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Thorium

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I've listed this article for peer review because I'd like to take it to FA. I worked on it two years ago to GA-level and I would like to know what is still needed.

Thanks, Double sharp (talk) 04:53, 25 June 2016 (UTC)[reply]

Comments by Dunkleosteus77

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Comments below   User:Dunkleosteus77 |push to talk  18:00, 30 June 2016 (UTC):[reply]

  • I find ref no. 102 unreliable (The Straight Dope)
  • Use this convert to convert ISBN-10 to ISBN-13 as per WP:ISBN
  • not properly cited (most need an access date):
    • 1
    • 25
    • 29
    • 30
    • 75
    • 40
    • 56
    • 61
    • 70
    • 75
    • 85
    • 89
  • journals don't need access dates (like ref no. 47)
  • websites need access dates
  • ref no. 39 has a cite error
  • add |language=German parameter to ref no. 54
  • add |language=German parameter to ref no. 111
  • ref no. 56 is not properly cited
  • deadlinks:
  • duplinks:
    • uranium (in the lead and three times in the prose)
    • plutonium (twice)
    • electron configuration (twice)
    • coordination number (twice)
    • mass number
    • electronvolt
    • steel
    • Jöns Jakob Berzelius
    • cerium
    • oxidation state
    • lanthanide (twice)
    • protactinium
    • uranium-235
    • neptunium
    • uranium-238
    • uranium-233
    • tin
    • hafnium
    • scandium
    • yttrium (twice)
    • monazite
    • nitric acid (twice)
    • rare-earth element (twice)
    • pH
    • hydrochloric acid
    • gas mantle (three times)
    • hydroxide
    • electrolysis
    • Thorium tetrafluoride
    • isotypic
    • hygroscopic
    • monoclinic
    • alkali metals
    • ammonium
    • sulfer
    • nitrogen
    • phosphorus
    • arsenic
    • bismuth
    • hydrogen (twice)
    • oxygen
    • carbon (twice)
    • nitrate
    • carbonate
    • phosphate (twice)
    • neutron capture
    • uranium dioxide
    • transuranic element
    • ionium-thorium dating
    • age of the earth
    • tungsten
    • electron
    • cerium dioxide
    • alpha particle
    • pyrophoric
    • radon (twice)
    • radium
    • actinium

Tip: to highlight duplicate links, you can install a script (which actually means copying a small amount of text to a Wiki page), see Wikipedia:WikiProject_Birds/Tools--R8R (talk) 10:26, 1 July 2016 (UTC)[reply]

  • Use this converter to convert ISBN-10 to ISBN-13 (as per WP:ISBN)
  • ref no. 117 has a bracket after the access-date
  • remove the url for ref no. 72
  • ref no. 111 seems unreliable (The Straight Dope)

Review by R8R

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I'll review the article.--R8R (talk) 13:25, 3 July 2016 (UTC)[reply]

Disclaimer: the review below is my opinion on what I would do to improve the article. Possibly there are other directions. Mine, however, eventually yields a great article easy to read by readers (as I remember from comments by readers; we used to have a system for collecting readers' comments, where did it go?)

CharacteristicsBulk properties
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(I can't help but think I'd want to skip the subsection altogether. More paragraph breaks and a clearer structure could solve this problem.)

  • Why is periodic table location covered here? Atomic seems to be a better place
    • Well, mostly because for chemical elements, location is destiny. I confess I am unhappy about the structure with "chemical" so far from "compounds", but I can stomach it by interpreting "characteristics" as being a guide to Th the metal, while "compounds" to be a guide of what Th-containing compounds are like.
      • I've had the idea. I brushed it away by thinking the whole article is a key to the element. Besides, I don't have my books at the moment, but I think G&E or Ullmann also separate physical properties from chemical ones.--R8R (talk) 21:20, 3 July 2016 (UTC)[reply]
    • I had an idea (now implemented) of removing all the subheaders in this and making the order physical-atomic-chemistry. Isotopes is so huge that it might as well be a new section. Double sharp (talk) 16:04, 3 July 2016 (UTC)[reply]
  • I think all metals "can be cold-rolled, swaged, and drawn"
    • True. (Well, I guess not mercury.) So I have now added that this is entirely normal for all metals. (I suppose it makes sense to say because in my experience people tend to think of thorium and uranium as somehow different due to their radioactivity. They're really not. You can work with them just as you would with any other metal; it's just not a good idea for your health. There are no physical barriers that stop you, though.) Double sharp (talk) 16:04, 3 July 2016 (UTC)[reply]
      • I was still surprised after I saw you had that "can be cold-rolled, swaged, and drawn" and read your "True," but if some people actually think of Th and U as different from most other metals, than sure, the phrase can stay.--R8R (talk) 21:20, 3 July 2016 (UTC)[reply]
        • Never underestimate radiophobia, R8R! In real life I've met some people who were scared of my tritium watch... ^_^ Did you know that you can buy thorium rings quite legally? It would be such a fun way to mess with people, but it wouldn't be very pretty (neither would uranium) because it oxidises rather quickly in air. (Not that I would recommend putting it on outside this kind of demonstration. And I would probably invent some excuse to disappear into the nearest lavatory to perform the MSDS-recommended copious handwashing immediately afterwards. But the idea is enchantingly funny.) Double sharp (talk) 08:24, 13 July 2016 (UTC)[reply]
  • "The measured properties" you don't need to measure properties for them to be different
  • "Its density has been calculated to be 11.724 g/cm3" -- close to WP:WEASEL. Who made this calculations, especially since they don't match the reality? Are they even important? (There may be a reason, but it should be explicitly stated: "A simple TWOFG model [could be anything] suggests that the density of thorium should be ..., but it's actually .... The difference arises because...". Or maybe this should be skipped altogether)
    • The 11.724 value is what you would get by directly going from the lattice parameters. With elements like Re with incredibly high melting points, this could be easily explained by it being impossible to cast them in quantity, and sintering leaves microscopic voids. But Th's is not that high, so I do not know what the real explanation is. I've removed it; since Wickleder does not follow up on it, it must not be very important. Double sharp (talk) 16:04, 3 July 2016 (UTC)[reply]
      • Why, now that you explain it, it does seem to be catchy for me, at least. It would be great if you found an explanation; I'd be interested to read it as a reader.--R8R (talk) 21:20, 3 July 2016 (UTC)[reply]
        • I cannot find a better explanation, so I've used this one: it would nicely explain the variability of the experimental results. (Especially since no one would really care for Th; it's dense, but only about as dense as Pb. Double sharp (talk) 07:28, 4 July 2016 (UTC)[reply]
  • " However, thorium's melting point of 1750 °C is above both that of actinium (1227 °C) and that of protactinium (1562±15 °C): the melting points of the actinides do not have a clear dependence on their number of f electrons" -- but why does the difference exist in first place?
    • Well, there is a trend, it just only works from Th to Pu (the early, quasi-transition-metal actinides). Changed. Double sharp (talk) 16:04, 3 July 2016 (UTC)[reply]
      • Now that I've read the rephrased version, I think it can still be better.
      • "However, thorium's melting point of 1750 °C is above both that of actinium (1227 °C) and that of protactinium (1562±15 °C): there is a smooth trend downward in the melting points of the early actinides from thorium to plutonium where the number of f electrons increases from zero to six.[7]"
      • (If I am interpreting this correctly, then this could be rephrased to make smth. like) "Period 7, like other periods, shows a trend of increasing mp throughout early elements as their atomic numbers increase: actinium's mp is 1227 deg C, and, accordingly, thorium's mp is higher: 1750 deg C. At this point, however, a new trend of decreasing mp arises, as the 5f shell fills[a note here on why this actually affects the mp's would be great]: protactinium's mp is ~1560 deg C, and mp's further decrease up to plutonium.
      • A reader's note: "1562±15 °C" could be better if reworded as "~1560 °C", it just becomes easier to read. Also, in the original sentence you use the term "f electron," which you should wikilink to something relevant.
  • "Among the actinides, thorium has the highest melting and boiling points and second-lowest density (second only to actinium)" would be great to have the discussion on density and mp and bp and trends not scattered throughout one para
  • "The thermal expansion, and electrical and thermal conductivities of thorium, protactinium, and uranium are comparable and are typical of post-transition metals." first of all, thorium is not a post-transition metal, second, the sentence is missing an "and", third, this has to be a clearly distinguished discussion of periodic trends (a para dedicated to just that would be fine). By the way, what are thermal expansion and electrical and thermal conductivities of thorium, are these quantifiable? besides, "typical of post-transition metals" -- is this even high or low?

However, I am far from satisfied with this section as a reader (though it is becoming a little better, sure). I gave my initial ideas on reading the section, but I'd want to do more (similarly, I am not satisfied with Lead#Physical, except I haven't yet thought in detail on what I should fill it with). I'll skip it for now, because (unfortunately) I have not yet made my formula for a good section on physical macro-scale properties. I'll get back to it in the end of the review.--R8R (talk) 21:20, 3 July 2016 (UTC)[reply]

I will once again suggest to separate this [former Chemical subsection] from the rest of the section. You have a subtitle "Physical [properties]" and then you have a subtitles "Atomic" and "Isotopes", and both of these describe physical properties as well! Except what you have under the title of "Physical" describes bulk properties of thorium metal, and the other two describe atomic-scale physics, discussing electrons and nuclei, correspondingly. This would all go well under the title "Physical properties" (current "Physical" would best be called "Bulk"), and compounds would be described in a large section on chemistry (which does deserve a separate section in an article on what we call a chemical element).

