Talk:Radon

Image?

The radon article still doesn't have an image of radon. However, i may have found a picture of radon. HAt 12:28, 12 September 2024 (UTC)

What in that picture is radon? And what is the rest? We can only take pictures with suitable licenses anyway. --mfb (talk) 13:03, 12 September 2024 (UTC)

TBH I don't even believe that's radon, just look at it! Thats obviously a solid! HAt 13:08, 12 September 2024 (UTC)

I would assume, based on chemistry and the image, that the bubbles are the radon, as decay products being liberated from the solid. But assuming or analyzing someone else's novel image aren't really viable approaches for encyclopedia content. DMacks (talk) 15:06, 12 September 2024 (UTC)

Also for your information the promethium(III) chloride page has an image that has the same source as the 'radon' picture. HAt 13:10, 12 September 2024 (UTC)

A "non-free" image can be used even contrary to its license in extremely limited cases. That PmCl₃ image is documented as meeting Non-free content criteria. DMacks (talk) 15:06, 12 September 2024 (UTC)

This may count as an image of Radon: https://commons.wikimedia.org/wiki/File:Radon_decay_in_a_cloud_chamber.jpg (source: https://www.nuledo.com/en/our-products/) It visibly shows the decay of Radon gas in a cloud chamber ~2026-44967 (talk) 05:36, 4 March 2026 (UTC)

Picture is already in the article later on. It's not at the top because it is not immediately obvious to a viewer what they are looking at... Ideally it should be pretty obvious that the subject of an image is 1. a gas and 2. visible, and radon is hard to get in quantity for either of those things to be seen.. -- Reconrabbit 14:36, 4 March 2026 (UTC)

Spectrum

What's the reason that the spectra of Radon and Radium are nearly identical (just adding a few lines to get from Radium to Radon)? Compare Radon spectrum vs. Radium spectrum. Shouldn't the lines be completely different? Renerpho (talk) 00:33, 14 January 2025 (UTC)

I've asked again on Wikipedia talk:WikiProject Chemistry#Radon and Radium spectral lines, with some additional comments. I suggest we discuss it there. Renerpho (talk) 01:16, 14 January 2025 (UTC)

Both works are original research according to their descriptions. Johnjbarton (talk) 01:31, 14 January 2025 (UTC)

What the Thayer reference says about Radon.

The source

• Thayer, John S. (2010). "Relativistic Effects and the Chemistry of the Heavier Main Group Elements". Relativistic Methods for Chemists. Challenges and Advances in Computational Chemistry and Physics. Vol. 10. p. 80. doi:10.1007/978-1-4020-9975-5_2. ISBN 978-1-4020-9974-8.

was mentioned in a recent edit summary between @DMacks and @The Young Prussian. The source says:

• No compounds in the +8 state have been reported or even claimed. RnF8 is predicted to be unstable towards loss of fluorine [214]. By analogy with Xe, the most likely Rn(VIII)compound to be isolated would probably be Ba2RnO6, the radon analog of barium perxenate.

In my opinion the notable sentence is the first one, not the last one. Johnjbarton (talk) 02:40, 7 April 2025 (UTC)

Thanks for checking. I was only focused on the spelling of the chemical. This area of chemistry isn't my specialty. DMacks (talk) 03:18, 7 April 2025 (UTC)

In any case: per the Red Book (p. 338) the anion name for Rn is radonate. (For Ra it is radate.) Double sharp (talk) 07:25, 28 May 2025 (UTC)

Notes on GA

I was trying for a long while to bring this article to GA status but gave up after a lot of searching around for subpar sources and getting stuck in certain places. @Keresluna, I would pay special attention to the following section headings where I felt there needed to be more citations or more information in general:

• Industrial production
• Inhalation and smoking
• Absorption and ingestion from water

The latter two I wrote "needed review"; I leave it to you. Because of how heavily involved I was in writing the article I don't think I could give an impartial review. -- Reconrabbit 15:34, 6 June 2025 (UTC)

I withdrew the nomination. I do not think I will have time for this during the summer. Sorry for this. Keres🌕Luna ^edits! 17:17, 6 June 2025 (UTC)

Okay, understood. Maybe I will nominate it myself once I am done with the rabbits. -- Reconrabbit 17:27, 6 June 2025 (UTC)

Misleading image?

