Talk:Astatine

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Good article Astatine has been listed as one of the Natural sciences good articles under the good article criteria. If you can improve it further, please do so. If it no longer meets these criteria, you can reassess it.
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A-class review[edit]

Astatine

The time has come, and this is the first A-class review for our WikiProject. I believe the article suits A1-A4 well, and I don't know what could be done to suit A5. I wish to push it to FAC later, and first undergo this. This article, in some places, is done like the FAC of francium. Any suggestions and opinions are surely welcome.--R8R Gtrs (talk) 09:35, 20 September 2011 (UTC)

Seems good. I don't know what could be done to get a picture; I tried and found nothing. Yankeesrule3 (talk) 01:53, 26 September 2011 (UTC)
Closed as it's long-lasting with no consensus on it--R8R Gtrs (talk) 17:18, 30 October 2011 (UTC)

GA Review[edit]

This review is transcluded from Talk:Astatine/GA1. The edit link for this section can be used to add comments to the review.

Reviewer: Yankeesrule3 (talk · contribs) 15:33, 31 October 2011 (UTC)

I will be reviewing this article, and it is the first article I will be reviewing as an official member of WP:ELEM.

GA review – see WP:WIAGA for criteria


  1. Is it reasonably well written?
    A. Prose quality:
    B. MoS compliance for lead, layout, words to watch, fiction, and lists:
  2. Is it factually accurate and verifiable?
    A. References to sources:
    B. Citation of reliable sources where necessary:
    C. No original research:
  3. Is it broad in its coverage?
    A. Major aspects:
    B. Focused:
  4. Is it neutral?
    Fair representation without bias:
  5. Is it stable?
    No edit wars, etc:
  6. Does it contain images to illustrate the topic?
    A. Images are copyright tagged, and non-free images have fair use rationales:
    No images, so not applicable to this GA review
    B. Images are provided where possible and appropriate, with suitable captions:
    Images of astatine, unfortunately, are virtually nonexistant, and I doubt we will ever get an image for this element. I will let this slide, but if an image ever becomes available, it needs to be inserted into this article ASAP.
  7. Overall:
    Pass or Fail:

Characteristics[edit]

  • 1st para, second sentence: Source for number?
    My OR based on simple laws. I don't insist on the inclusion, removed.--R8R Gtrs (talk) 12:23, 1 November 2011 (UTC)
  • 2nd para, first sentence: When you say "it," what are you referring to?
    I thought that that sentence was quite clear; removed, however, in order not to confuse anyone.--R8R Gtrs (talk) 12:23, 1 November 2011 (UTC)
  • 3rd para, first sentence: Restates info in 2nd para, last sentence.
    It doesn't actually. The last sentence of the second para says nothing about that it's a solid.--R8R Gtrs (talk) 12:23, 1 November 2011 (UTC)

Other than these three points, seems good

History[edit]

  • 3rd para, last sentence: Three out of four what?
    Fixed.--R8R Gtrs (talk) 12:23, 1 November 2011 (UTC)

Other than this one point, seems good

Natural Occurrence[edit]

  • 1st para, second sentence: "This rarity is explained with that..." is a very awkward phrase.
    Fixed--R8R Gtrs (talk) 12:23, 1 November 2011 (UTC)
  • 2nd para, last sentence: "...Has a daughter of..." is strange wording.
    Fixed--R8R Gtrs (talk) 12:23, 1 November 2011 (UTC)

Other than these, seems good


Many printed and online sources say that the total amount of astatine in the Earth's crust is "probably less than one ounce" or "about one ounce" or the equivalent in metric units ("about 25 grams"). However, no derivation is shown by these sources. Perhaps the originator of this estimate applied the crustal abundance calculation to the whole mass of the Earth, including the core and mantle, which would yield a total of 24 grams in the entire Earth. However, that would still be a questionable figure because the abundance of ancestor isotopes in the whole mass of the Earth is probably quite different from that of the crust.

