be part of this page, where I would expect to find it if I was afetr information about stable isotopes. I doubt that many users would start by searching for List of.... Emeraude 09:20, 22 October 2006 (UTC)
  • Support List of stable isotopes should be placed in this article, rather than the other way around. shoy 22:21, 9 November 2006 (UTC)
  • Neutral Not a particularly terrible list to have around. Both the list an article are fairly short, and the article can be expanded upon. I don't see any particular reason to merge. i kan reed 20:49, 8 December 2006 (UTC)


It seems that the stable isotopes of C,H,O,N, and maybe a few others (S?) have so many useful applications, from determining the source of the carbon in the testosterone in Floyd Landis's bloodstream, to the water use efficiency of plants... that there is room for content on these subjects separate from the list of all known stable isotopes.

Anyone up to the challenge of writing about it all?

—The preceding unsigned comment was added by (talkcontribs) 01:15, 3 August 2006.

Topic merged. 22:45, 11 December 2006 (UTC)

Group of Stable Isotopes[edit]

Removed pointless table. The formatting was off - Be, F, ... appeared under the zero heading (or halfway between it and one). Is this just a bit of counting WP:OR? It will need some justification (double meaning there) if it is to be included. Vsmith 15:09, 16 September 2007 (UTC)


Xenon has only 7 stable isotopes.
Xenon-136 is unstable.

please fix the list it ! —Preceding unsigned comment added by (talk) 08:32, 17 September 2007 (UTC)

Not yet. Only lower limit on half-life exists. All 9 naturally occurring isotopes of Xe are not observed to be radioactive. --V1adis1av 14:17, 18 September 2007 (UTC)

You right, sorry. anyway....

Xenon-124 is missing from the list !!!!!

also Tantalum-180-m like Bismuth-209 , it's considered unstable. it's still on the list ??? !!! —Preceding unsigned comment added by (talk) 00:18, 22 September 2007 (UTC)

You are right, Xe-124 was missing. However, Ta-180m was NOT ever observed to be radioactive, only lower limits on its half life were set (technically, it can decay by four different ways: alpha, beta-minus, beta-plus and isomeric transition). So it should remain in the list until its radioactivity would be found in an experiment - I hope it will happen one day. --V1adis1av 18:54, 22 September 2007 (UTC)

Missing Isotopes[edit]

Isotopes that I noticed were missing: Chromium-50, Germanium-76, Selenium-82, Krypton-78, Molybdenum-100, Cadmium-116, Tellurium-120, Tellurium-128, Barium-130, Cerium-136, Cerium-142, Neodymium-150, Europium-151, Tungsten-180, Osmium-184, Mercury-196, Bismuth-209

Not sure about the following since in the CRC it mentions isomers: Cadmium-113, Tellurium-125, Lead-204

Istopes that need to be removed: Tellurium-123 and Tantalum-180m

I used the CRC and a comparison to the Mad_Chemist list to look for differences otherwise there is no way I would have gone throught the whole list. —Preceding unsigned comment added by (talk) 16:54, 19 February 2008 (UTC)