@Arònel123 and Double sharp: I'm not so sure about using File:Radon86.jpg as the image for radon. As the caption says, the blue-green glow comes from the phosphorescence of zinc sulfide irradiated by radon. Of course, since (neutral) radon is invisible, we're only seeing zinc sulfide here. My biggest concern is that this image could very easily mislead readers to think radon glows green, especially when the image doesn't have a caption in the article. In reality, radon (or more specifically, when ionized in a vacuum environment like a gas-discharge lamp) glows magenta/pink according to its blue-and-red-dominated emission spectrum. There's also this website cited in the Wikipedia article that mentions solid radon glowing yellow to orange to red (speculating here---I think it's due to thermal radiation from its intense radioactivity?).

With that being said, I prefer this image be removed. Any other radioactive element like tritium or radium can cause the zinc sulfide tube to glow green like in this image. Nrco0e (talk • contribs) 22:58, 16 April 2026 (UTC)

I do not think there is ever going to be a good way to represent Rn such that it would be appropriate to depict in the infobox. It is simply infeasible to get a quantity of radon large enough that could be visualized in a useful way (excitation) as far as I know. One day I'd like to bring this article to good-level, at least clearing up all the obvious problems like uncited or confusing sections, but getting a good infobox image is not in my plans. -- Reconrabbit 23:59, 16 April 2026 (UTC)

I also don't think you could ever practicably get it. (No one is going to repeat the melting point measurement of Ramsay and Gray in 1909 due to the radiation hazard, I imagine.) Some things just aren't going to get pictures and I think this is one of them. Double sharp (talk) 07:02, 17 April 2026 (UTC)

Admittedly, the photos for actinium are also severely indirect as quite literally,what you see there is not the element, but rather the glow from the element.(astatine is also like this,howver as astatine is probably wayyy to radioactive to find a better photo of I allow it.)And even the promethium image...the one at wikiproject element photos is according to the source, a thermal gradient,and the infobox photo is a solution of promethium ions. Arònel123 (talk) 13:32, 20 April 2026 (UTC)

Also, I have just added a caption to the image to hopefully avoid confusion. Arònel123 (talk) 13:43, 20 April 2026 (UTC)

I tried to add a caption but had trouble with that. The purpose of the infobox image is to show what the pure element looks like. I do not see it as useful to show a reader at the first look that "this element looks like a glowing liquid" if that is not the case. As I have read At-211 is eluted in nitric acid; a reader is looking at glowing nitric acid and assuming that is astatine. Same with promethium - the image is an aqueous solution with an organic ligand, so clearly not the pure element. Perhaps these images are useful later on with context and captions but not as the first thing a reader sees. -- Reconrabbit 13:52, 20 April 2026 (UTC)

by added a caption for radon, I meant i added a caption like 3 seconds before I replied Arònel123 (talk) 13:54, 20 April 2026 (UTC)

btw I agree with you Arònel123 (talk) 13:55, 20 April 2026 (UTC)

i think they suffice *if* with captions Arònel123 (talk) 13:56, 20 April 2026 (UTC)

for adding captons I just add "|image caption=(insert what u want)" to the infobox Arònel123 (talk) 14:08, 20 April 2026 (UTC)

Weird, I don't see the caption in the infobox, but I do see it in the source code. Hydrogen's infobox does have a caption, but I can't find it in its source code though. I'll need to look more into this... Nrco0e (talk • contribs) 16:39, 20 April 2026 (UTC)

Aha. You can edit the caption over here Template:Infobox element/symbol-to-top-image-caption. I have no clue why the element infobox caption is a global parameter on a totally different page, that's so weird. Nrco0e (talk • contribs) 16:45, 20 April 2026 (UTC)

Yeah thats so weird I wonder why? Arònel123 (talk) 01:25, 21 April 2026 (UTC)

Admittedly, the photos for actinium are also severely indirect as quite literally,what you see there is not the element, but rather the glow from the element.(astatine is also like this,howver as astatine is probably wayyy to radioactive to find a better photo of I allow it.)And even the promethium image...the one at wikiproject element photos is according to the source, a thermal gradient,and the infobox photo is a solution of promethium ions. Arònel123 (talk) 13:38, 20 April 2026 (UTC)

(sorry I accidentally duplicated it Idk how) Arònel123 (talk) 13:45, 20 April 2026 (UTC)

I think you forgot that this comes from a book (https://archive.org/details/matterlapp00lapp/page/n3/mode/2up) where there is real radon in the tube; the blue color is from the radioactive radon, and only radon glows like that. I3rwiiwjiwji (talk) 21:33, 20 April 2026 (UTC)

