Talk:Isotope

From Wikipedia, the free encyclopedia
Jump to: navigation, search
          This article is of interest to the following WikiProjects:
WikiProject Elements / Isotopes  (Rated C-class, High-importance)
WikiProject icon This article is supported by WikiProject Elements, which gives a central approach to the chemical elements and their isotopes on Wikipedia. Please participate by editing this article, or visit the project page for more details.
C-Class article C  This article has been rated as C-Class on the quality scale.
 High  This article has been rated as High-importance on the importance scale.
Taskforce icon
This article is also supported by the Isotope Taskforce.
 
WikiProject Chemistry (Rated C-class, High-importance)
WikiProject icon This article is within the scope of WikiProject Chemistry, a collaborative effort to improve the coverage of chemistry on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
C-Class article C  This article has been rated as C-Class on the project's quality scale.
 High  This article has been rated as High-importance on the project's importance scale.
 
WikiProject Physics (Rated C-class, High-importance)
WikiProject icon This article is within the scope of WikiProject Physics, a collaborative effort to improve the coverage of Physics on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
C-Class article C  This article has been rated as C-Class on the project's quality scale.
 High  This article has been rated as High-importance on the project's importance scale.
 

Italics[edit]

Why is most of the Isotope vs. nuclide section italicized? --Akhil 0950 (talk) 04:18, 21 January 2012 (UTC)

I've changed it for now. --Akhil 0950 (talk) 04:21, 21 January 2012 (UTC)

Organization of information[edit]

Given that the meaning of the word Isotope is about the variation of neutron constituency (extra neutron content) within a given (Z Proton number) element, The subject matter of isotope constituencies is not just of an individual element, but about the interelationship of the isotopes of one element with those of the adjacent elements and with relation to the nucleon accumulation process. Thus the subject matter of isotopes is closely related to the element periodic table as a means of determining the interelationship of the various elements with each other. Thus a properly formatted Table of nuclides is necessary in order to maintain a sufficient system of organization of the elements in order to create a forum for discussion. However, since the process of accumulation of the nucleons into the atomic structure does not significantly involve the existence of the electrons, other than as a means of dissipating excess kinetic energy, the chemistry of the individual isotope is not a significant factor related to the process. And thus there remains the necessity for a forum for the discussion of the isotopic information, like why the isotope EE62Sm144 should be stable whereas the isotope EE62Sm146 is an unstable alpha particle emitter.WFPM (talk) 16:16, 18 April 2012 (UTC)

Only one million times the age of the universe?[edit]

From the section Radioactive, primordial, and stable isotopes: Many other stable nuclides are in theory energetically susceptible to other known forms of decay, ... but no decay has yet been observed. The half-lives for these processes often exceed a million times the estimated age of the universe, ...

This seems a serious underestimate since the age of the universe is about 4 x 1017 s, while the measured half-life of Te-128 (as per Primordial nuclide is 6.9 x 1031 s, presumably determined by measuring the tiny bit of radioactivity it does emit. So if there are apparently stable nuclides whose estimated half-life is only 1024 s or so, their radioactivity should have been detected also by now. Should we modify the statement above to "The estimated half-lives for these processes generally exceed 1014 times the age of the universe, ...", or have I misunderstood something. Dirac66 (talk) 01:04, 9 July 2012 (UTC)