How's the current arrangement? Double sharp (talk) 16:14, 3 July 2016 (UTC)[reply]
Fine! Looks fresh and very suitable for thorium. Isotopes as their own section are just fine for Th.--R8R (talk) 21:20, 3 July 2016 (UTC)[reply]

I planned to mention the metallic radius trend as well, but I decided against it as it's too complicated. You have to take into account that not only are the number of delocalised electrons making a difference, but also the differing structures (12-coordinated for Th, but 10-coordinated for Pa and downright irregular for U, Np, and Pu). This, I think, would be better left to the main article on the actinides. Double sharp (talk) 14:42, 16 July 2016 (UTC)[reply]


I have rethought this section and its organization and will write my ideas soon.--R8R (talk) 00:32, 14 August 2016 (UTC)[reply]

@Double sharp: I liked it when you immediately reacted to my comments; I felt the article was swiftly improving and getting closer and closer to its FAC. Yet response to my comments lost its momentum and can't get it back. Will it make sense for me to finish my review? The other remaining points directly rely on your actions (check list at the bottom of this page). I'll try to write down my ideas tonight but there won't be much left for me to do after that.--R8R (talk) 15:56, 16 August 2016 (UTC)[reply]

Comments as promised.

First of all, we should probably leave the introductory para as is and be fine with it. It's okay, actually.

The next thing to come to my mind would be allotropy. Allotropy actually greatly affects what you describe thereafter (carbon being graphite and diamond being the best example of this). You say something like "thorium only has one allotrope, which is fcc, and it remains fcc until it'a as hot as ... deg C (... deg F, ... K)" or the like. You can probably also describe the stuff like thermal expansion (which is related anyway to lattice parameters, which should also mention) here. Come to think of that, that doesn't exactly fit the title, but then again, make title follow your story and not vice versa. Maybe go with "Mechanical properties"? Then I noticed you had a table; this can be converted into text.\

Hmm, carbon (and tin) are kind of special cases here. Everyone knows graphite from pencils and diamonds from overpriced jewellery; the β→α transition in tin is pretty well-known (tin pest and bursting organ pipes). But of thorium's two allotropes, only the room-temperature one really matters to the average chemist. Does anyone care about the low-temperature hexagonal close-packed allotrope of sodium, for instance? Also, these transition temperatures change greatly with impurities. Double sharp (talk) 10:31, 31 August 2016 (UTC)[reply]
Why wouldn't you say that? "At r.t., thorium is <some form>. Its parameters are blah blah blah. On extreme cooling, it forms a <another form> form, but nobody really cares. Impurities greatly affect allotropy of thorium: example, example."

Then follows a para with stats like density, mp, bp. It would be good to explain why thorium has high values of these paramenters (and this is crucially important). Bulk modulus suits here as well.

I might do a solution like we did at Pb for this, explaining how the [Rn]6d27s2 configuration leads to all this. This is an interesting one. I'd have automatically expected covalent bonding on top of metallic bonding to be the reason, like W, but that can't be right because Th doesn't have a high tensile strength (which would also be raised like W). Didn't I also just say in the article that the reason was because there wasn't much 5f/6d hybridisation in Th (unlike what you get in U), which leads to directional bonds instead of non-directional metallic bonding? Double sharp (talk) 10:31, 31 August 2016 (UTC)[reply]

"Thorium can also form alloys with many other metals." two questions. 1) is it not true for all metals? 2) if you want to specify thorium solves/is solved in other metals and doesn't form copper-lead-like alloys (if this is even the case), do so. Also, the amount of info on this is inadequate. If people actually alloy with anything, then you need more (solubility in metals, for example). If they don't, then a general note in the intro para should be enough.--R8R (talk) 13:37, 17 August 2016 (UTC)[reply]

Yes, people actually do this. Adding small quantities of Th to Mg metal improves its mechanical strength (ref from Gmelin, though I have to wonder how common this use is today). Th-Al alloys have been suggested as a way to store Th in Th reactors. You get eutectics with Cr and U. Th does not really dissolve in other metals except its "little sister" Ce. (Will add!) Double sharp (talk) 10:37, 31 August 2016 (UTC)[reply]
Isotopes
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I'll continue from here.--R8R (talk) 21:20, 3 July 2016 (UTC)[reply]

As general advice, I'll suggest paras a little shorter when possible.

  • "Although X, Y; however" this could be reworded
  • "considerably longer than the age of the earth" how much is "considerably"? We're even thinking in log scale when it comes to half-lives. "Almost three times" would be fine.
  • "with more than 83 protons" how did 83 get into this? Since you're writing a detailed section anyway, a little (just a little) context would be fine. ("All elements (except for technetium and promethium) up to bismuth, element 83, are practically stable for any purpose[1], but from polonium, element 84, on, all elements are unstable. Of all isotopes of these elements, thorium-232 is the most stable: its half-life is ..., almost three times as long as the age of the Earth and even a little longer than that of the universe." how's that sound?)

[1] -- by the way, I like how you said "its half-life is so long that its decay is negligible even over geological timespans" in a note; except why is geology important here?

That's about Bi. The idea was that the decay of Bi is negligible, so there is about as much Bi left as there was at the formation of the Solar System. However, with Th and U, we know that what we have left is but a lower fraction of what we had 4.5 billion years ago. Double sharp (talk) 07:20, 4 July 2016 (UTC)[reply]
I got it. :) I just liked that new way to describe how long its half-life is. This bothers me every time I have to say smth. about what elements are stable, because Bi is practically stable, but theoretically not! It's certainly better than "super-long" or "so long it can be stable for any purpose" and maybe even a little better than "many orders of magnitude longer than the age of the Universe."
  • "However, in deep seawaters the isotope 230Th" we were having a nice introductory talk, and now we're for some reason going into deep seawaters. Since you're discussing isotopes and not geology, this can wait until later. So can the acknowledgment of this second isotope by the IUPAC. Besides, the next para also begins with Th-232! So why break that story by deep seawaters?
  • "the last "classically stable" nuclide" even the text acknowledges this is a somewhat original term. Since we're not a book oriented at pros, we could use a note here, or just reword this somehow. Jargon scares people away and this is an encyclopedia for and by everybody. Actually, I think it would be great if you merged the first half of the first para and the first half of the second para into a new para.
  • "By geographical analogy" took me a second to understand it. "by analogy with geographical objects(?)"? (also, please, lose that "therefore") The whole analogy would be either contracted or put into its own para, if I were to write this. Also, there is a cool 3d pic of the island of instability that would very well illustrate the idea.
  • personally, I don't insist, but some reviewers ask to display short descriptions near names, so "Yuri Oganessian" becomes "Soviet/Russian physicist Yuri Oganessian" and the like
  • "This geographic analogy has often been used by pioneers of superheavy element research, such as Yuri Oganessian, and is the origin of the term island of stability." This whole sentence made me think again if the analogy is even needed. We're only at element 90, after all?
    • Well, the reason I put this sentence in was so that it would be obvious that this analogy was not OR. I've relegated it to a footnote, since it feels very tacked-on.
    • As for why the analogy is here, it's because Th and U are widely considered to be an "island of relative stability", as you will see if you look at the half-lives of the trans-lead elements: you can see this in all those island-of-stability pictures too. See this for example. Double sharp (talk) 07:20, 4 July 2016 (UTC)[reply]
      • Hmm. I see that the term still is more commonly used for the superheavies even with that "relative" (and one source refers to, unexpectedly, Iran and something about oil(?)). I suggest you move all of that into a long note. Or best skip altogether, this feels not relevant here. I just took another read---yes, this feels not needed, since Th is element 90. This could be revised twenty or so elements later.--R8R (talk) 10:25, 4 July 2016 (UTC)[reply]
        • The main reason I want to say it is so that I can talk about this region around A = 230–250 and Z = 90–96, give it a name (as two of those search results do), and say why it should be singled out for stability (again, shell effects). If not you would expect it to be like Po and Rn; the strong force can't reach all the way across, so bits fall off (alpha decay) until it's small enough that this is possible (reaching Pb or Bi). But with Th and U, we are completing a nuclear shell, so this alpha decay is inhibited. Double sharp (talk) 12:14, 4 July 2016 (UTC)[reply]
          • >"as two of those search results do" but that's two! You see, there is a reason why it's only two results :) you don't need a special term to discuss something, you can just say "thorium to (around) curium" or the like. You don't need to have a para of poorly relevant talk to just invent a synonym which is, by the way, ambiguous, as the Google Books search results tell.
          • So am I correct in that the struck text is just introductory talk?
          • The line of stable nuclides, that is mostly continuous from hydrogen to lead (with breaks at technetium and promethium), plummets immediately after bismuth with its extremely long half-life of 1.9 × 1019 years. The next element, polonium, has a half-life of only 130 years (209Po), and there follows a three-element gap of extreme instability where the longest-lived isotope, 222Rn, has a half-life of only four days.[9] (this, by the way, has partly already been covered in the previous para) By geographical analogy, bismuth is at the shore of the continent of stable nuclides, with a following strait of instability centered on radon. A continental shelf continues, nevertheless: shallows begin to appear at radium, with a half-life of 1600 years, that rise to form significant islands towering over the sea at thorium and uranium, forming an archipelago with the lesser islands at the actinides neptunium, plutonium, and curium which have half-lives of millions of years. The islands then recede back into shallows by californium (half-life 900 years), and by the end of the actinide series the open "sea of instability" yawns before the shore, where the mutual electromagnetic repulsion of protons finally cannot be overcome, and the nuclides quickly succumb within a few milliseconds to spontaneous fission.[12][13][d] The reason for the existence of this "island of relative stability" around thorium and uranium is because the most stable isotopes of these elements have closed nuclear shells;[14][15] nevertheless, since thorium and uranium have more protons than lead and bismuth, their nuclei are thus still susceptible to alpha decay because the strong nuclear force is not strong enough to overcome the electromagnetic repulsion between their protons.[16]
          • You won't lose anything if you just say something like "Since thorium and uranium have more protons than lead and bismuth, their nuclei are thus still susceptible to alpha decay because the strong nuclear force is not strong enough to overcome the electromagnetic repulsion between their protons. However, they have closed nuclear shells: this is the basis of the stability of both elements. (since you described that in the previous para)" (also, this could use some details, but that could be hardcore physics, so I can't tell; still, are these available?). You're not writing actinide, you're writing thorium.--R8R (talk) 12:43, 4 July 2016 (UTC)[reply]
            • OK, cut the introductory material: you make sense. It is also not quite agreed on how far this "island" should extend: it seems from those two books that Th and U are the main things, and Np, Pu, and Cm are only getting the benefits in a horseshoes-and-kisses kind of way. So I made it talk about only Th and U, the only two primordial radioactive elements. Double sharp (talk) 13:05, 4 July 2016 (UTC)[reply]
  • "bare critical mass" this is surely wikilinkable to something relevant. Besides, could you make it half a sentence longer to it would be easier to understand? (I remember what we're talking about from physics at school, but surely not everyone paid attention back then)