As the book states, the radon is not glowing. The zinc sulphide is glowing because of the ionizing radiation. It is not sealed in the tube. -- Reconrabbit 00:16, 21 April 2026 (UTC)

Apparently the photo has just been deleted... Arònel123 (talk) 03:25, 21 April 2026 (UTC)

Also when reading the book it seems to say notthat they coated the inside of the tube that was filled with radon with zinc sulfide which made it glow,it seems like they filled a tube with radon and put it on a soft of surface made of zinc sulfide which proceeded to glow...if it is *that* strong...yeah tritium or Radium are nowhere near radioactive enough to do that and zinc sulfide does not grow blue...I suspect that it is from the alpha particles ionizing the atoms... Arònel123 (talk) 03:36, 21 April 2026 (UTC)

https://books.google.com/books?id=T0Iiv0BJ1E0C&pg=PA13#v=onepage&q&f=false This book states that radon changes color when in solid form. I can only assume this is based on the 1909 experiments by Ramsay and Gray but they even state that the color varies due to the composition of the glass it's kept inside. I'm just repeating what Double sharp said but it's extremely unlikely we'll ever see solid or even liquid radon (which is colorless anyway). -- Reconrabbit 13:30, 21 April 2026 (UTC)

uhh being colorless does not make it disqualified being invisible does (ln2 for example is colorless) and I'm pretty sure that plasma ain't colorless) Arònel123 (talk) 07:27, 23 April 2026 (UTC)

That's true about colorless liquids, my mistake. I don't know what you are calling a plasma. -- Reconrabbit 13:29, 23 April 2026 (UTC)

specifically I would not be very surprised if the blue part is plasma though it might also just be straight up the ionization of air and anyway I don't see how a misleading image makes sense here I mean for astatine we literally use glowing nitric acid for the infobox the astatne is not what you see there what you do see there is just straight up the ionization of air. Arònel123 (talk) 07:40, 29 April 2026 (UTC)

Probably nobody has paid too much attention to it yet, that image was added to At just 2 months ago. -- Reconrabbit 12:15, 29 April 2026 (UTC)

Makes sense, considering noone ever expected a image to ever exist, though I am surprised as astatine is frequently checked thanks to it's popularity as "the rarest element"...though i seriously have absolutely no idea how the original radon image is better than the infobox replacement...which is just the spectral lines for radon...and either way the actinium image has been there for ages and is similar. Arònel123 (talk) 12:29, 29 April 2026 (UTC)

I mean,the actinium image has been here since 2020... Arònel123 (talk) 04:02, 30 April 2026 (UTC)

I assume that is a nitric acid solution as well? -- Reconrabbit 14:14, 30 April 2026 (UTC)

Possibly Arònel123 (talk) 03:30, 1 May 2026 (UTC)

Though the image in the infobox for Actinium-225 is actinium nitrate...I know nothing wih certainty abut the image in the actinium infobox itself... Arònel123 (talk) 03:32, 1 May 2026 (UTC)

Radon 222 is not trace

Radon 222 is the most abundant isotope. ~2026-48331-50 (talk) 16:36, 7 September 2026 (UTC)

The {{infobox radon}} relies on the NUBASE 2020 source which in turn cites

• Meija, J., Coplen, T. B., Berglund, M., Brand, W. A., De Bièvre, P., Gröning, M., ... & Prohaska, T. (2016). Isotopic compositions of the elements 2013 (IUPAC Technical Report). Pure and Applied Chemistry, 88(3), 293-306.

for "Isotopic abundances" but the Meija source only lists stable isotopes and thus does not include Radon at all.

I found a source to correct the table. Johnjbarton (talk) 19:44, 7 September 2026 (UTC)

"Trace" ought to be correct for the secondary radioelements that only really exist as daughters of Th and U in general. (The problem with giving actual numbers is that they will depend on the source: Rn from a mineral with thorium but little uranium will be mostly the 220 isotope, not the 222 isotope.) Double sharp (talk) 09:26, 8 September 2026 (UTC)

@Double sharp trace would be appropriate if the column was abundance in Earth crust, but afaict this is isotopic abundance. Johnjbarton (talk) 20:15, 8 September 2026 (UTC)