Te-128, like Ba-130, is famous for being one of those isotopes that has a half life detected indirectly by decay products over billions of years, not by directly detecting decay (so it's NOT by measuring radioactivity it does emit). Nearly all the nuclides with ages over 10 billion times the age of the universe (4e26 sec), the decay half life of Bi-209, are double-beta decay radioisotopes [1], and these are notoriously hard to measure. For example, the half life of Xe-136 is in dispute, with liquid xenon detectors putting it over 4 x 10^32 sec = > 10^15 or a quadrillion times the the life of the universe. Probably everything over Bi-209 (the longest I know of, offhand, done directly) needs checking for source. If you look at the isotopes in list of nuclides that are presumed unstable but with nothing seen yet, you can see that some are presumably radioactive but have half lives even smaller than Bi-209. All those longer than Bi-209 but one, are these double-beta decays (there's also one single beta-decay). I don't know what the longest-lived double+beta directly-detected nuclide to age of universe is. So some of the difficulties in measurement depend on the element. Obviously, something that forms a nice clear transparent liquid, like xenon (or the protons in water checking for proton-decay), are easier to look at directly, than solid opaque elements. SBHarris 20:05, 9 July 2012 (UTC)
OK thank you, I think I understand. So Te-128 decay could be observed by measuring the accumulated Xe-128 trapped in some rock of known age. And this very long half-life could be measured because inert gas formation in a rock is a very favorable case, as for K-Ar dating (where the half-life is known and the age is not).
The one million in the text is OK then, but I would change a few words for clarity. What say you to the changes in boldface? "Many other stable nuclides are in theory energetically susceptible to other known forms of decay, such as alpha decay or double beta decay, but no decay products have has yet been observed. The predicted half-lives for these nuclides processes often exceed a million times the estimated age of the universe,..."
Also in the article on Radioactive decay, perhaps you could eventually add a paragraph briefly indicating the (overlapping) half-life ranges for the different experimental methods. After your reply above I can now think of 3 - decay products for very long t, direct measurement of radioactivity for intermediate time scales, and resonance widths for very short-lived nuclides. And I will not be surprised if there are other methods needed to cover the 55 orders of magnitude. Dirac66 (talk) 00:36, 10 July 2012 (UTC)
Yes. The one million is something I picked at random. It can be at least a billion, due to Bi-209. If you want to see the ratio of half-life to universe age, look at that figure in the last table in primordial nuclide. A few of the upper ones are indirect half lives, but Bi-209 was genuinely measured at 1.4 billion times the age of the universe or so (I have only 1 sig figure in the table), so this is possible directly. Some of the beta-betas that are longer might be even longer-- I haven't looked them up. SBHarris 00:52, 10 July 2012 (UTC)
Since the exact value of the ratio is not very meaningful, let's just replace one million times by much longer than. Dirac66 (talk) 01:15, 10 July 2012 (UTC)
If you would plot the Element stability profile of these elements, 52Te Tellurium and 54Xe Xenon, then the logic of the instability occurrences and the rationale of the stable isotope data become much more apparent with relationship to each other and show that you are talking about high extra neutron outliers that have a tendency for beta minus decay modes. The stability trend line for this area is noted to run through the intermediary monisotopic element element OE53I127 with 21 extra neutrons and a trend line formula of A = 3Z - 32. So the 28 extra neutrons of EE54Xe136 show the atom to have an exceptionally balanced (completed?) structure, which then decays at the beginning of the beginning of the creation of the next 2 elements (Alpha particle?).WFPM (talk) 04:36, 2 December 2012 (UTC)

History before Soddy[edit]

It is interesting to learn from today's footnotes added by Cwkmail that Soddy's idea of isotopes (presumably without the word) was anticipated by others in 1909-10, and also that Preyer used the word "isotope" with a different meaning as early as 1893. However I question the explanation ["In other words ..."] of Preyer's definition. It seems to me that Preyer's words refer to elements as "isotopic" if they are in the same row (e.g. Si, P, S and Cl), whereas the explanation refers to similar properties and the same column. I suggest deleting this explanation and just leaving Preyer's words (in German and in English). Dirac66 (talk) 20:00, 6 September 2012 (UTC)

Statistics need an "as of" date[edit]

This article and a few other articles contain many statistics such as number of stable isotopes with even and odd mass, number of primordial ..., etc. etc. However these numbers seem to change often, presumably as new results are reported. So it might be a good idea to date the statistics with footnotes saying "As of November 2012" etc. Dirac66 (talk) 23:07, 4 November 2012 (UTC)

Significant data[edit]

It is also true that a lot of the instability data concerning the modes of decay of the various isotopes is of a nature so as to not indicate the true nature of the stability characteristic of the element over the determined possible range of atomic numbers. this is because of the occurrence of isomers of some of the isotopic numbers which have been determined to have shorter halflives than their less unstable associates. So in order to understand the true stability characteristic of a given element it is best to organize the data into a chart that shows a graphic profile of the halflives of the various isotopes of an element so that the maximum halflife (or preferibly the base 10 logarithm of the halflife) can be compared for each of the atomic numbers of the concerned element. A chart of this nature is the best cognizant method of showing the atomic stability tendency of an element and is capable of acting as a discriminant in indicating any significant inconsistencies in the reporting of the data re the more significant properties.WFPM (talk) 05:50, 2 December 2012 (UTC)

Relevance of odd-even existence data to this article[edit]

The section on existence of various naturally occuring primordial nuclides according to the parity of their N, P and total nucleon number has just been copied to (but not moved to) the atomic nucleus article, where it is claimed by one editor that it is more relevant. From my point of view, since this data discuses characteristics of naturally occuring atomic nuclei, and it is the nuclei which make the difference between nuclides, it seems obvious to me that this data is just as relevant in one place as the other. Thus, I have no problem with it being copied, but would hate to see it disappear here.