Among the naturally occurring (stable and long-lived) nuclides:
  • 48-Ca, 76-Ge, 82-Se, 96-Zr, 100-Mo, 116-Cd, 128-Te, 130-Te, 130-Ba, 144-Nd, and 150-Nd are double beta (2b) active;
  • 151-Eu and 180-W are alpha active;
  • 78-Kr, 123-Te, 142-Ce, 156-Dy, 149-Sm, 192-Os, and 204-Pb are not radioactive (claims on registration of radioactivity were later carefully checked and "closed", as, for example, for 123-Te). For their half lives, only lower limits are known. So them should be considered as stable, for the current experimental sensitivity.
  • 180-Ta ground state is short-lived (8.125 h) and its excited state is (meta)stable with only lower limit on the half-live known (>1e15 yr).
Let me give a list of 31 nuclides that are known to be radioactive with half-life >7E8 yr (i.e. primordial radioactive nuclides) as for today (decay modes: alpha (a), beta (b), double beta (2b), spontaneous fusion (SF), cluster emission(CE)):
40-K (b), 48-Ca (2b), 50-V (b), 76-Ge (2b), 82-Se (2b), 87-Rb (b), 96-Zr (2b), 100-Mo (2b), 113-Cd (b), 116-Cd (2b), 115-In (b), 128-Te (2b), 130-Te (2b), 130-Ba (2b), 138-La (b), 144-Nd (a), 150-Nd (2b), 147-Sm (a), 148-Sm (a), 151-Eu (a), 152-Gd (a), 176-Lu (b), 174-Hf (a), 180-W (a), 187-Re (b), 186-Os (a), 190-Pt (a), 209-Bi (a), 232-Th (a, SF), 235-U (a, CE), 238-U (a, 2b, SF).
The sources like CRC and Mad_Chemist can be out of date because many of the above-mentioned nuclides were found to be radioactive only during the last decade (for example, observation of Eu-151 alpha decay was published in 2007). For some nuclides, the lower limits established for half-lives were cited in some sources as positive results (i.e. the claims that a decay was not found and its half-life is longer than ... were understood as the half-life is equal to ...).
You are right about 50-Cr, 78-Kr, 136-Ce, 142-Ce, 196-Hg -- they have to be added to the list of stable nuclides. All of them were predicted to be double beta active (with very long half-lives) but their radioactivity was never observed. --V1adis1av (talk) 00:03, 21 February 2008 (UTC)
According to Isotopes of lead, 204-Pb is stable, too. —Preceding unsigned comment added by (talk) 20:00, 13 May 2008 (UTC)

Differences from reference[edit]

I have compared the current article list [1] to the current content of the article reference "WWW Table of Radioactive Isotopes". .
I am just reporting the differences here without evaluating them, which I haven't done any research for. The article has nine entries not in the reference:

Chromium-50, Zinc-70, Tellurium-123, Xenon-124, Xenon-136, Cerium-142, Tantalum-180m, Tungsten-183, and Tungsten-184.

The reference has eight stable entries not in the article:

76Ge, 116Cd, 120Te, 125Te, 130Ba, 151Eu, 180W, 209Bi.

PrimeHunter (talk) 00:17, 12 April 2008 (UTC)

Try to search in this mode: [2]. You can see that there are stable isotopes as well as isotopes with half-life shown like greater than 1.8E+17 y etc. It means that the radioactivity for given nuclide was not found and it should be considered as stable. Take into account that this database is somewhat old (February 1999) and studies in the last decade are not reflected. --V1adis1av (talk) 17:48, 13 January 2009 (UTC)

No stability beyond holmium?[edit]

If I understand the list right and all isotopes of elements Holmium (Ho) and beyond are really predicted seriously to be radioactive, then we should write that in other articles. Or are those modes only theoretical decays what would happen if this isotope would be unstable? then we should delete them. If Dysprosium (which is far away from Bismuth) was the last really stable element, then we would have to write that in several other articles! Because after Dy there come some common elements (W, Pt, Au, Hg, Pb) which would then be called "radioactive". Especially for gold, this is shocking if it decays to less valuable Iridium and then Re, Ta, Lu, Tm, Ho, tb so, admittedly on an extremely long run, all gold will become terbium (Tb)which we should write in the articles if verifiable! --Eu-151 (talk) 18:09, 28 June 2009 (UTC)

It's perfectly fine to reference the theoretical prediction in this article. However, because reality doesn't always follow theory, and because of the very problem you're addressing, we've taken the somewhat more conservative view that isotopes are deemed "stable" unless they have been experimentally proven to be radioactive (by direct observation of decay) or else (in the famous case of tellurium-128) by confirmation of a radiogenic daughter (which gets us out to 10^24 yrs). SBHarris 19:23, 28 June 2009 (UTC)
It would be fine "to reference the theoretical prediction in this article", but no reference for the predictions is given, AFAICS. The category "theoretically unstable" should be removed unless a reliable reference is provided. (Also, their predicted probability of decay should be vastly higher than that of proton decay for that category to make sense.) --Roentgenium111 (talk) 18:00, 30 June 2012 (UTC)
It's not really that gold-197 is "radioactive". It is created a decay chain with alpha and beta minus decay, the decay chain will end at gadolinium-157.Cristiano Toàn (talk) 03:07, 15 January 2011 (UTC)
The above remark is extremely unclear and it is practically useless. (talk) 17:09, 11 August 2012 (UTC)
The predicted decay chain of Au-197 would be:
Au-197 → Ir-193 → Re-189 → Os-189 → W-185 → Re-185 → Ta-181 → Lu-177 → Hf-177 → Yb-173 → Er-169 → Tm-169 → Ho-165 → Tb-161 → Dy-161 → Gd-157 → spontaneous fission. Double sharp (talk) 15:10, 29 September 2012 (UTC)