@Johnjbarton: This is how all the other trace radioelements are treated (except Pa), just see their infoboxes. The CIAAW does not give numerical isotopic abundances for them either (except Pa), and I already explained why there is a problem: you cannot know the natural isotopic abundances of such elements without a knowledge of the history of the sample. (So it is worse than things like radiogenic ⁸⁷Sr from Rb decay, or the variations in Pb isotopic abundances from Th and U decay. Again, Pa is an exception because ²³¹Pa dominates so utterly.) Double sharp (talk) 04:54, 9 September 2026 (UTC)

So we have one source that says nothing and one that gives values. I would grant CIAAW (Meija) is the authority so we could go with "nothing". But I don't see any source for "trace". Having all naturally occurring isotopes listed as "trace" is not correct, they logically need to add to 1.0 (100%). The value "trace" makes it appear that a mistake was made conflating natural isotopic abundance with Abundance of elements in Earth's crust Johnjbarton (talk) 15:27, 9 September 2026 (UTC)

It's not a conflation. It would be wrong to give abundance values for trace radioelements because they vary too much from sample to sample to be useful. It would equally well be wrong to give no value and say they do not exist in nature at all. That is the entire point behind the "trace" and "syn" in all element and isotope infoboxes: these are all isotopes where there is no sensible standard natural abundance to speak of (CIAAW is a reasonable source for that), but one can readily answer the question "but does it exist in nature or not" with reference to the well-known actinide decay chains for those heavy elements, and just as it would be misleading to give a figure for how much natural Rn is Rn-222, it would be wrong to say there isn't any. Double sharp (talk) 11:39, 12 September 2026 (UTC)

Giving no data is not at all the same as giving incorrect data. Giving "trace" for natural isotopic abundance is simply incorrect. We should follow CIAAW and give no value. Johnjbarton (talk) 15:29, 12 September 2026 (UTC)

As I already said: I disagree that it is incorrect. Traces of Rn-222 exist in nature, but it doesn't make sense to give a number for its abundance, and "trace" with a link to Trace radioisotope seems to be a reasonable one-word summary fit for an infobox for this situation. It is also exactly how every other element infobox where this is relevant treats this situation, along with the isotopes list like Isotopes of radon. If you think there is a better word for it, feel free to suggest it, but on the grounds of consistency and the fact that "trace radioisotope" is a term that exists, I see no issue with "trace". It's no more wrong than calling carbon-14 or tritium trace radioisotopes in their infoboxes (in cases where C and H are obviously very abundant in the crust in their stable forms). Double sharp (talk) 12:12, 13 September 2026 (UTC)

@Double sharp Please read what I am writing. I think you have something in your mind that is not actually present in the article content.

I completely agree with your statement Traces of Rn-222 exist in nature, but it doesn't make sense to give a number for its abundance, and "trace" with a link to Trace radioisotope seems to be a reasonable one-word summary fit for an infobox for this situation. I would agree to use "trace" for abundance of Rn in nature. But that is not what we are talking about here.

I understand that you made this change to Template:Infobox radon isotopes believing that "trace" indicates a "number for its abundance". However that column of the table is not Abundance of the chemical elements. That column of the table links isotopic abundance which is The relative number of atoms of a particular isotopes in a mixture of the isotopes of an element, expressed as a fraction of all the atoms of the element, per IUPAC. In the case of radon, "all the atoms of the element" are too few for CIAAW to report the fraction for each isotope.

The value "trace" is also incorrect according to both sources we have. One source gives no value and one gives a value. No source says "trace" or anything similar.

The Isotopes_of_carbon is also incorrect. The authoritative source, https://ciaaw.org/carbon.htm, gives no value. It does not say "trace" or anything similar.

The Tritium page is correct. It reports the natural abundance as 10⁻¹⁸ in hydrogen with a source. Neither the wikipedia article nor the source cited says "trace".

Not a single element in https://www.degruyterbrill.com/document/doi/10.1515/pac-2015-0503/html is listed as "trace".

I hope you will reconsider. Johnjbarton (talk) 16:36, 13 September 2026 (UTC)

Isotopes of hydrogen gives T as a trace radioisotope. "Trace radioisotope" (not just "trace" for an entire element) is at least a term we have a Wikipedia article for, and the precedent of all other natural element articles. I am arguing that "trace" is a pretty correct way to describe the abundances of not just Rn in the crust, but ²²²Rn or ¹⁴C or T. For example, here's a source calling ⁴¹Ca a trace radioisotope (and simultaneously giving a range for its abundance, true, but that's for a case where we have stable primordial Ca isotopes to compare to).