The book Holleman-Wiberg's Inorganic Chemistry correctly gives a figure of "3·10-24 % by weight" (3 x 10-26) as the crustal abundance and "no more than 45 milligrams" (0.045 gram) as the total amount of astatine in the Earth's crust. A detailed calculation is available at http://ataridogdaze.com/science/As-Earth-crust.html

Gwc100 (talk) 16:50, 22 August 2013 (UTC)

Chemical reactivity and compounds[edit]

  • 2nd para, second sentence: Sentence seems overly long, could be split into multiple sentences.
    OK, done.--R8R Gtrs (talk) 07:23, 2 November 2011 (UTC)
  • 3rd para, second-to-last sentence: Seems overly short, and has non-encyclopedic wording.
    I'm afraid, astatine is not iodine, there's not that much info. Some things known for stable elements compounds are principally unknown for astatine. And I guess if there's more info on the compounds' properties, it'll be very technical and uninteresting (bond lengths, molecular structures, so on. To be honest, I have searched and haven't seen such info yet). This is not a phenomenon: the FA of francium has no Compounds section at all (not because it an alkali metal; its upper neighbor caesium has one). Non-encyclopedic writing is a problem I will not deny, but to be honest, I don't see it. What's exactly wrong? What could I do?
    I have reworded the part "has seen the light". This was what I was talking about. Sorry if I wasn't clear on this, I should have specified the exact words. Yankeesrule3 (talk) 19:08, 2 November 2011 (UTC)

Other than these two points, all is good

Production and uses[edit]

This whole section seems good for a GA. It probably would not be OK for a FA, but for a GA it is fine.

Isotopes[edit]

Nothing wrong here, probably could get past even a FA review.

Lead[edit]

All statements backed up at some point in main body.


As soon as the chemical reactivity and compounds section is fixed, this should pass the GA review! Yankeesrule3 (talk) 22:38, 1 November 2011 (UTC)

I am now ready to pass this GA review for Astatine. Great job on the article! Yankeesrule3 (talk) 19:12, 2 November 2011 (UTC)

Naming of isotopes[edit]

I'm currently giving copyediting the page a try. Would it be preferable to use (for instance) 211Astatine (or 211At) or Astatine-211, for consistency? I'm not finding anything on this at, for instance, WikiProject Elements. The Isotopes of astatine page uses superscripts, while the FA Californium usually doesn't but sometimes puts that form in parentheses. Thanks! Allens (talk) 01:18, 18 February 2012 (UTC)

Hmmm, good question. I actually tend to name them like "astatine-211," but it's too problematic sometimes. Maybe we could switch to all symbols, 211At. I think, it's the best.--R8R Gtrs (talk) 16:49, 19 February 2012 (UTC)
OK, will do. Allens (talk) 18:22, 19 February 2012 (UTC)

Just re-read the article. Noticed that astatine isotopes are written as symbols, but other elements' are written in full. Is it OK? If you say yes, then yes. Maybe (and I'm becoming inclined to it) we could use symbols only in Isotopes section , as we do with chemical formulas in Chemistry section (solvents, etc. are written in full). What do you think? R8R Gtrs (talk) 21:08, 3 March 2012 (UTC)