Gold-197 is predict to be undergone by alpha decay because gold-197 nuclide has a slightly heavier than sum of masses of alpha particle and Iridium-197 nuclide Each Gold-197 atom has a mass 196.9665687u Iridium-193 atom has a mass 192.9629264u Alpha partilce 4.0026025u Each gold-197 atom decays will release 0.968 MeVCristiano Toàn (talk) 02:04, 17 November 2012 (UTC)

Still unreferenced[edit]

The discussed claim that almost two-thirds of all isotopes currently considered to be stable are theoretically unstable (which is repeated all over the article) is still unreferenced after a full two years! If no proper reference for this very strong claim can be given, practically the whole section Stable_nuclide#Still-unobserved_decay, as well as lots of other article text, would need to be removed because it's based on this unreferenced claim. If it's really "definitely not OR" it does desperately need a citation soon. --Roentgenium111 (talk) 16:45, 13 June 2014 (UTC)

The "isotopes of element X" pages were edited by XinaNicole in 2011 to include this information on predicted decay modes, referencing it to Nucleonica's Universal Nuclide Chart (registration required). I added this link as a reference for this section. (BTW, this predicted info is also in the element infoboxes.) Double sharp (talk) 04:07, 14 June 2014 (UTC)
Thanks; so you can confirm the claims from that chart?
But if this is the only source and there are no secondary sources discussing the theoretical instability of most of the stable isotopes, I think we should still reduce the (IMO) undue weight of discussing these "theoretically instable" isotopes in the article. --Roentgenium111 (talk) 20:02, 2 July 2014 (UTC)
It didn't always require registration, and when XinaNicole added it it didn't: so I assume it must have had this info. But I'm not sure now. Double sharp (talk) 12:59, 4 July 2014 (UTC)
I see; I thought you might have registered there yourself (I haven't either). But the claims in this article were already added in 2009 by V1adis1av, and he only gave a reference for the fact that "many stable [...] nuclides have positive energy release [1] in different kinds of radioactive decays", not for the decays themselves. It's quite possible that XinaNicole's Nucleonica source is also only for the positive mass difference. IMO, it's clearly OR to assume that any process with positive energy is predicted to occur; there are many other conservation laws in nuclear physics... --Roentgenium111 (talk) 14:39, 4 July 2014 (UTC)
It may well give actual predictions for some of the relevant nuclides, though, because XinaNicole also added predicted half-lives for some of these nuclides, such as 196Hg. Double sharp (talk) 14:47, 4 July 2014 (UTC)
Unfortunately, I can't remember where I got those predicted half-lives. I think it was from that site, but I can't be sure, since it's been three years since I worked on those articles. It definitely wasn't OR on my part, but I can't say for sure that it wasn't someone else's OR. Sorry I can't be of more help XinaNicole (talk) 06:42, 5 July 2014 (UTC)


Wouldn't most physicist say that if there's lower energy (double electron capture, double beta) then it's very likely it's not stable it's merely very long half life —Preceding unsigned comment added by (talk) 21:08, 28 February 2010 (UTC)