In any case, if we are to change the term "trace" for such isotopes, I would argue that we should change it simultaneously for all elements, not just Rn. Double sharp (talk) 16:56, 13 September 2026 (UTC)

For any element with stable isotopes, "trace" might be used for a radioisotope if we have a reliable source giving a value for its isotopic abundance. That source cannot be NUBASE2020 as now. The description of the NUBASE2020 table specifically excludes radioisotopes: The NUBASE2020 evaluated nuclear data library contains the recommended values for the basic nuclear physics properties for all known nuclei, such as mass excess, excitation energy of the excited isomeric state, half-life, spin and parity, decay modes and their intensities, isotopic abundance (for stable nuclides), year of discovery, as well as the corresponding bibliographical information. Obviously the NUBASE2020 cannot be used for elements like Rn with no stable isotopes.

I agree that we should be consistent and change all of the places where isotopic abundance is sourced to NUBASE2020 and the entry is "trace". The entry could be "-" or "NA" or "unreported" or "unstable" (linked to trace radioisotope) or footnoted to "Radioisotopes are not stable and are not assigned isotopic abundance by CIAAW" ref to Meija IUPAC report. Do you have a preference or alternative for the entry? I will make a proposal on WT:Elements for such a site wide change. Johnjbarton (talk) 20:42, 13 September 2026 (UTC)

@Johnjbarton: To me, the current situation is about the best possible, although I suppose we should technically be adding a source for each "trace" to confirm that the isotope does occur in nature. At some point we would have to decide when it gets pedantic, i.e. should we include as trace extremely rare branches in the natural decay chains like ²⁰⁶Hg (which could easily be proved by citation to be a ²³⁸U daughter, it's just that the branch is so rare that it's not usefully one), the neptunium series (which exists because ²³⁷Np does), and things like ⁹⁰Sr (which is indeed natural as a spontaneous fission product of ²³⁸U, but would be completely swamped by anthropogenic ⁹⁰Sr; on the other hand, by that logic, we'd have to call Tc and Pm synthetic because the natural amounts produced by spontaneous fission of uranium are surely swamped by the artificially produced amounts, and I'd guess off the top of my head that this would also hold for Np and Pu but probably not At and Fr). So I suppose to avoid this kind of pedantry, the best alternative to "trace" might be a bespoke explanation of where those natural traces come from, like "cosmogenic", "²³⁸U daughter", "spontaneous fission product", etc. Of course this then would get so complicated and large for the infobox that if you asked me about a preference or alternative I would say "leave well enough alone, keep it as 'trace', and perhaps just add a source saying why it exists in nature even though hopefully the main article explains it already".

Incidentally, it would be quite wrong to say that radioisotopes are not assigned isotopic abundance by CIAAW. That misses the point of why most of them are not included. Primordial radioisotopes like ²³⁸U, or at least long-lived ones where there isn't doubt about the parentage like ²³⁰Th, ²³¹Pa, and ²³⁴U, are for sure included by them. Double sharp (talk) 03:46, 14 September 2026 (UTC)

No, not "technically", WP:Verifiability is a policy. It is not pedantry, it is what we do every day. But you are still completely missing my point.

Calling the isotopic abundance of ⁴¹Ca "trace" based on NUBASE2020 is just a {{failed verification}} case. Annoying but not that big of a deal. We could probably find a source which tells us it occurs. This is likely to be true for all of the "trace" values in our elements which have stable isotopes. I vote to ignore all of these cases.

Calling the isotopic abundance of ²²²Rn "trace" is factually incorrect. The isotopic abundances add to 100% by definition.

You are the one who wants "consistency", but setting unknown isotopic abundance to "trace" is not consistent: it is incorrect for some elements but lazy for others. I'm fine with lazy, but I am not fine with incorrect. Johnjbarton (talk) 04:34, 14 September 2026 (UTC)

@Johnjbarton: I'm precisely not fine with incorrect. That is why I do not accept your argument. Sure, the abundance of Rn isotopes is not well-defined by a number, and there was no requirement that a set of non-numbers should add to 100%. Or would you claim that the isotopic abundances of Cm should add to 100% when obviously every entry should be "synthetic"? Double sharp (talk) 16:08, 14 September 2026 (UTC)

The isotopic abundance of ²²²Rn is not a trace amount. It is somewhere between 0.9 and 1.0 depending on how soon the measurement is made after separation from the other material. Reporting it as "trace" is incorrect as well as being unverified in the source given.