Good question; should have seen that earlier myself. Hmm... I'm actually thinking 209Bismuth (as an example). That way, the reader doesn't need to know any chemical symbols other than for astatine, but it's more consistent with the astatine symbols. Your thoughts? Allens (talk | contribs) 21:42, 3 March 2012 (UTC)
Rather no; this isn't a way it is used in the literature and I even think this isn't correct; "bismuth-209," on the other hand, is pretty fine and has the same functions. Adding it, however, may make the thing too hard to read (but also may not). This was why I asked; if you see the way fine, I'll keep it the same.--R8R Gtrs (talk) 13:21, 14 March 2012 (UTC)
I wouldn't say "bismuth-209" or similar is hard to read; it's a pretty fair rendering of how they're (at least sometimes) talked about. I suggest keeping it the same for now, with a possibility for future revision (I'm thinking you or I might ask at WikiProject Elements and see if there's any sort of consensus among those who can decide for one or the other; my personal taste should not dictate things...). Allens (talk | contribs) 14:11, 14 March 2012 (UTC)
I just meant I tried to follow the same suit originally, but then I got simply tired of "bismuth-209," "astatine-211," etc. Maybe there is a way to word it better and look fine (and, well, this is what the copy-editing is for!)--R8R Gtrs (talk) 14:40, 14 March 2012 (UTC)
The Francium FA uses francium-### except for when showing nuclear reactions or chemical compounds. That is actually a bit easier on the eyes to read, I now suspect - no "jumping up and down" as your eyes scan across the screen. About the only other "linear" way I can think of is something like astatine/211, but I can't see any advantage of that over astatine-211 (can you?), and the element-### method is in use in other articles. About the only thing I would alter about astatine-211 is to make it instead astatine–211, with an endash used instead of a hyphen (it's admittedly hard to tell the difference...) because the MOS says to use an endash wherever you could just as well use a /. Allens (talk | contribs) 21:47, 14 March 2012 (UTC)
I can't :) But I don't even think "astatine–211" will do (en-dash), Wiki has a rule on that as well. Also, I basically thought that a hyphen connects prats of a word, while dashes connect different words....don't they?--R8R Gtrs (talk) 13:50, 21 March 2012 (UTC)
Huh! Naming conventions are for the titles of articles, mainly, but yes, I can see using them as a guide - good find! And that's very easy to convert (search & replace). The rule of thumb you mentioned is a pretty good one, but like everything it has its exceptions - for instance, the MOS says that if you're adding a hyphen/dash for a prefix, and what you're adding it to has a space in it, you use a endash: pre–credit cards (as in, the time prior to the invention of credit cards). Will do the fixing shortly. Allens (talk | contribs) 20:22, 21 March 2012 (UTC)

Rearrange sections?[edit]

Should the sections be rearranged to match Wikipedia:WikiProject_Elements/Guidelines? Allens (talk) 01:27, 18 February 2012 (UTC)

Leaning towards no. That layout is useful for elements like calcium or tin-- elements that occur in nature, can be well-studied and made industrially. Check out francium (very close in context to astatine, of similar stability and in the same nuclear region (between Bi and Th)) or ununoctium, both FAs. Isotopes and occurrence are more (relatively for the element) important, and are separate sections; uses and precautions are less important, and are kept together, also giving impression of biological roles, another unimportant (at all here) topic.--R8R Gtrs (talk) 16:58, 19 February 2012 (UTC)
I'll take a look at those two (francium and ununoctium) and compare to the current section arrangement; good thought! Allens (talk) 18:23, 19 February 2012 (UTC)
I have rearranged the sections to be closer to the arrangement in francium and ununoctium, while still preserving a logical sequence (e.g., talking about isotopes before talking about medical uses of one particular isotope). Allens (talk | contribs) 21:41, 21 February 2012 (UTC)

Good order now, except for that I'd move Chemical reactivity below History. The most related is Isotopes, so would best do before it. (Can't go later as it's followed by its own "relatives.") What do you think?R8R Gtrs (talk) 18:10, 27 February 2012 (UTC)

I can see that as one possibility; the other possibility is to make "Chemical reactivity" a subsection of "General characteristics" (calling the latter something like "Characteristics" or "Properties"). What do you think? ;-} Allens (talk | contribs) 18:22, 27 February 2012 (UTC)

Don't wanna move it to make a subsection. Too big a section results. By the same logic, we need to move Isotopes there (an even bigger section). There's some charm in that it's small and of similar size with the others. Let it be so :) R8R Gtrs (talk) 18:38, 27 February 2012 (UTC)

No problem... and it is so. Allens (talk | contribs) 18:49, 27 February 2012 (UTC)
R8R Gtrs, Allens: Please reconsider. Astatine has a good story to tell, one that is essentially no different to any of the other elements. The content that has been posted to date is remarkable. I cannot see any reason to not follow the standard layout and to let the article take its place, on an equal footing, alongside the other elements. There is enough quality content to do so:
0 Lead section
1 Properties
1.1 Physical
1.2 Chemical
2 Isotopes
3 Occurrence
4 Synthesis
4.1 Formation
4.2 Separation
5 Reactivity and compounds
6 History
7 Uses and precautions
etc
Sandbh (talk) 05:33, 8 April 2012 (UTC)