The question of whether all this data is more appropriate for the article on isotope vs. nuclide naturally arises, and I myself think it goes better in nuclide. But this was argued out and the consensus was that most people look for this data under isotope and therefore the nuclide article should contain little more than the 1947 origin and distinction of this term, plus the (minor) ways that the two terms differ. So that's what we've done. We once had an article called Isotope and nuclide and editors liked that even less. Comments? SBHarris 22:53, 8 March 2013 (UTC)

I think that forking such a large chunk of detailed technical information to two different places is not good, and thank User:Sbharris for pointing it out. The separate copies will inevitably diverge over time, and an editor may work diligently on one copy without realizing that there's another copy buried elsewhere. Defending one copy against vandals and misinformed editing is enough work, and it doesn't need to be doubled, either. The material should be in one place, with pointers to it from other related topics. I think the material is fine here at Isotope, and can be readily found by readers interested in the topic of even/odd nucleons, etc.
Placing another copy into Atomic nucleus may "bulk up" that article, but it really is much more technical than the rest of the article, and may just scare off introductory level readers, who are more likely to look there first. I think that the Atomic nucleus article has enough to do, just to cover introductory material and an overview into the fields of atomic and nuclear physics. But it should only point to the more technical details, and not reproduce an arbitrary chunk of those details, which is not likely to be helpful to the general reader seeking a readable intro. Please think about what kind of reader is likely to look at Atomic nucleus, and what they are looking for there.
Summary: The Atomic nucleus article was a good introduction before, don't make it more intimidating by pasting in material of interest to specialists.
I won't get into the Isotope vs. Nuclide issue here, other than to say it's already been worked over, and I see little point in arguing it again. Reify-tech (talk) 23:44, 8 March 2013 (UTC)
Could you give links to relevant discussions? BTW learn that WP:consensus can change and any previous discussion does not form an ultimate solution. All this even-odd stuff has little relevance to the concept of isotope (i.e. to a nuclide in the context of its respective chemical element), end the material which is relevant needs refactoring to emphasise consequences for isotopes (not nuclides!). Incnis Mrsi (talk) 19:28, 11 March 2013 (UTC)
I am ready to settle on Even and odd atomic nuclei or so as a separate article. Incnis Mrsi (talk) 19:35, 11 March 2013 (UTC)
We may have to have that article (or something like it) anyway, just to list the various stable and primordially radioactive nuclides by parity. This article doesn't have lists except short ones (the small number of odd-odd's, for example). But these effects are of tremendous importance on natural occurance and stability of nuclides. For example, of the 22 mononuclidic elements that occur as just one nuclide in nature, 20 of them (all but Be and Th) are odd Z nuclides (they have an odd atomic number). Having an odd atomic number starts an element out with a tremendus handicap insofar as number of stable isotopes it's going to have. It fact, that one number is the most important predictor of that. Leaving this stuff out of the isotope/nuclide articles is not an option due to its explanatory power. Yes, I think the nuclide article should have all this stuff, but others didn't like that. Should we vote again? I vote move all this nuclide natural occurance stuff to the nuclide article. SBHarris 23:28, 11 March 2013 (UTC)
I agree that most of the material on odd-even should be moved to Nuclide, or if necessary a separate article. However since isotope is a better-known term than nuclide, many readers will come here first and not think to look at Nuclide. So I think that this article (Isotope) should have the key facts in a brief section, for example that both even Z and even A lead to greater abundance. At the beginning of the section there can be a See main article: Nuclide tag, to guide the interested reader to the rest of the material. Dirac66 (talk) 00:53, 12 March 2013 (UTC)
I was not involved in the Isotope vs. Nuclide debate, and don't have entrenched views on the subject. I am more interested in having clear, logical, and understandable coverage of these and related topics, and avoiding divergent, uncoordinated, overlapping coverage of related topics ("forking"). Given the hard-won consensus that Nuclide should focus on nuclear (rather than chemical) aspects, I agree that even/odd nucleon coverage more logically belongs there, especially since it can integrate better with the material there.
I'd also like to point out the article on Radioactive decay, which covers topics closely related to nuclear composition and stability, but seems to have developed somewhat on its own. See also Abundance of the chemical elements, Nuclear binding energy#Nuclear binding energy curve, and Semi-empirical mass formula, which relate to stability of nuclides. I'm not suggesting merging everything together, just that we be aware of related articles and how they might fit together, including introductory vs. advanced topics. I'm still very open to considering other ideas on organization of these topics, and would like to see coverage in this entire area a bit better coordinated and cross-inked. I'd like to find a subject roadmap, knowledge tree, or even an info bar covering this area, but don't know of any right now. If none exist, perhaps we could create at least an info bar, to give readers (and editors) a better overview of what's available here in Wikipedia.
Quick update, post edit-conflict... I pretty much agree with the specific actions User:Dirac66 proposes above. Reify-tech (talk) 01:34, 12 March 2013 (UTC)