In general, a nice section.--R8R (talk) 21:55, 3 July 2016 (UTC)[reply]

  • "recently" is relative
  • a tip: for the first mention, it is always best to spell out any acronyms. ("IUPAC" in this case.)
  • "The isotope 229Th has a nuclear isomer (or metastable state) with a remarkably low excitation energy,[16] recently measured to be (7.6 ± 0.5) eV.[17]" This sentence seems a little out of place. Either a small introduction of half to one sentence or leaving it out (which I prefer at the moment) will do.--R8R (talk) 10:33, 4 July 2016 (UTC)[reply]
    • I separated it out, adding a brief intro like the other element articles about Th also having 3 meta states. Now the reason I mention this – and I can't believe I forgot – is that this is actually so low that if it underwent isomeric transition, the gamma ray emitted would be in the UV range! (Added this.) Double sharp (talk) 13:11, 4 July 2016 (UTC)[reply]
  • ".[9][10][11] 232Th" I strongly suggest starting that sentence with an actual word, so the superscript numbers don't stand next to each other.

Each time I think "you're [that is, you, DS] doing doing great job, I can stop now," there's also something else to improve. That's good for the article, though. :)

  • " for example, the densities of 228Th, 229Th, 230Th, and 232Th in g/cm3 are respectively expected to be 11.524, 11.575, 11.626, and 11.727." now wait a second, we've talked about the density, and we had a value of 11.724; I am confused (I am not, but I could be)
  • "232Th, the most common thorium isotope" we already got it, thank you, no need for repetition
  • "(The remaining natural thorium isotope, 229Th, occurs in minute traces as part of the decay chain of 237Np, the neptunium series, which is much less abundant than the other decay chains in nature and was hence discovered much later: therefore it does not have a historical name.)" parentheses not really needed here
  • (a thought; no action required) I keep wondering how the future improved History section will interact with the part on history of the isotopes

otherwise the section looks great! except a few comments are still waiting to be completed (like that IUPAC one).--R8R (talk) 13:50, 4 July 2016 (UTC)[reply]

Regarding exactly what happens beyond Bi: here's my totally-not-expert guess at a bird's-eye-view of the nuclides chart. If you look, alpha decay starts to infect the light isotopes of Te–Xe, and then it assaults some of the early lanthanides (all "stable" isotopes of Sm and Eu should undergo it). Then it sneaks up at the proton drip line in the 5d transition metals, and its reign rapidly expands until the magic numbers can no longer save you past Bi, and at Po it erupts and takes over, driving out poor electron capture. Then if you look at the lines of beta and alpha stability, you see the horrible truth: they diverge from each other past the magic number effects culminating at Pb. So if you look at 232Th and 238U, they are actually close to the heaviest isotopes of these elements we know (238Th and 242U). They get a magic number boost, but everything around them dies quickly of beta emission. Then we face another attack on the beta-stability line by spontaneous fission from 250Cm onward, and the island comes to an abrupt halt. (I may be totally wrong about this.) Double sharp (talk) 14:28, 4 July 2016 (UTC)[reply]

  • Why is radiodating added? of course, it is related to isotopes, but is it a big thing? I think that hardly a brief mention is enough (check, for example, Lead#Isotopes and how radiodating is mentioned there).
    • Well, I only have one paragraph, and it seems to me that it follows how we mentioned earlier that 230Th and 232Th are the only two important isotopes of thorium in nature. (Also, I think isotopes and radiodating are more important for Th and U than for stable elements. For example, the 238U:235U ratio has changed substantially over time because of the shorter half-life of the latter.) Double sharp (talk) 10:43, 31 August 2016 (UTC)[reply]
It's the position I would stand on, but I won't argue as long as you're confident in your choice.--R8R (talk) 15:49, 1 September 2016 (UTC)[reply]
History
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I'll continue from here.--R8R (talk) 13:52, 4 July 2016 (UTC)[reply]

Isotopes has been done pretty fast (and I think we have a quite good section as a result), but this relied on two factors: first, it already had most of the info and second, you are quite familiar with that topic. We'll probably lack either one here. Luckily, I've had my time to think how to improve this section and make it a showcase.

This is the best section to read and write because most terms it operates with are easy to understand: take a mineral, no sign of what we had known before, industry and factories, etc. Any reader should get this one easily. As a writer, I see my job in that the text is interesting to read for a layman and that it is both interconnected and connected with other sections. Physical characteristics, chemistry, occurrence, history, uses---all of these are very interrelated and tell the story of a single element; when that interrelation is underlined, the text is interesting to read: the reader sees some conclusions, the text makes him think a little (but not too much so most people aren't scared away). That's why sometimes you need to explain some terms that may seem easy to you in a footnote, for example. Maybe you'll get them into learning something else on the matter. At best, they should leave after reading your article feeling smart. If you got that, that your job is very well done and people will want that translated into Spanish ;)

This, again, relies on two important principles: introducing reader into some possibly unknown before concepts (they may get interested and do further research themselves) and interconnections within the text (so the reader sees why A follows from B, which is sometimes quite obvious, but most people don't know something or have never given it a deep thought, or were just missing something obvious. If the reader understands the logical implications, congrats, well done). (I rarely actually think in such terms, but I think that's what my writing breaks down to. Maybe I forgot something as important; this is an improvised comment.)

Now, back to this section. On reading it, I see lots of potential far from achieved. The part on radioactivity is related to Isotopes, the part on uses is related to Uses, categorization is related to chemistry, etc. Also, these side stories are interrelated: most obviously, radioactivity has affected the uses of the element.

The section used to have two subtitles: Discovery and After discovery (was called something else; doesn't matter what, though). This reflects a problem within the text: it clearly falls into two parts, which didn't even rely on each other. Most interestingly, radioactivity, uses, and categorization weren't (still aren't!) even put into a straight relationship, while they have been affected by each other. We're going to improve that.

(And I'll leave it here for a while. Hopefully I'll continue soon/tomorrow.)--R8R (talk) 22:05, 4 July 2016 (UTC)[reply]

As a general note, I strongly suggest the story goes chronologically, not divided into sub-topics. Something like "erroneous discovery--actual discovery--Mendeleev--industry--radioactivity--changes in industrial demand for thorium--Seaborg--atomic weapons--nuclear power," except there could be intermediate events of lower significance.

This will require some research :( if I have time during the weekend, I'll try to research along.

The first para is okay, but that's it. I re-read ununseptium#History for inspiration, and yes, there it was!

  • "In 1815, the Swedish chemist Jöns Jakob Berzelius analysed a mineral from a copper mine in Falun, central Sweden" now that I've thought about it for some time, why did he even do that? what was his goal? he didn't just randomly take a rock and analyze it, right?
  • "Assuming that a new element was contained in the mineral, he named..." think this could have been written more interestingly: "After the analysis, he was not able to match a correspondence between [what, by the way? what was the analysis technique?] of that mineral and those of any known elements; as such, he suggested that the mineral contained a new element, which he named..."
  • "However, ten years later, he retracted his findings, as the mineral in question proved to actually be an yttrium mineral" was he the first to realize he'd made that mistake, or did someone point him to that?
    • According to the Fontani reference, he was very cautious about the 1815 discovery, as he was himself unsure. (Apparently he did not even announce the name "thorium" in the paper; given that Wickleder and that old great source Weeks both give it, presumably he did not release the name, but may have written it down in his laboratory notebooks as a good idea for an element name.) Unfortunately many of the secondary sources are frustratingly vague about all of this, and I cannot really access Berzelius' notebooks myself to do original research! Double sharp (talk) 13:33, 7 July 2016 (UTC)[reply]
  • speaking of which, why did he even make that mistake? was there a specific reason?
    • No idea, but he was not really sure himself, as I said. (He had earlier been involved with another false discovery, gahnium, which turned out to be nothing more than zinc oxide. He was in his mid-twenties and was just flush from the success of discovering cerium, and was not careful enough: no doubt he learned from his mistake, and that was why he was so cautious about the 1815 "discovery", not even giving it a name in public, as if he did not have complete faith in it.) Double sharp (talk) 13:33, 7 July 2016 (UTC)[reply]
  • "the mineral was named kenotime" but that happened after 1825? what was the mineral referred to between 1815 and 1825? genuinely curious. and who came up with that name?
  • "In 1828, Morten Thrane Esmark found a black mineral" and what led to that? again, really want to know
  • "The elder Esmark was not able to identify it" think this could produce a few sentences and make more good prose, but I don't know what analysis technique he used/how long did he even try/did he even know Berzelius/why didn't he just made that conclusion himself? (the answer to the last one is that he probably wasn't even sure about that, but I'd love to know; I'd want to see answers to these questions in the text.)
  • What analysis technique did Berzelius use this time?
  • "In 1828, Morten Thrane Esmark found a black mineral [...] published his findings in 1829." such close dates, these could use months or at least seasons (if months are not available)