The isotopic abundances of Cm should all be WP:verifiable. They should all be "(unstable)" if sourced to CIAAW. In my opinion Curium should not have a column of natural isotopic abundance because it will never have any values. Johnjbarton (talk) 16:27, 14 September 2026 (UTC)

It won't be that if your original material was extremely rich in Th and depleted in U. Then it is perfectly possible for ²²⁰Rn to be more common than 9% if you measure the air right next to your Th-rich rock.

Anyway, let me spell it out. "Trace" simply means "this is a natural radioisotope but there is no sensible numerical value for an isotopic abundance". That is all it means and it does not mean that the percentage of Rn atoms in the wild that are ²²²Rn is some minuscule fraction of a percent. The very fact that ²²²Rn can easily dominate in one natural sample, while ²²⁰Rn could outright dominate in another (measure right next to a chunk of thorianite), is the entire point behind why there is no sensible numeric value here. "Synthetic" means "this is not a natural radioisotope at all". And, obviously, for a natural radioisotope with a perfectly sensible isotopic abundance like ²³⁸U, we give a value (99.3%, FWIW). If you want to say "the isotopic abundances add to 100% by definition", then by that logic they should also do that for synthetic elements, and obviously they don't. These are categorical entries and not numerical abundances!

Certainly, we should I suppose add another source listing the natural decay chains to establish that the relevant daughters of ²³⁸U, ²³⁵U, and ²³²Th are all natural trace radioisotopes. ("Relevant" because of the cases of ²³⁰Th, ²³¹Pa, and ²³⁴U, where for other reasons there is a sensible numeric value.) That does not mean there is anything wrong with the word "trace" being used as a shorthand, though I'd be happy to propose explicitly stating the definitions I'm giving you in the documentation, or finding an alternative to "trace" that is perhaps a little less open to misinterpretation.

Of course you could also object that there isn't really a good definition for what is natural and what isn't. On the one hand, it seems bizarre not to call ²²³Fr natural when it was discovered as a ²³⁵U daughter from natural sources. On the other hand, it's less common in nature than literal ⁹⁰Sr as a spontaneous fission product, and then we seem to be running straight into the problem that it's not useful to call ⁹⁰Sr natural when its anthropogenic supply outweighs its natural supply (whereas for ²²³Fr, the issue is that it's so short-lived that we can't really beat nature on sheer quantity). So I suppose we should discuss what exactly the line for "trace" vs "synthetic" actually is, and while it would to me be somewhat allowing pedantry to outweigh usefulness, I could reluctantly accept removing the distinction completely. Still, this is a different question from whether the current system makes sense or not, to me. Double sharp (talk) 05:46, 15 September 2026 (UTC)

Yes I understand that to you "Trace" simply means "this is a natural radioisotope but there is no sensible numerical value for an isotopic abundance". But in a column of isotopic abundance 'trace' would more likely be read as its dictionary definition: A trace amount is a very small quantity of a substance that is barely detected. We shouldn't ask readers to read your mind or do puzzles to understand the page.

I don't have any problem with "synth" because it cannot be confused with a numerical value for isotopic abundance. I would prefer "(synth)" to emphasize that this not a value.

I think we should do four things:

1. Swap Natural abundance with Isotopic abundance. Natural abundance is an ambiguous shorthand for natural isotopic abundance, which is a subtopic of isotopic abundance.
2. Beef up the content on isotopic abundance. Among the additions would be content on stable isotopes, unstable isotopes, uranium, atomic weight etc. (This content is probably in other articles).
3. Change the column heading in the elements tables to "Isotopic abundance", it is very unclear as "abundance".
4. Change "trace" to "(unstable)" and link to the section of Isotopic abundance that will say only stable isotopes have such values.

This accomplishes everything that "trace" does today without the confusion about the value of a fraction being barely detectable.