Yes, but predicting it is one thing, seeing it is another. Hydrogen, and indeed all elements, are predicted to be unstable by proton decay, which is actually allowed (though rare) in standard theory. It hasn't yet been seen. If we put in all the things that could happen in theory, there would be no stable isotopes AT ALL. SBHarris 23:46, 28 February 2010 (UTC)
Let's remember also that there have been theories which have been accepted as standard by "most physicists" but later turned out to be wrong. A responsible encyclopedia must distinguish between observed facts and unproved theories, even if they are consensus theories. Dirac66 (talk) 00:19, 1 March 2010 (UTC)
What you say above, Dirac 66, is a very rare event! For common people like you and me, THEY ARE NOT EVEN WORTH BEING CONCERNED ABOUT. Why do you worry about something that happens in one case out of a million? I suggest that you pay attention to the 999,999 and that would do you a lot more good. (talk) 17:17, 11 August 2012 (UTC)

Confusing sentence in Definition of stability ...[edit]

To Sbharris: I am trying to understand the meaning of an already confusing sentence to which you added the words "greater than" which confuse me even more. The sentence now reads "The shortest half-lives of easily detectable primordially present radioisotopes are around 700 million years (e.g., 235U), with a lower present limit on detection of primordial isotopes of half live greater than 80 million years (e.g., 244Pu)."

Is the following suggested rewrite equivalent? "Primordially present radioisotopes are easily detected with half-lives as short as 700 million years (e.g., 235U), although some primordial isotopes have been detected with half lives as short as (greater than?) 80 million years (e.g., 244Pu)."

Also, the 244Pu article says (in the first sentence) that the half-life is 80 million years, so what does "greater than" mean here? Dirac66 (talk) 14:05, 9 August 2010 (UTC)

I should re-write this so it's impossible to misunderstand. We can detect the primordial presense of isotopes that have half lives greater than 80 million years. For those that half half lives shorter than that, there's too little around to see with present methods. This could change. For the cutoff between Pu-244 and the nuclide with the next-shorter half-life, see list of nuclides. Meanwhile, I'll try to clarify this. SBHarris 18:52, 9 August 2010 (UTC)


I think we should take a tellurium-128 in "stable" isotopes category because with the half life 2.2x10^24 years so that mean only one decay in about 1925 days if we have a mole of this isotopeCristiano Toàn (talk) 10:12, 22 February 2011 (UTC)

Our policy has been to declare any isotope that has a measured halflife (by any means) to be fair game for being a radioisotope (otherwise you get into all the problems mentioned in this article and wind up with only 90 stable isotopes left, all in the first 40 elements).

Te-128 has the longest half life known, but not from direct measurement but geochronology. I believe from measurement by mass spectrometry of excess (stable) Xe-128 (to which Te-128 it has decayed by double beta decay) in rocks containing Te-128. It's a sort of Te/Xe dating, but using the date of the rock found by other means to inversely measure the half life of the Te-128 in it. 2e24 years is what came out. Think of a mole sitting in a rock for a billion years-- If you get one decay every 5.3 years then you end up with 200 million atoms of extra Xe-128. Perhaps enough to count a few. SBHarris 03:39, 16 April 2011 (UTC)

Maximum stability atomic number fallback rationale[edit]

Also note that if the list is ordered by atomic number, we have OE81Tl205 in 4th place behind EE82Pb206, EE82Pb207, and EE82Pb208. And we used to have OE83Bi209 as first, until it was reported that a few of them would occasionally emit an alpha (2He4) particle and drop back into the OE81Tl205 category. And it is the theory that all Bi209 isotopes are identical that causes this event to make us believe that there are no stable 83Bi209 atoms.WFPM (talk) 23:31, 15 April 2011 (UTC) And the estimated halflife of Bi209 is 1.9x!0^19 years. Or maybe an OE83Bi209 atom is just an OETl205 atom with a loose alpha particle??. Incidentally, after the OE83Bi209 atom emits an alpha particle, what does it do with the 2 extra electrons? They must be emitted, with some amount of unaccounted for kinetic energy. Does anybody know these details?WFPM (talk) 17:49, 16 April 2011 (UTC)

If spontaneous fission, why not spontaneous fusion?[edit]

We are saying that any nuclide which is heavier than its potential fission products is theoretically unstable to spontaneous fission, no matter how low the probability. Obviously a nuclide lighter than the iron peak can't transform into matter with higher binding energy in isolation. But most matter, at least for elements beyond the lightest, is not isolated but part of condensed matter. If two nuclides are in proximity, and their fusion would potentially release energy, isn't there some tunneling probability, no matter how small, that the two would eventually fuse, releasing energy?
If it's true that in condensed matter, nuclides both below and above the iron peak will fuse or fission towards iron, why list the former unambiguously as "stable"? --JWB (talk) 17:44, 21 February 2012 (UTC)