I'll leave it here for now. As a general note, try to provide as many details as you can. You'll lose ones you won't need anyway.--R8R (talk) 19:58, 5 July 2016 (UTC)[reply]

  • One more for now: how long did it take to get Th recognized as an element by everyone? Nowadays, we have IUPAC that is sort of the ultimate judge, but there was none back then. Did anyone use the idea that that "thorium" of 1815 was an element? How long did it take for that idea to catch up after 1829? (It's hard to say if someone would use that knowledge anyways if nobody contacted the element and there wasn't a full-scale periodic table yet without researching. If that's the case, still mention that in the text; it will compliment the later parts on Mendeleev's and Seaborg's tables)
    • I don't think anyone would've doubted it the second time, after Berzelius could hold a sample of (admittedly not very pure) thorium in his hands: he was very respected by that time. The first time, given his own uncertainty, people must have doubted. But annoyingly I cannot find a source for their reactions: it does not seem like the sort of thing that would have been recorded! Double sharp (talk) 16:09, 8 July 2016 (UTC)[reply]
  • Speaking of Mendeleev, it would be cool to briefly mention (maybe even in a note) if thorium was included into other tables of mid-19th century. Also, it'd be nice to mention that Mendeleev's didn't get recognized immediately, which makes adding info on other tables even more relevant.--R8R (talk) 07:29, 6 July 2016 (UTC)[reply]
  • "While cerium was soon removed from the main body of the table and placed in a separate lanthanide series, it was not until 1945 that Glenn T. Seaborg realised..." if I were to write this, I would definitely leave that util we move to 1945. When you give the story and make it follow the chronological order of events, it is quite natural to introduce concepts in the order that they appeared. If you mention that 1892 idea in the main text, then introduce the concept at that moment. If you leave it in a note, then mention it when Seaborg rolls into the story. (By the way, the 1892 note looks absolutely cool. This is kind of a detail I'd want in a FA of mine.)
  • Also, I'd move the isolation (which is, by the way, a nice addition) to a new paragraph that is located per Th's chronology, given we're talking about a 1914 event. I'd start it like "Although Th was discovered in 1829, it wasn't isolated at that point; and either nobody even tried before the 19th century or nobody succeeded (depending on what the actual case is; if there were attempts you can find, please add them). For the first time, Th was isolated by a XXXian physicist(?) D. Lely, Jr. [this man is tougher to google than you'd expect; please spell out the names] and and YYYian physicist(?) L. Hamburger in 1914. They performed the isolation using ... and described some basic properties of thorium metal."
    • I am really not hopeful at finding their names: even their original paper describing their results doesn't spell them out, and nobody who cites them thereafter spells them out either. But I did at least find out their method (now to be included). Their real accomplishment was the isolation of 99%-pure thorium, as while others had tried earlier, there still remained significant Ce and U impurities that went unnoticed because of their similar chemical properties (particularly ThO2 vs. CeO2 and UO2). Double sharp (talk) 12:22, 7 July 2016 (UTC)[reply]
      • What I would do now is to write directly to Zeitschrift für anorganische und allgemeine Chemie and ask them if they could help spell out the names. They have their archives, surely they can help. (If you don't do it in a few days and signal as such, I will.)--R8R (talk) 08:00, 8 July 2016 (UTC)[reply]
      • The End of the Artkle gives a place of work of the two authors: Eindhoven, Holland, Chemisches Laboratorium der Philips’ Metall- Glühlumpenfabrik A.-G. (Chemikal Laboratory of the Philips Metal-Lightbulb-Factory- AG)--Stone (talk) 19:57, 24 July 2016 (UTC)[reply]
  • "The space thorium formerly occupied in the periodic table under hafnium is now occupied by the transactinide rutherfordium.[41] Today, thorium's similarities to hafnium are still sometimes acknowledged by calling it a "pseudo group-4 element"." this would be more suitable in a note
    • I'd put the first sentence in a note, indeed, since it is more about Rf than Th. Nevertheless I am not so certain about relegating the second that one, because it does illustrate how similar Th is to Ti, Zr, and Hf, and how useful that classification is. Really, if you only look at Th, Pa, and U, they are far more like transition metals than lanthanides: group 3 cannot really fit these three actinides well (if you use the 15LaAc interpretation of the table), because of their maximum and common +4, +5, and +6 oxidation states respectively. (In fact, I believe this was still a matter of controversy at the time of the beautiful Soviet popular-science book I linked to you – look for "Where is Thy Place, Uranium?" ^_^) Double sharp (talk) 12:22, 7 July 2016 (UTC)[reply]
  • There's little left to describe in this section. Want to know much more about the uses. Nuclear weapons and energy are absolutely missing. "In the early history of the study of radioactivity, the different natural isotopes of thorium were given different names. In this scheme, 227Th was named radioactinium (RdAc), 228Th radiothorium (RdTh), 230Th ionium (Io), 231Th uranium Y (UY), 232Th thorium (Th), and 234Th uranium X1 (UX1).[18] This reflects that 227Th and 231Th occur in the decay chain of natural 235U (the actinium series), 228Th occurs in the decay chain of 232Th (the thorium series), and that 230Th occurs in the decay chain of 238U (the uranium or radium series)." -- think this belongs here, except needs to be re-written into a nice story: after you mention the first discovery of radioactivity, it generally makes sense to say something along the lines of "Research on radioactivity sparked like fire, and many new nuclides have been found that received their own names: ... At one moment [say when], however, it became apparent that all of these were isotopes of the same element as the nuclide that was at that time referred to as "thorium" [Th's only natural one, 232Th]. As such, they were "combined" into a single established element 'thorium'." (the wording could've been better, but you get the idea.)--R8R (talk) 09:55, 7 July 2016 (UTC)[reply]
  • "Meanwhile, Niels Bohr's theoretical model of the atom and its electron orbitals indicated that the seventh row of the periodic table should also have f-shells filling before the d-shells that were filled in the transition elements, like the sixth row with the lanthanides preceding the 5d transition metals." does it? I am not familiar with Bohr's original work, despite the popularity of the concept in general. Did Bohr really (even if indirectly) predict the 5f series?
    • Yes, he did! (His table even has blanks after uranium, and he explicitly notes that 118 would be the next noble gas after radon! How cool! But not for this article, of course: but I suppose it would make a good addition to the 118 article that Bohr was the first figure to take the possibility of such a high-numbered element seriously, a few years before Charles Janet and his table that extended to 120.) However, while he did think that 5f should fill and make row 7 as long as row 6, he looked at the chemical properties of Ac–U and inferred that 6d and 5f would have crossed energy levels, and that 5f should not start being occupied favourably until Pu. So he seems to think of Th as a 6d element, but correctly placed it under Ce in his table. Double sharp (talk) 09:08, 8 July 2016 (UTC)[reply]
  • " This occurs because the 5f orbitals are then relativistically destabilised and delocalised and are thus able to participate in chemical reactions to an extent similar to the d-electrons of the transition metals." sure, but it's a distraction from the main story, let's put it into a note
  • I've thought about it for some time. One thing I'd want to get implemented is to treat the 20th century improvements as further development of the atomic theory. So I imagine a para starts off like "In the late 19th/early 20th century, the atomic theory has been significantly expanded and new concepts within were discovered. In 189X, someone first observed a thorium sample to exhibit radioactivity in only Y months after the concept was first formulated and add a few of sentences on that, including the decline of Th usage since then(?), I'd also add a phrase like "the newly discovered radioactivity sparked further research on atomic nuclei" somewhere; then the Bohr model; the actinide concept; radioactivity used in the atomic bombs and nuclear reactors. Unfortunately, the isolation of metallic thorium chronologically falls between Curie and Bohr, but since this is a minor fact for thorium anyway (compare with fluorine), I think you could move it to the end of para on the actual discovery and treat it as a minor fact, which it is. ("After the discovery, however, thorium has not been isolated for a long time; the main challenge is not to reduce the thorium ion, but to separate thorium from the accompanying rare earth metals [please add this remark!]. Someone tried that in 1892 and failed; the actual isolation happened in 1914 by X and Y [have you written to that German journal yet to get their names, or should I?]. In 1927, someone else made further improvements to the purification process, obtaining even purer thorium")
  • The same comment, generalized: Since what happened around Th in the 20th century happened within a very remarkable and easily distinguishable topic of radioactivity, it's a great idea to try to make that theme resounding throughout the description of that period.--R8R (talk) 09:56, 11 July 2016 (UTC)[reply]

The section is now in a good shape. Two things I'm bothered with are: 1) we don't cover the phaseout of Th in non-nuclear uses well, and 2) we completely neglect nuclear weapons and reactors. But we'll remember these are missing and I'll move to the next section for now, supposing these will be fixed later.