Would you support #3 and #4? Johnjbarton (talk) 17:42, 15 September 2026 (UTC)

@Johnjbarton: Almost. My problem with "(unstable)" is that you can perfectly well have isotopes that are unstable but have a reasonable numerical value for abundance, like ²³⁸U or ⁴⁰K. I'd be happy with a different word, but can't quite think of one right now (maybe it's my failure of imagination). If nothing else comes to mind, we could replace "trace" with a symbol like † and refer it to a footnote saying "This is a natural non-primordial radioisotope: no value for isotopic abundance can be given". Double sharp (talk) 18:06, 15 September 2026 (UTC)

Any sourced isotopic abundance would appear as it does now. The entry "(unstable)" is specifically for cases where the source is silent on a value. So ²³⁸U and ⁴⁰K would not change. Johnjbarton (talk) 02:33, 16 September 2026 (UTC)

@Johnjbarton: Sure, but I'm objecting to the implication that only stable isotopes have such values, when the problem is not so much instability, but instability with too short a half-life. (Looking at the list of nuclides it seems the shortest-lived natural nuclides that CIAAW gives abundances for are ²³⁰Th and ²³¹Pa which have half-lives between 10⁴ and 10⁵ years. Though there are cases longer-lived than these two, like cosmogenic ⁴¹Ca, which it does not do the same for.) Double sharp (talk) 08:39, 16 September 2026 (UTC)

Anyway, summoning ComplexRational (with whom I've previously discussed the ⁹⁰Sr problem) for his opinion. Double sharp (talk) 06:48, 15 September 2026 (UTC)

I think you need @ComplexRational with the @ to complete the spell. Johnjbarton (talk) 17:43, 15 September 2026 (UTC)

@Double sharp and Johnjbarton: I've always interpreted trace to mean "present in nature, but only transiently, and not in a reliably measurable quantity". The classification of decay products of primordial radionuclides as trace isotopes is unambigious, though it is harder to establish a consistent classification for cosmogenic nuclides, cluster decay products, fission products, and anthropogenic isotopes that have not had enough time to decay to negligible quantities.

As for the points above:

1. I like the term natural isotopic abundance better, but most academic sources shorten it to natural abundance.
2. Agreed, though I haven't had a chance to evaluate the articles in question.
3. Agreed, and this should match whatever article title is chosen per point (1).
4. I prefer footnotes to (unstable) largely per Double sharp's reasoning. Alternatively, we could make the distinction for different sources of short-lived radioisotopes.

In any case, we still have to decide where to draw the line – for instance, ²¹⁷Rn occurs only in a rare branch of the already-rare neptunium series, so would it be appropriate to give it the same treatment as ²¹⁹Rn, ²²⁰Rn and ²²²Rn? ^Complex/_Rational 18:59, 23 September 2026 (UTC)

For the purpose of isotopic abundance, the line is "does the source list an abundance"? Yes then give it, No then (unstable) for natural occurring and synth for synthetic. No radon isotope has a sourced abundance so only remaining question is naturally occurring. All four of these occur naturally, all four would be (unstable).

Regarding "present in nature, but only transiently, and not in a reliably measurable quantity", that's a fine definition of "trace" which is why I objected to its uses as a fractional isotopic abundance. Johnjbarton (talk) 00:36, 24 September 2026 (UTC)

Photo of radon needs context ( and some additional research? )

The current photo depicts a gold brachytherapy "seed" - a gold tube filled with radon gas. The beta ( and to a lesser extent gamma ) radiation escaping the tube excites the phosphor. These seeds were usually in the range of 0.1 - 10 millicurie range. The image likely needs context - as it "appears" to almost be a glass / transparent vial when in natural light would appear to be a section of gold wire, it also appears to be producing the light illuminating the powder. I suspect the image itself in a journal / article was cribbed from elsewhere so it may be possible to hunt that down with some sleuthing.

This is an image I shot of about 2 microcuries / 13 picograms of radon in air ( 2 parts per quadrillion by mass of air ) which is exciting a ZnS(Ag) powder coated screen inside the tube causing it to emit blue light. Similarly, a side by side comparison of the tube: long exposure in complete darkness vs short exposure in low light. This sort of depiction is perhaps closer to the idea that (a) radon is an invisible gas (b) trace quantities are highly active (c) the otherwise invisible radiation from radon and its decay products can be detected using radioluminescent materials - this is the basis for the Lucas cell. -- Bob (talk) 20:59, 17 September 2026 (UTC)

I've tried to remove the image that's currently on the article but have been reverted several times so I just gave up. These images are significantly nicer, though, and don't make it seem like radon is this vibrant glowing gas - rather an invisible gas whose effects can be observed. Are you willing to upload these images to Wikimedia Commons? -- Reconrabbit (talk) 14:14, 18 September 2026 (UTC)