Do you have a reference for your claims, or is this original research? Also, stability is normally defined for an isolated nucleus - every isotope will fuse and/or decay when it collides with another nucleus. --Roentgenium111 (talk) 17:51, 30 June 2012 (UTC)
"Spontaneous fusion"? What an odd idea. It never happens. For example, two helium nuclei or two carbon nuclei ever fuse with one another (yielding beryllium in the first case), no matter how extreme the conditions are. Also, as Roentgenium111 pointed out, stability of nuclei is something that is considered one atom at a time. Is one atom of U-235 stable? No. Is one atom of oxygen-16 stable. Yes.<be> (talk) 17:26, 11 August 2012 (UTC)
Under extreme conditions, "spontaneous" fusion does occur, e.g. for hydrogen inside the Sun. But since hydrogen has a "half-life" of billions of years even there, the rate of spontaneous fusion under standard conditions is likely unmeasurably small (but not quite zero, when several atoms are present).--Roentgenium111 (talk) 14:45, 4 July 2014 (UTC)

Stable isotopes[edit]

H-1, H-2 He-3, He-4 Li-6, Li-7 Be-9 B-10, B-11 C-12, C-13 N-14, N-15 O-16, O-17, O-18 F-19 Ne-20, Ne-21, Ne-22 Na-23 Mg-24, Mg-25, Mg-26 Al-27 Si-28, Si-29, Si-30 P-31 S-32, S-33, S-34, S-36 Cl-35, Cl-37 (Ar-36), Ar-38, Ar-40 K-39, K-41 (Ca-40), Ca-42, Ca-43, Ca-44, (Ca-46) Sc-45 Ti-46, Ti-47, Ti-48, Ti-49, Ti-50 V-51 (Cr-50), Cr-52, Cr-53, Cr-54 Mn-55 (Fe-54), Fe-56, Fe-57, Fe-58 Co-59 (Ni-58), Ni-60, Ni-61, Ni-62, Ni-64 Cu-63, Cu-65 (Zn-64), Zn-66, Zn-67, Zn-68, (Zn-70) Ga-69, Ga-71 Ge-70, Ge-72, Ge-73, Ge-74 As-75 (Se-74), Se-76, Se-77, Se-78, (Se-80) Br-79, Br-81 (Kr-78), Kr-80, Kr-82, Kr-83, Kr-84, (Kr-86) Rb-85 (Sr-84), Sr-86, Sr-87, Sr-88 Y-89 Zr-90, Zr-91, Zr-92, (Zr-94) Nb-93 (Mo-92), Mo-94, Mo-95, Mo-96, Mo-97, (Mo-98) Tc-->No stable isotopes! (Ru-96), Ru-98, Ru-99, Ru-100, Ru-101, Ru-102, (Ru-104) Rh-103 (Pd-102), Pd-104, Pd-105, Pd-106, Pd-108, (Pd-110) Ag-107, Ag-109 (Cd-106), (Cd-108), Cd-110, Cd-111, Cd-112, (Cd-114) In-113 (Sn-112), Sn-114, Sn-115, Sn-116, Sn-117, Sn-118, Sn-119, Sn-120, (Sn-122), (Sn-124) Sb-121, Sb-123 (Te-120), Te-122, Te-124, Te-125, Te-126 I-127 (Xe-124), (Xe-126), Xe-128, Xe-129, Xe-130, Xe-131, Xe-132, (Xe-134) Cs-133 (Ba-132), Ba-134, Ba-135, Ba-136, Ba-137, Ba-138 La-139 (Ce-136), (Ce-138), Ce-140, (Ce-142) Pr-141 Nd-142, (Nd-143), (Nd-145), (Nd-146), (Nd-148) Pm-->No stable isotopes! (Sm-144), (Sm-149), (Sm-150), (Sm-152), (Sm-154) (Eu-153) (Gd-154), (Gd-155), Gd-156, Gd-157, Gd-158, (Gd-160) Tb-159 (Dy-156), (Dy-158), Dy-160, (Dy-161), (Dy-162), (Dy-163), Dy-164 (Ho-165) (Er-162), (Er-164), (Er-166), (Er-167), (Er-168), (Er-170) (Tm-169) (Yb-168), (Yb-170), (Yb-171), (Yb-172), (Yb-173), (Yb-174), (Yb-176) (Lu-175) (Hf-176), (Hf-177), (Hf-178), (Hf-179), (Hf-180) (Ta-180m), (Ta-181) (W-182), (W-183), (W-184), (W-186) (Re-185) (Os-184), (Os-187), (Os-188), (Os-189), (Os-190), (Os-192) (Ir-191), (Ir-193) (Pt-192), (Pt-194), (Pt-195), (Pt-196), (Pt-198) (Au-197) (Hg-196), (Hg-198), (Hg-199), (Hg-200), (Hg-201), (Hg-202), (Hg-204) (Tl-203), (Tl-205) (Pb-204), (Pb-206), (Pb-207), (Pb-208) Bi or heavier-->No more stable isotopes! — Preceding unsigned comment added by (talk) 15:50, 12 July 2012 (UTC)