That 2006 source says that the phaseout of Th in non-radioctivity-related uses intensified in the "last decade." I am genuinely interested why only in the nineties? Radioactivity and its effects on health have been known for a few decades by that moment. Radium girls won their first case in 1928, for example.--R8R (talk) 16:13, 20 July 2016 (UTC)[reply]

Here's how I would want to organize the info on the phaseout: I'd say in the para about 1885 nothing about radioactivity yet (we introduce the reader into radioactivity later); then, when we do introduce the reader into radioactivity, add at the end of that para than thorium yet remained in use, but now hazards were known (can you find a ref to say they were known by the thirties?) and a search for safer replacements began. And then a separate para located with accordance with general timeline that Th was finally phased out in the nineties because there were decent alternatives now.--R8R (talk) 18:20, 23 July 2016 (UTC)[reply]

  • "In the 21th century, thorium's potential for improving proliferation resistance and waste characteristics led to renewed interest in the thorium fuel cycle." this is a very empty sentence. can we cover this in a closer detail?

also, @Double sharp: as you haven't appeared here for a while. I'm done with my first go through the article; I am now left to do what I skipped and marked as skipped.--R8R (talk) 20:59, 8 August 2016 (UTC)[reply]

Occurrence
[edit]

I haven't actually read the section yet, but there's a comment I want to give out right away.

I'd been thinking about it for some time until I realized the best order of section generally is: Physical (usually with two subsections, Bulk and Isotopes, which separate sections here; this makes no difference) -- Chemical -- Occurrence -- History -- Production -- Uses -- Bio/Precautions. Physical is the most general section of all, and it may help explain we'll read later. Then chem, also general and related to phys; then occurrence (which will benefit from the context by Isotopes for formation/stars and Chem for terrestrial occurrence). Then history, which probably will benefit from occurrence. Then production, usually related to history. Then Uses (makes sense to put those directly after Production). And then Bio as a great way to end the article. (I also think that the current Chem is too large, but I'll come to that later.)--R8R (talk) 12:32, 19 July 2016 (UTC)[reply]

One comment specific for this section: I suggest making this section divided into two parts, Formation/In space and On Earth. The first one can tell how Th was formed, in what stars can be found, etc. The second one can start off with Goldschmidt and then move to terrestrial occurrence. I tried that in fluorine and lead, and it worked both times. Now the content looks not structured well, and this should line things up.--R8R (talk) 21:09, 19 July 2016 (UTC)[reply]

Another general comment: there are many nice facts in this article (like really nice) that are not really related to thorium. I first noticed that when I saw there is note [x]. X is the 24th letter in the English alphabet. There are notes which provide superfluous info, as cool as it is. (I'll review notes separately later.) This is also sometimes the case for the prose part: you add cool facts, but then they distract you from the main story and you have to re-concentrate on it again. (Again, this is a general comment; I am not sitting in front of a computer and thus it's difficult to search for examples. I'll try to drop a word in ten hours or so.--R8R (talk) 10:34, 21 July 2016 (UTC)[reply]

I've got another spare minure: here are some comments.

  • the first half-sentence is bad. "Th has been around for >4.5B years (link to age of Earth), being older than the Earth." so... How long exactly has thorium existed? What does the Earth have to do with this at this point if you then talk about dying stars?
  • Immediately after this introduction, I'd move to the how of Th formation (the r-process; also, you don't need to mention the other processes since they're not relevant here), and then to the where, and then to general statistics (ppm in the Universe, etc.)--R8R (talk) 10:58, 21 July 2016 (UTC)[reply]
    • Edited. Now I just talk about the r-process alone and why it is the only one for Th, implying that it is only made in supernovae. I also notice a cool fact that Th is almost as abundant on Pb on Earth, but is far less abundant in the Universe; where should I add that? (Seems to straddle both sections.) Double sharp (talk) 16:35, 21 July 2016 (UTC)[reply]
      • The Earth is a part of the space, so first the intro (Formation) and then the specifics (Earth and anything related to it). So I'd probably put it in the second subsection. (Why is that, by the way?)--R8R (talk) 20:48, 21 July 2016 (UTC)[reply]
  • "On Earth, thorium is not a rare element as was previously thought, having an abundance comparable to that of lead and molybdenum, twice that of arsenic, and thrice that of tin.[71] In nature, it occurs in the +4 oxidation state, together with uranium(IV), zirconium(IV), hafnium(IV), and cerium(IV), but also with scandium, yttrium, and the trivalent lanthanides which have similar ionic radii.[71] However, thorium only occurs as a minor constituent of most minerals.[71] Soil normally contains about 6 parts per million (ppm) of thorium.[72]" I'd dedicate a para to relative abundance alone so you don't mix different topics. "Th is not a rare element[vague, pls find a better wording], even though it was once thought to be rare [why, if possible], having an abundance of ... ppm. That is comparable to that of lead, despite lead being a lot more common in the universe. This is because..." and then have the next para start off with "occurs in +4 state with U, Zr, Ce, Ln, etc..."
  • "Thorium minerals occur on all continents.[38][73][74]" isn't this true for every element? do you need to even state the fact, let alone give three references?
  • "Thorium is several times more abundant in Earth's crust than all isotopes of uranium combined and 232Th is several hundred times more abundant than 235U." I think Th is a worthy element on its own and it doesn't need so many comparisons with uranium and we can safely cut this fragment.
  • "Because of thorium's radioactivity, minerals containing significant quantities of thorium are often metamict, their crystal structure having been partially or totally destroyed by the alpha radiation produced in the radioactive decay of thorium.[75][n]" very cool fact. but again, that note [n] is not needed here for the same reason
  • also, I still don't know, does Th occur in the crust or where?
  • "specific gravity" why not just use "density," and why is that relevant?
  • "Because India has one of the largest supplies of thorium in the world (accounting for about 30% of known thorium reserves), but does not have much uranium, India formulated a nuclear power programme based on the thorium fuel cycle with the goal of achieving energy independence.[79]" belongs elsewhere
  • "It is especially common in the Tamil Nadu coastal areas of India, where residents may be exposed to a naturally occurring radiation dose ten times higher than the worldwide average.[78]" probably same here
  • "and the name of the mineral changes according to the ThO2 content.[71][o]" that's one case where having a note about uranium is justified (no action required)
  • what is the purpose of the table with relevant occurrences? as of now, the first thing I see is that lead is abundant, but it should be something about thorium, right?
    • It's a little hard to make this point with the numbers; a graph would work better. (Though I'm not sure how good the current replacement is.) I'm not really sure what I should be comparing Th with, actually, other than U, because everything else gets produced in multiple ways. Double sharp (talk) 11:50, 22 July 2016 (UTC)[reply]
  • " This is because thorium, being a lithophile, is likely to form oxide minerals that do not sink into the core, unlike the platinum group metals that are more abundantly produced by the r-process.[70]" I don't understand (I actually don't, please explain here), why is this the reason?
    • Now that I think about it, this isn't actually a complete explanation. Okay, so while the r-process would give you lots of late 5d transition metals and very little Th, the fact that Th stays on the surface while the 5d transition metals don't means that you see more Th on Earth. This is fine, but it doesn't really seem like it explains how Th somehow becomes as common as Pb on Earth. There is a big jump there, as you can see if you look at the graph! I will keep looking. Double sharp (talk) 12:43, 22 July 2016 (UTC)[reply]
  • "odd-numbered" I suggest explaining in a note (which you're free to take from lead) why that even matters
  • "and of these only tantalum is also less abundant than uranium, being in fact the rarest element in the Solar System" not relevant here. Sure, there are many nice facts about what's around thorium, but most of them don't belong here since you're writing an article called thorium. This, again, is problematic because each time when you go into a sub-story, you are distracted from your actual story, and straying from it many times complicates reading. Priorities first. To generalize this, if there are relevant details not necessarily fit into the main body of an overview article, you (maybe) can leave it in a note; if it's a cool fact not specifically relevant, you're better off leaving it out.--R8R (talk) 10:32, 22 July 2016 (UTC)[reply]
Chem
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This section is so long. So long.--R8R (talk) 10:58, 21 July 2016 (UTC)[reply]

Part of the problem is the opening, which is where I am trying to set the stage for the properties of Th, but instead ends up rambling all over the place now that I look at it. Similarly to the way you give an introductory primer on Pb in that article, I would think that the most important aspects that should be taken away by the reader about Th's chemistry are (1) it is practically always in the +4 state, giving away all four valence electrons, and acts as a hard acid like a typical highly-charged cation; this is mitigated by (2) it is a large cation, leading to high coordination numbers and varied geometry (e.g. 11-coordinated nitrate, 10-coordinated oxalate, 14-coordinated borohydride).
I could go a little further: for example, (1) happens for Th but not Ce because 5f is relativistically destabilised more than 4f. But these two are the main things that I would say would count as a brief introduction to Th's personality. (I would still note that Th, U, and Pu are quite approachable, unlike the other actinides with their murderous self-destructive urges, which accounts for the differing knowledge of their chemistry.) There are a few chemical trends across the actinides (e.g. increasing reactivity) but since Th is the first of them, it's not so relevant: in any case Th is already reactive enough to tarnish in air, so the only difference with the later ones is how quickly this happens. (Ac does not conform to that trend at all.) Double sharp (talk) 16:09, 21 July 2016 (UTC)[reply]
I would split the overview for the main Th article into inorganic and organomteallic compounds after this intro. Then I would simply write that the binary compounds can mostly be prepared just by direct reaction from Th and the nonmetal you want upon heating. The most useful are with B, C, N, and Si, which are chemically stable and refractory and hence are good choices for nuclear fuels. Then thoria needs a whole paragraph to itself. Halides can all be lumped in one paragraph, with a brief note regarding how ThF4 is different from the other three, and the fact that the lower iodides are electrides.
I don't think we need to mention the usual spectroscopic stuff because Th4+ is basically always colourless – though I'll keep it in mind for Ce4+ in the Ce article, where I need to explain why it is orange (metal→ligand charge transfer). The hydroxide and its decomposition can be mentioned when covering (1) in the opening paragraph. (Do we need to mention the false Th3+? Or just make it a note?)
Finally organometallic notes that this is focused on cyclopentadienyls and cyclooctatetraenyls (mention thorocene, it's the easiest to explain), and say that 5f involvement means significant covalent character (hence this is the only chance to get to the +3 and +2 states stably). Apart from this, the chemistry is poorly known (no known structure for tetrabenzylthorium, unsubstituted tetramethylthorium not even known). How does this proposed shortened version sound? Double sharp (talk) 16:26, 21 July 2016 (UTC)[reply]
I see what I would want to do, but let's get to it after we're done with Occurrence, okay?--R8R (talk) 17:30, 21 July 2016 (UTC)[reply]