A reminder that "forking" technically is a term for a no-no only when it's content forking (see WP:CFORK), where what is involved is removing info from one place and leaving no trace of it behind, so that the reader is unaware of that it exists and has no breadcrumb trail to follow. It's particularly deprecated in cases where there are two points of view (POVs) on an issue, and information on one "view" is removed entirely from the article on the other "view", so it is the POV that is forked. Some people have taken "forking" to mean that you can't have two articles on different points of view, but that also is wrong. You do it so long as they mention each other. For example, see Apollo program and Moon landing conspiracy theories, which both refer to the other. This is not a "POV fork." It's is CERTAINLY not a fork when related terms have their own articles, some of which overlap since the terms the things refer to, overlap. There is no forking involved in electromagnetic radiation, light, sunlight, although there is some overlap. And per WP:SS, of course broader articles have subarticles, like the varous types of radioactive decay, which all have their own (sub)articles, etc.

Again, it's also not against the rules when two articles have two exactly identical patches of information (although it's a bit wasteful of space). That is something like a webfork of WP, but that is not illegal. Indeed, since WP is WP:NOTPAPER, it's not a huge deal even here. However, in the name of efficiency, whenever we duplicate material, we should think of making one bit of it more or less long/specific/detailed, to fit the purpose for which we are using it-- that is all. But failing to do that, especially as a first pass, is not a mortal sin. WP:CFORK is the mortal sin, okay? All else in the way of exactly duplicating material in two artcles, is permitted, if discouraged for reasons mentioned.

Now: on a more general planning note, are we guilty of not making a perfect outline of knowledge before we embark on all this stuff? Hell, yes! WP is made as we go along, a bit like grandma's no-recipe cooking. Nobody knows enough to plan it all out beforehand, anyway. To write WP, you have to have a certain taste for jamming and improvization. If you're OCD and are driven crazy by improv, you should probably not torture yourself here. ;). SBHarris 03:13, 12 March 2013 (UTC)

Yeah, I have no problem with the wealth of different perspectives in Wikipedia, in fact I think it's a strength. Just looking for a better way to navigate and discover more of the related pieces that have developed here. Reify-tech (talk) 03:05, 12 March 2013 (UTC)

Isotope vs Nuclide[edit]

I don't agree with most of this section. In order of appearance:

1. "Atoms with identical nuclei belong to one nuclide,..." Atoms do not "BELONG" to a nuclide, they (each) ARE the same nuclide.

2. same sentence goes on:"...for example each carbon-13 nucleus is composed of 6 protons and 7 neutrons." ← this is true, but WHAT has it to do with the nuclide vs isotope discussion?? As far as I can see, NOTHING.

3. "The nuclide concept (referring to individual nuclear species) emphasizes nuclear properties over chemical properties, while the isotope concept (grouping all atoms of each element) emphasizes chemical over nuclear." ← This is my central objection. In my experience those discussing properties of individual atoms are more likely to use "nuclide", while those discussing properties of groups of atoms of that isotope are much more likely to use "isotope". It is simply group vs individual, NOT chemical vs physical, NOT nuclear vs atomic (or electronic).

4."The neutron number has large effects on nuclear properties, but its effect on chemical properties is negligible for most elements. Even in the case of the very lightest elements where the ratio of neutron number to atomic number varies the most between isotopes it usually has only a small effect, although it does matter in some circumstances (for hydrogen, the lightest element, the isotope effect is large enough to strongly affect biology)." ← This is irrelevant to this section and should be placed in lede, imho. Opinions?

5."Since isotope is the older term, it is better known than nuclide, and is still sometimes used in contexts where nuclide might be more appropriate, such as nuclear technology and nuclear medicine."← This confirms my objection to some extent. Can anyone cite a reference indicating that it is the AGE of the term that determines its use? I doubt it, I doubt this is correct. Different (sub-) disciplines tend to use their own terminology, not sure what age or popularity has to do with it.Abitslow (talk) 23:59, 2 November 2013 (UTC)