There is also a list in this article. Did you take time to read it? Do you disagree with it? SBHarris 22:50, 12 July 2012 (UTC)
He or she appears to disagree with the inclusion in Te-123 in the list in the article. Double sharp (talk) 11:14, 1 November 2012 (UTC)
Well, they are out of date (see below). Te-123 has a half life at least 5x10^19 years and probably much longer. It is presently observationally stable. SBHarris 02:55, 16 September 2013 (UTC)
I know, and was just clarifying the situation! :-) Double sharp (talk) 10:56, 16 September 2013 (UTC)


Why Te-123 is stable? It's half-life is 5.99E14 year right? — Preceding unsigned comment added by (talk) 15:20, 14 July 2012 (UTC)

No. See isotopes of tellurium. Decay of Te-123 by EC was claimed to have been observed, but more recent observations have not found it, and the report was apparently in error. [2] Te-123 is still observationally stable. In theory it has a half life that has been calculated (as do many other "stable" nuclides"), but (see list of nuclides) our policy here has been to include only nuclides that have more direct evidence of decay, in terms of observation, or historical measurment of decay products in old rocks. SBHarris 02:54, 16 September 2013 (UTC)
I'm quite curious why 123Te is so stable. It must decay, as its electron capture to 123Sb releases energy. What I'm wondering is what inhibits it from this decay (and why the energy released is so small). Double sharp (talk) 15:15, 16 September 2013 (UTC)
Apparently one needs to be a nuclear physicist to understand it. [3]. An even-proton odd-neutron nuclide is capturing an electron to be an odd-proton even-neutron nuclide, and isn't happy about it or that eager to do it. The various influences lined up on both sides of this are apparently nearly balanced. There are a lot of things in nature that are energetically favorable that just don't happen. Decay of all the "stable" nuclides heavier than Z=40, for example. Perhaps we just live on the wrong time scale, is all. SBHarris 05:09, 17 September 2013 (UTC)

Tabulate the Information[edit]

The information on how many elements have how many stable isotopes ought to be TABULATED rather than listed in a very long sentence in the text. The tabulated information would be much faster to read and to grasp.
I tried to tabulate thie information this morning, but then someone who must believe that he OWNS this article reverted my changes. I do not appreciate it. If you did not like my tabulated information, you should have worked on making a better table rather than greedily reverting the work that I had done.
You might not believe it, but tabulated information is often a much better way to present it for ease of comprehension. Otherwise, why would bother making and using tables? (talk) 17:03, 11 August 2012 (UTC)

Perhaps our web-reader programs differ? I see no sentence. I see a carriage-return delimited WP:LIST. This works fine for the purpose, but I have no objection to a table. I fail to find the edit where somebody reverted your conversion of a delimited LIST to a table. Could you point it out? SBHarris 18:31, 11 August 2012 (UTC)

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