I wanted to start off with something like "I'm copying anything we have to a new subarticle, compounds of thorium, and now we can think fresh." But you already did that :) great

My idea to write the section on chemistry generally focuses on subsections, ordered approximately as follows: electronic config and properties of a singular atom--reactivity--oxidation state 1--2--3--organometallic chemistry. I think we need to move from regular section where we have subsections for the oxide, halides, etc.: this is available in more appropriate corresponding articles and we're talking about the element, so we need to focus on the element and its behavior (electrons, reactivity, ions). I think Lead#Chemical characteristics is good at this, keeping the size of the section not too inflated. Okay, the dioxide is a big deal and we can describe it in short, but not every halide, carbide, nitrite, etc. I see you say thorium has a great chemistry of complexes: if so, adding a short subsection on this (1--2 paras) may be a good idea. I'd mention radiolysis before any subheaders and put nothing else there. Should look interesting to read. Also, try to add these subheaders.--R8R (talk) 20:31, 22 July 2016 (UTC)[reply]

How is it now? Double sharp (talk) 15:06, 23 July 2016 (UTC)[reply]
I gave it a very brief look. Much, much better, though I see potential for improvement and detailed reading is yet to follow. More on this in two or three hours.--R8R (talk) 16:32, 23 July 2016 (UTC)[reply]
  • "Four atomic orbitals are theoretically available for the valence electrons to occupy: 5f, 6d, 7s, and 7p. However, the 7p orbital is greatly destabilised and hence it is not occupied in the ground state of any thorium ion." how come you say 7p is "theoretically available for the valence electrons to occupy" when it "is greatly destabilised and hence it is not occupied in the ground state of any thorium ion"? seems logically inconsistent. why isn't, say, 8s theoretically available?
    • Wickleder et al. say it this way, but I agree it looks silly. The main point is that 5f, 6d, and 7s are close in energy, while 7p is a lot higher, but this is not really unexpected. Removed 7p. Double sharp (talk) 04:28, 24 July 2016 (UTC)[reply]
  • "Despite thorium's position in the f-block of the periodic table, it has an anomalous [Rn]6d27s2 electron configuration in the ground state, as the 5f and 6d subshells in the early actinides are very close in energy, even more so than the 4f and 5d subshells of the lanthanides: in fact, thorium's 6d subshells are lower in energy than its 5f subshells, because its 5f subshells are not well-shielded by the filled 6s and 6p subshells and are destabilised. The closeness in energy levels of the 5f, 6d, and 7s energy levels of thorium result in thorium almost always losing all four of its valence electrons and hence occurring in its highest possible oxidation state of +4." nice talk (really nice), but I thibk adding a word on the SO interaction helps a bit to a reader not familiar with this. (What's been said in lead, for example, is enough.)
  • "This behaviour much more similar to the transition metals zirconium and hafnium than to that of the lanthanide cerium..." I think four words are missing here: "therefore" (because the previous talk explains the reason for this), "is" (English grammar ;), and "those of" (reads better)
  • "Although nuclear instability is a major problem for most of the radioactive elements, resulting in their compounds being hazardous to handle and study and being only available in small quantities and being highly prone to radiolysis, the build-up of daughters and heat generation that alter observed properties, thorium, uranium, and technetium are so stable that these problems do not apply to their compounds." sooooo... it's not a big deal here, so why even mention it?
    • Well, it goes back to what you said on your talk page about Th and U being almost normal elements. (Even Tc hasn't been investigated quite as well, probably because you need to make it artificially, while you can just mine Th and U out of the ground.) So I edited it down to "Thorium and uranium are the most investigated of the radioactive elements because their radioactivity is slight enough to not pose major problems of handling and accessibility." Double sharp (talk) 04:28, 24 July 2016 (UTC)[reply]
  • "Thorium is a highly reactive and electropositive metal. At standard temperature and pressure, it is slowly attacked by water..." the first thing I imagine when I hear "reactive metal" is its oxidation by the air... let's start with that. the section is fine otherwise.
  • "When heated, it emits intense blue light" why?
  • In general, Inorganic compounds is okay. As of now, it'll probably pass an FAC.
  • "The heavier pnictogens also form binary thorium compounds." first, I suggest not using terms "chalcogens", "pnictogens", etc. when possible ("halogen" is a well-known term by anyone, in contrast to these). Also, what do we get? Is there (say) Th3Bi4?
    • Yup! There is Th3Bi4! (And also the analogous N, P, As, and Sb compounds.) There are also binary compounds with Si and Ge. The contents of Gmelin are a good way to see at a glance how much is known for each element. (Notice how thorium and uranium drown out all the other radioactive elements. Even technetium is simply not in the running.)
    • The reason I have these little throwaway sentences, that are expounded more on in compounds of thorium, is that I mentioned back at the beginning of this section that you could get thorium compounds with most nonmetals by just heating the elements together, and I felt a little bound to say which elements you could do that with. So now you will notice that I cover the hydrides, oxides, and halides in detail, and just quickly mention in these throwaway sentences what other elements you can get (B; C, Si, Ge; N, P, As, Sb, Bi; O, S, Se, Te). I at least linked chalcogen and pnictogen and defined which elements we are talking about here in parentheses (excluding Po), so it's not so bad. Double sharp (talk) 03:58, 24 July 2016 (UTC)[reply]
  • "Thorium is the only element that forms a hydride higher than MH3" what about stannane and plumbane, not to mention methane?
    • You're right. I suppose Morss (the source) was only thinking about the left end of the table and completely forgot about the right end. CH4 isn't a hydride (carbon is a little more electronegative), but your point stands perfectly about SnH4 and PbH4. Double sharp (talk) 03:58, 24 July 2016 (UTC)[reply]
  • "In aqueous solution, thorium occurs exclusively as the tetrapositive aqua ion [Th(H2O)9]4+, which has tricapped trigonal prismatic molecular geometry:[47][48] at pH < 3, the solutions of thorium salts are dominated by this cation." as is, this is very inconsistent. So Th exists in solutions solely as [Th(H2O)9]4+, and then solution of Th salts are dominated by this ion only "at pH < 3"? what happens under other pH values? this -- "predominantly to [Th2(OH)2]6+ in solutions with pH 3 or below" -- is further confusing.
    • I redid this properly; it was confused. AFAIK, when pH is below 3, you get practically all [Th(H2O)9]4+, but as you raise the pH beyond that, the hydrolysis starts to happen and can go all the way to the hydroxide. Double sharp (talk) 04:28, 24 July 2016 (UTC)[reply]
  • At this point, I must say I underestimated the section at first. Not only it's undergone a great improvement, you've written a very solid section. This is very interesting to read and seems pretty characterizing to me.

I gave it a deep breath to think if anything's missing and I still like it.--R8R (talk) 19:05, 23 July 2016 (UTC)[reply]

Production
[edit]

One major aspect this section is neglecting is: who makes thorium? we get to learn how thorium is made, but not by whom exactly. I want to know the companies (if available; I got the names of the 11 companies making fluorine gas in Ullmann, for example, but what if only, say, three companies produce thorium?), countries, tonnage, etc.

There is not that much demand for Th, so companies do not make it as the main product: this must be why I didn't find any listings. The meagre quantities we do have are made as by-products of the production of Ln and U. Added some extra information regarding countries and tonnage. Double sharp (talk) 07:28, 29 July 2016 (UTC)[reply]
It would still be cool to add such a basic description in the beginning of the section. I see you have the info, I just think it'd be better to move it up the text. by the way, here are comments re that para:
  • " Half of this thorium produced is used in gas mantles." belongs to a different section
  • "Nevertheless, production could easily be increased, and probably would be" second conditional? so there are few chances of that?
  • "Present knowledge of the distribution of thorium resources is poor because of the relatively low-key exploration efforts arising out of insignificant demand. India is believed to possess the largest supply of thorium in the world, making up almost half of world reserves, but not even a thousandth of these reserves have been extracted.[98]" belongs to another section--R8R (talk) 21:49, 31 July 2016 (UTC)[reply]

Not ready for an actual review today, sorry. But one question bothers me: please explain here the oxidation states in "thorium diphosphate (Th(PO4)2)"

This was copied from actinide, but I think there is a misunderstanding here that I didn't notice in 2014 when I copied it over. Diphosphate does not mean two PO3−
4 anions; it refers to the pyrophosphate anion P
2O4−
7. Indeed ThP2O7 is known to exist, unlike the supposed compound with the formula stated. Changed. Double sharp (talk) 07:18, 29 July 2016 (UTC)[reply]

--R8R (talk) 21:04, 26 July 2016 (UTC)[reply]

  • "Thorium is extracted mostly from monazite: thorium pyrophosphate (ThP2O7) is reacted with nitric acid, and the produced thorium nitrate treated with tributyl phosphate. Rare-earth impurities are separated by increasing the pH in sulfate solution.[95]
In another extraction method" now wait a second. I didn't even realize the first para was an extraction method on my first read until I saw you suddenly jumped to another one. So, the flow here is weak. You would be better off starting with a para says that thorium is a rare metal (or something) and there is no (or few) minerals that have Th as its primary component (I understand there are such minerals, but they are exceptionally rare; am I correct?). You've mentioned that before and you may refer to this as to a fact you'd introduced a reader to. "Since there are no/whatever minerals that have Th as its principal component, Th is mined from minerals in which it is found as an impurity. Most production relies on monazite, which is worldwide abundant and often contains some Th [you already said that, so half a sentence is enough]. Other minerals are sometimes used, but this is rare. [is that correct? right now you're saying most production relies on monazite]"
And then go with a para that describes the first production method.

I found the original USGS report and will change some things. (Most production relies on monazite because it is mined for the rare earth content and Th is produced as a by-product. If demand for Th ever increased, we would probably be relying on thorite instead.) Double sharp (talk) 06:50, 2 August 2016 (UTC)[reply]

I'll wait for the change to come and skip the section for now.--R8R (talk) 11:15, 2 August 2016 (UTC)[reply]


Uses
[edit]
  • "Many applications of thorium are becoming obsolete due to environmental concerns largely stemming from the radioactivity of thorium and its decay products;[29] though these were known for a long time, the phasing out of thorium was greatly delayed because no serviceable substitutes were known until the 1990s.[96]" right, except we already mentioned that in History. This section is called Applications, so focus on what's important here: the fact that thorium is being phased out. You're describing the present here, no need to refer to the nineties or anything.
  • "One notable exception is the use of thoria..." this caught me. Why is it "thoria" and not the systematic "thorium dioxide"? If the former is actually more commonly used among those who use it, you should explicitly say that on first mention (which now is "In air, thorium burns to form the simple dioxide, ThO2, also called thoria or thorina." See, you clearly refer to ThO2 as "thorium dioxide" which is also called "thoria", and then it suddenly becomes the main name) or here.
  • "The electrodes labelled EWTH-1 contain 1% thoria, while those labelled EWTH-2 contain 2%.[102]" too detaile here
  • Also, how does it work and shouldn't it be introduced after you say ThO2 is so refractory?
  • "Only a few elements (including tungsten and carbon) and a few compounds (including tantalum carbide) have higher melting points.[40]" why mention tantalum carbide, all of a sudden? actually, same question regarding W and C
  • "This means that when heated to high temperatures, it does not melt, but merely glows with an intense blue light" why? surely I thought I knew why (though a quick explanation in a note would not hurt, as many people are not aware of colors of hot beyond red, yellow, and white), but how does addition of cerium dioxide change that?
  • "This property of thoria means that thoria and thorium nitrate" a property of thoria means nothing for thorium nitrate
    • Actually it does, because at such high temperatures Th(NO3)4 will thermally decompose to ThO2, NO2, and O2. So sometimes Th(NO3)4 is used instead, since it will generate thoria on heating. Double sharp (talk) 12:38, 17 August 2016 (UTC)[reply]
  • "This property of thoria means that thoria and thorium nitrate are used in mantles of portable gas lights..." even the last thing aside, this is still incorrectly worded. "This property has been exploited/become the basis/anything in its use in mantles of portable gas lights and something"
  • "200 mrem (2 mSv)" I've been explained what "mrem" is, but what is "mSv"? At least link to sievert (unit) or something. Also, rem and sievert are different units and measure different things. The equivalent to sievert would be roentgen. (Don't know what would be the best thing to do; just be sure whatever you will is the best)
  • "A study in 1981 estimated that the dose from using a thorium mantle every weekend..." come to think of that, that would fit just nicely into the para in History where we discuss the phaseout
It wasn't as bad as I thought, just one misplaced para ruined the flow.--R8R (talk) 14:38, 6 August 2016 (UTC)[reply]
  • "One use of thoria is not being phased out from is in gas tungsten arc welding (GTAW) to increase the high-temperature strength of tungsten electrodes and improve arc stability." question 1: why not? question 2: how does it work? question 3: does this require a high Th percentage?
  • "In electronic equipment, thorium coating of tungsten wire improves the electron emission of heated cathodes.[35]" question 1" is it related to the previous use? questions 2 and 3: same
  • "heat-resistant ceramics" good para, but I have two issues with it. first, does "high-quality lenses for cameras" refer to regular consumer-available cameras or some sort of professional ones? second, does the whole yellowing part belong in this overview article?
  • You can't mix uses with former uses. Establish a separate subsection or, which I find better, move the most important info to the history section which is weak on historical uses anyway and delete the rest.
  • "filaments" my first reaction to that word was to find out what it even meant, so a wlink would be appropriate
  • "Thoria was used to control the grain size of tungsten metal used for spirals of electric lamps. Thoriated tungsten elements are found in the filaments of vacuum tubes, e.g. magnetron found in microwave oven." as is, these two sentences don't belong together. Tense suddenly changes from past to present. second, they don't seem related, though it seems a following sentence tries to establish a relation. If this para actually mentions related issues, then probably start off with that relating thing and then explain use by use how it is relevant.
  • "its radiation is primarily due to alpha particles" also could be moved to the beginning of the section, as it's true for thorium's radiation in general
  • At this point, I finally realized one thing that should've become clear to me long ago is not clear yet and as obvious as it sounds now that I did understand it, I never thought in detail before and it wasn't as clear (and your text should be clear from the beginning). Thorium gas mantle is a portable source of light that requires no electricity. Aha! This simple fact changed everything. But why is thorium so good for this use? (I don't know yet.)--R8R (talk) 15:31, 6 August 2016 (UTC)[reply]

I've added many comments with questions throughout the section. I've been concerned with making this look readable and couldn't yet look for answers. Please do--R8R (talk) 16:16, 6 August 2016 (UTC)[reply]

Nuclear energy
[edit]

Is it a real application when it is only a possible use? For me all the nuclear applications belong at the end of the section. There are real but slowly phasing out applications. The nuclear applications are planned for the futur or they are research applications long closed down. The thorium fuel cycle is no more real than the breader reactors of the uranium fuel cycle. The radio isotop dating in the uranium article is part of the isotopes section and there it fits much better than in the application section. --Stone (talk) 19:03, 31 July 2016 (UTC)[reply]

It is not just a possible use; there really is one active reactor today in India using Th as well as U. Anyway, if Greenwood and Earnshaw (as well as the Wickleder review) put it under their own sections for applications (radiometric dating is also put there in Wickleder), it's good enough for me. (Seriously, Wickleder et al. call it "the largest potential for thorium", and this in a review of thorium chemistry instead of a glowing pro-thorium-power pamphlet.) I think it makes more sense to put in applications that may be on the rise first, before those that are on the wane. Today, thorium tends to be used only when its radioactivity is needed. Double sharp (talk) 08:24, 1 August 2016 (UTC)[reply]
I can not look into the future and I doubt that Greenwood and Wickleder can do. Thorium-based_nuclear_power#Current_projects#India clearly states that it is not running. This is a Prototype which makes it a lab test equipmemnt but not a seriuos use. I can not see any serious efford to make this a large scale use. __Stone (talk) 20:57, 1 August 2016 (UTC)[reply]
Under "Nuclear reactors and atomic energy" (under applications) Greenwood starts by covering 235U and its long history, and then mentions 233U and 239Pu under the same section, writing about the advantages of 233U and then mentioning the reprocessing problems because of the energetic gamma decay of the daughters. (Yes, he also writes a whole paragraph about the prototype breeder reactors for 239Pu, also as an application.) Further, Wickleder is very positive about the whole thing, listing it after the non-nuclear applications: "Maybe the largest potential for thorium is its use in nuclear energy." And after listing advantages and disadvantages he writes "The nuclear technology has nevertheless matured with the development of high-temperature gas-cooled reactors". Also, the Indian official programme looks like a very serious, governmental effort to make Th reactors happen (along with the reactor at Kalpakkam, which uses some 233U as well as 235U and 239Pu). Double sharp (talk) 06:57, 2 August 2016 (UTC)[reply]
The Chinese will start the reactor in the 2030s and the Indians have not yet selected a building site according to the USGS comodity report. To make the future for thorium what it is proposed by the crystall ball fraction a lot of things have to happen in the future. Best would be a section on nuclear fuel, but with much less enthusiasm and kill it completely from the use section, because it is not a use it is a future use. --Stone (talk) 20:51, 3 August 2016 (UTC)[reply]
The new organization in the text is really looking great!--Stone (talk) 20:47, 17 August 2016 (UTC)[reply]
  • "The main advantage of the thorium fuel cycle is that thorium is more abundant than uranium and hence can satisfy world energy demands for longer." (warning: I'm poorly familiar with the nuclear technology) you surely don't mean people are going to mine all uranium or thorium so relative abundance becomes relevant? I'd think what is more relevant is easiness of extraction of the elements from mines and mining itself
  • "not only does 233U have a higher probability of fission upon neutron capture than 235U" for the record, what quantities are we talking about? Probably suitable for a note
  • "(n,2n) reactions" I understand it, but this is somewhat hardcore. Maybe if you rewrite the reaction chain in this notation, it becomes easier to get on with (the chain would also be technically more accurate). By the way, do you actually need that chain?
  • you mention the advantages, then you mention the disadvantages, and then it suddenly turns out there are more advantages and disadvantages! Restructure this.
  • Also, commercial viability deserves its own discussion, it's not just another disadvantage. Why is it not viable, by the way?
  • "In 1997, the U.S. Energy Department underwrote research into thorium fuel" this whole discussion belongs to History
  • "other companies: Raytheon Nuclear Inc., Brookhaven National Laboratory and the Kurchatov Institute in Moscow." Why is location given only for one institute? Why are they all referred to as companies?
  • The story is a little weak here if you look closely: the U.S. considered an idea and an Isreali scientist formed a coalition. Tgis could be the case, but this deserves an explanation
  • "USA's" it is advised not to use the three-letter acronym in Wiki for whatever reason per MOS
  • "with the goal of achieving energy independence" who is India dependent on with energy? Really interested
  • Stone said the Chinese will launch their first site in the 2030s. Would be nice to mention that here. Who has any plans aside from China and India?

The section is more or less good on the technical part.--R8R (talk) 19:39, 8 August 2016 (UTC)[reply]

  • But there's an issue I forgot to mention. That wikitexted graph. First of all, it has increase of Z doing down rather than the usual up, but that's the least of my concerns (though please change that too). What do the colors mean? I know what the fact there is a color means, but what do different colors mean? Wouldn't it be better to ask the Graphics Lab to make a svg graph with a legend and beauty and stuff?--R8R (talk) 19:56, 8 August 2016 (UTC)[reply]
    • Different colours refer to different orders of magnitude of half-lives, but I am not entirely sure if it matters enough that it should be mentioned. I think part of the motivation for Z increasing going down is to show the fission of 232U, 233U, and 235U, but actually I think what I would do is to touch up a chart of nuclides with arrows and give the three fissile uranium nuclides there a red border or something. Double sharp (talk) 12:15, 17 August 2016 (UTC)[reply]
Precautions
[edit]
  • "As thorium occurs naturally, it exists in very small quantities almost everywhere on Earth: the average human contains about 100 micrograms of thorium and typically consumes three micrograms per day of thorium.[130]" nice start! (no action required)
  • "This exposure is raised for people who ..." nice continuation! (again, no action required)
  • "exposure to an aerosol of thorium" how could that happen?
  • "As a result, owning and handling small amounts of thorium, such as a gas mantle, is considered safe. [...] There are concerns about the safety of thorium mantles" uhmm?
    • I think the idea is that everyone agrees that a thorium gas mantle is perfectly safe as long as you don't use it. The source says "gas lantern mantles...generally do not pose serious health risks, but may nevertheless be retired from use as a prudent avoidance measure." The problem is that it is perfectly safe as long as it sits there because the thorium and its daughters can't get into you, but upon use everything is volatilised and suddenly they can. Clarified. Double sharp (talk) 16:42, 3 September 2016 (UTC)[reply]
  • "If a mantle is ingested" how could that happen? like really, how?--R8R (talk) 20:10, 8 August 2016 (UTC)[reply]
    • This was in the source. I could imagine young children trying it. The source cited explicitly notes this. Alas, I have found that it is a rather futile quest to drink to the dregs the bottomless cups of human stupidity. Double sharp (talk) 16:42, 3 September 2016 (UTC)[reply]
  • Is anything known on how thorium's chemistry harms the body?
    • I tried researching on this, but found nothing. If it's anywhere, it must be in Gmelin somewhere. Presumably the reason is that the radioactivity drowns it out, unlike for uranium when you really have to take both chemical and radiological toxicity into account. In fact, the one study I found about this compared thorium with uranium and neptunium (because 238U and 237Np are the most common isotopes and are long-lived enough to not cause problems; 244Pu and 247Cm can't be produced in enough quantities). It showed that thorium was actually chemically rather non-toxic to cells, whereas uranium and neptunium induced apoptosis. It might have psychological effects, judging from [www.omicsonline.org/occupational-thorium-exposure-or-self-poisoning-2161-0494.S5-002.php?aid=5345[predatory publisher] this study], but this patient's paranoia may have predated his minuscule thorium exposure. Double sharp (talk) 16:42, 3 September 2016 (UTC)[reply]
  • "The burning of thorium metal powder sludge resulted in the 1956 Sylvania Electric Products explosion, which resulted in nine injuries, some severe, as well as one death from thorium poisoning.[139][140][141]" the sentence is poorly worded: it puts the stress on the explosion and not on those injured and dead.--R8R (talk) 20:10, 8 August 2016 (UTC)[reply]
Notes
[edit]

I succeeded in cutting the notes down from the ridiculous 26 there used to be to 10. ^_^ Double sharp (talk) 13:29, 23 July 2016 (UTC)[reply]

Ten is a very decent number. Looks like many (and the article looks well-researched) but not too many (and the impression isn't ruined). I think I'd put ten or twelve as the upper limit.--R8R (talk) 16:25, 23 July 2016 (UTC)[reply]
Lead section
[edit]

My general advice is: use four paras, first introductory and mentioning physics and/or chem, second on history, third on application and fourth on biology/ecology. See fluorine for an example. Maybe another para on isotopes would be appropriate here (though I'd try to avoid that, there is really one isotope that matters). History is currently ridiculously small here, not to mention any properties.--R8R (talk) 20:17, 8 August 2016 (UTC)[reply]

Pictures
[edit]
  • Can we get a picture of a big chunk of Th for Bulkproperties, even if in poor quality?
    • We used to have one, but it got deleted as it wasn't a free picture. It is actually annoyingly difficult to get large chunks of thorium metal. This is because the usual amounts of lead shielding that work perfectly fine for uranium metal are insufficient, because the particles emitted by the decaying daughters of thorium are too high in energy. Double sharp (talk) 05:18, 10 August 2016 (UTC)[reply]
  • any pic of that Th aqueous ion would be better than the uncalled for pic of ThO2 with oxygen being fluorine-colored. Are any photos of actual compounds available?
  • can we get a pic of a burning mantle?
  • a thorium production plant?
  • a thorium-based reactor (a model will work)

--R8R (talk) 20:57, 8 August 2016 (UTC)[reply]

I re-read fluorine; indeed, it is a masterpiece and it wouldn't have been one without TCO. What I want to say now is, can we get as many pictures? They also make the text they surround more interesting, so this is important (which is why I even gave it its own subheader in this review).--R8R (talk) 17:11, 9 August 2016 (UTC)[reply]
To do
[edit]

This list is supported to contain the issues temporarily skipped. Still, I don't want to overlook these.--R8R (talk) 20:17, 21 July 2016 (UTC)[reply]

  • Why was Th phased out only in the nineties?
    • I finally found the reason: because it was only then that adequate substitutes were found. Previously thorium was thought to be indispensable, for example for getting the really bright light from the mantles, until it was noticed that yttrium was almost as good for this purpose, and similarly alternatives were found for the other applications. (Th is still usually the best, but the competitors are now known to be close enough that the benefits of Th are outweighed by the dangers of radioactivity – mostly not from Th, but its murderous daughters.) Double sharp (talk) 15:05, 23 July 2016 (UTC)[reply]
      • Wow. Thank you for finding this out. One last question: was thorium used before substitutes were found labeled as/considered to any extent dangerous in the practical sense? For example, americium in smoke detecors isn't considered dangerous because there's so little of it there IIRC.
        • Yes, in practice there are some dangers. I'll use the old thorium mantles as the main example here, since it was always among the largest uses and has the most problems (which are still made and sold by some companies, who tend to avoid mentioning radioactivity whenever possible, which is somewhat dubious from a safety or legal point of view). There is the radiation dose you get every time you use it, because while the Th is fine, the Ra is volatilised and you can easily breathe it in. Apart from that, the main danger is not to users (provided they use it properly), but rather to the factory workers and the environmental damage they cause in landfills, because while the radiation from one mantle is not so bad, that from the large number of mantles gathered together at the factory or the landfill is quite a big problem. This (which I added) was certainly known by the 1980s, as that's when the sources I added came from. In the case of thorium as a contrast medium, the dangers were already known by the 1950s, and the switch was faster because there was an alternative. (It was used a lot in the 1930s and 1940s because there was no good alternative yet.) Double sharp (talk) 16:43, 23 July 2016 (UTC)[reply]
          • Thank you. I'll look in a few hours how I would want to accommodate this into the text, but in general, such facts and research are FA-worthy, very interesting to learn.--R8R (talk) 16:55, 23 July 2016 (UTC)[reply]
  • History of nuclear weapons and reactors?
  • Rethink Bulk properties in general
  • Find a reason why 230Th occurs in seawaters
    • It's always around (see the infobox which lists the isotopic composition as 99.98% 232Th and 0.02% 230Th); it's just easier to detect in seawaters, because while 232Th would sit at the bottom, you get to see 230Th precipitate out and sink down as it is the daughter of soluble 234U. Actually, wasn't this already in Isotopes? Double sharp (talk) 11:56, 22 July 2016 (UTC)[reply]
  • Add a para with stats to Formation (see, for example, last para in Lead#In space)

Why is thorium so stable? I admit, I did try to answer this question. After Pb completes a proton shell at Z=82, the next subshell to be filled is according to this site 1h9/2, which gets us to Z=92. Which explains uranium nicely, but not thorium. Perversely, if you look at the neutron subshells after N=126, 2g9/2 gets us to N=136 and then 3d5/2 to N=142, which explains thorium nicely, but not uranium. Then again, since actinide nuclei are not spherical, we should not expect these predictions to be sensible in the first place. This may not actually be explainable in an understandable manner for the actinides. (I dare to say this sort of thing for the spherical early lanthanide nuclei; see the discussion I wrote for cerium, for which this is actually a reason why it is so common. But for nuclei with 150 < A < 190 and A > 220, the shell model simply does not apply, even in the vicinity of the line of beta stability, because these nuclei are not spherical.) Double sharp (talk) 10:30, 26 July 2016 (UTC)[reply]

  • Get back to Production after it's basically reformed
  • Write to that Dutch company that employed the two guys from 1914 whose names we cannot find
  • Thorium energy in the 21st century?
  • Why do we need more than a sentence for radiodating? It's easy to explain, but is that needed?

N

[edit]

Continued at Talk:Thorium/PR continued with R8R. Double sharp (talk) 01:30, 12 May 2017 (UTC)[reply]

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