I do see your point, but I'd keep it as it is. Astatine has a specific topic called "Synthesis." After it, I would normally prefer to see what I can do with this (i.e., uses). Because typically, the astatine synthesized goes where it can be used (not studied). Plus, even uses are still dependent on isotopes, thus there can't be far away. And why is History so far from the beginning?--R8R Gtrs (talk) 15:27, 8 April 2012 (UTC)

in an elements article I would normally like to see 1. Properties (physical, chemical, isotopes) then 2. Occurence; 3. Production; 4. Compounds; 5. Uses; 6. Precautions; and then 7. History. Uses generally comes after Compounds rather than Production, since elements and their compounds tend to be treated interchangeably in this context. Precautions comes after Uses to again provide context. History comes towards the end since most people want to know about the chemistry first and then the 'dry' stuff, although I tend to look at the history as the reward. History usually comes earlier when there is not enough chemistry to talk about, which is clearly not the case in this instance, I am pleased to note. Sandbh (talk) 11:37, 9 April 2012 (UTC)
What about francium's order? And why have reactivity/compounds so far from the chemical properties (among which reactivity is one)? Allens (talk | contribs) 12:36, 9 April 2012 (UTC)
IMHO, it's kinda distorted (do I have to write constructive criticism?). The latter note makes sense to me, am switching--R8R Gtrs (talk) 12:53, 9 April 2012 (UTC)
Re why reactivity/compounds is so far away from the chemical properties of the element. This is discussed in the explanation of the element template. Early sections are about the element (properties, occurrence, production) then its compounds. The order of the francium article IMO doesn't flow very well either. Sandbh (talk) 10:13, 10 April 2012 (UTC)

Trying to clarify[edit]

So:

  1. it is allocated{{clarify|reason=Plates out on a cathode?}}-- maybe. Honestly, I'm not a native speaker and exactly here don't feel the difference (ashamed to admit). The enormous paper Soviet dictionary I have doesn't tell what the diff is.
  • "Allocated" is typically understood as something that one would do with money or other resources - dividing the resource between items in a budget or whatever. I'm a bit confused as to why it'd be attracted to a cathode, though, considering that the previous sentence says it prefers being an anion (like other halogens). Allens (talk) 19:52, 19 February 2012 (UTC)
OK, thanks, I'll remember. To your confusion: the previous sentences describe the element as a nonmetal; this one is a contarst (highlighted enough, I think, but do whatever is the best)
  • OK, I've put in something. I concluded that (electro)plating should be primary, since it's there as a contrast to nonmetals, but that the possibility that sorption would be a better term should be noted along with Stone's reference (thanks!). Allens (talk | contribs) 19:22, 27 February 2012 (UTC)
  1. however, experiments have shown that the actual astatine electronegativity is slightly below that of hydrogen{{clarify|reason=So what would the electronegativity be then? Or does the Pauling scale not go that far?}}-- Around 2.2 but slightly below, maybe 2.18 or about that, but I never saw the exact number, books (even well-written and respected among the scientists) don't give a value.
  2. {{clarify|reason=Are the others not known, or simply not shown on the table?}}--simply not shown. No need in them all, just shows the extreme points: growth for alpha decay energy for At-211, the further growth for At-212 and -213, and decrease since then; also At-219, -220, and -221 to show alpha decay are not ~100% anymore.
  • It may be preferable to note these as "example" isotopes instead of just "several" isotopes. Allens (talk) 19:52, 19 February 2012 (UTC)
  1. {{clarify|reason=Why does the alpha decay probability jump around so much for lighter than astatine-210?}}-- Do you mean the exact jump for At-210--At-211 couple? If so, I dunno actually. Also seemed wicked for me (would normally expect the reverse). Will ask an expert (luckily, Wiki got some). If the whole At-210--At-213 row, then the peak for At-213 is easily explained: its daughter has 126 neutrons.
  • I was actually referring to the 207-210 group. The reason for the size of the jump for the 210-211 ones would also be nice, yes. Regarding the peak for At-213, in other words, it's because alpha decay produces an isotope (of something or another) that has an unusually stable number of neutrons? Allens (talk) 19:52, 19 February 2012 (UTC)
Gimme time. I'll find out (i.e. will check the book, or whatever). For At-213, yes. Once I have more time, I'll write a more profound explanation (yet keeping understandable), if you want. Not gonna be a problem.
could you for now remove the At213's daughter's stability note? As a reader, I am there wondering why is At211 (N=126) less stable than At210. And as a writer, I can't (yet) explain itR8R Gtrs (talk) 18:53, 27 February 2012 (UTC)
OK, it's commented out. Allens (talk | contribs) 19:09, 27 February 2012 (UTC)
May be helpful--R8R Gtrs (talk) 12:20, 22 March 2012 (UTC)
  1. The most stable of them is astatine-202m1,{{clarify|reason=The nuclear isomer article indicates that "m1" is not used, just "m", "m2", etc; a note may also be necessary to clarify exactly what astatine-202m1 means (first meta-state nuclear isomer of astatine-202)}}-- Half the truth, not always used, but sometimes is in scientific literature; the article itself names an isotope in that way. About explaining what "m1" means, you're probably right. I'll do it.
Have copyedited it - thanks! Allens (talk | contribs) 22:15, 3 March 2012 (UTC)
  1. attributed Minder's results to contamination of his radon stream (radon-222 is the parent isotope of polonium-218).{{clarify|reason=In other words, contamination of his radon stream with another radon isotope?}}-- hmmm... New isotopes, in order to be identified, are often not studied chemically, but their decays are instead. The radon was probably not just radon-222, but also with traces of some beta decaying isotopes. He thought that the beta decays are astatine's fault. They were not.
  2. Instead of searching for the element in nature, the scientists created it by bombarding bismuth{{clarify|reason=Which isotope of bismuth? 209?}}--yes. It's always Bi-209 (unless noted)
  3. {{clarify|reason=The decay chains article appears to indicate that astatine wouldn't be part of the fourth decay chain anyway, not that it hasn't been found due to short life or something}} --well, yes. What can I do here?
  • Just making sure this interpretation was correct before I clarified it in the text. Allens (talk) 19:52, 19 February 2012 (UTC)
  1. The iodine acts as a carrier, ensuring that there is sufficient material for laboratory techniques such as filtration and precipitation to work.{{clarify|reason=Wouldn't reactions with iodine be a problem with this technique? If so, that should be remarked on}}-- Unlikely. Even the text says that iodine and astatine react only in vapor state; even using only simple logic, iodine won't work as a carrier for gaseous astatine (its boiling point is lower); otherwise, their reaction is not a problem.
  • Actually, it also says they react in water, but provided it isn't in water, I suppose that would work. Allens (talk) 19:52, 19 February 2012 (UTC)
Well, I wasn't thinking of water. You need a carrier to handle the small pick of astatine easily (such as move in the space, keep, etc.). If you dissolve it in water...you can then just move the water.
(Always thought this is it, but this is only a part of story. Anyway the text says it needs a I2/I- solution. So if no iodides are present, the reaction won't go. If even they are formed somehow during the reaction... you can separate the ionic astatide and AtI chemically...it's not gonna be a problem)--R8R Gtrs (talk) 16:47, 12 March 2012 (UTC)
Makes sense. I'll try to fit this into the text (possibly in a note). Allens (talk | contribs) 17:08, 12 March 2012 (UTC)
  1. camera{{clarify|reason=I'm reasonably certain this isn't the standard meaning of "camera"...}}-- Sure, it's not about the thing you take photos with :) "Camera" may be replaced with "cell" maybe, but this usage of the word also exists.
  • "Cell" has enough meanings as "something closed from the environment" that it seems to work - thanks! Allens (talk | contribs) 22:17, 21 February 2012 (UTC)
  1. to be fixedoxysalts{{clarify|reason=Example formulae would be nice here, since there's no "oxysalts" article}}-- I'll watch later for exact referenced examples. In general, this is a scientific jargon word which commonly refers to salts that contain (usually in the anion) oxygen, such as BaSO4, CaCO3, etc.
  • I can stick in something like "oxysalts (oxygen-containing salts)" and expand it later with referenced examples. Allens (talk) 19:52, 19 February 2012 (UTC)
How about just "oxygen-containing salts ('oxysalts')"? Making the readers understand before giving such hard words is better than the reverse, and I'd prefer that to read.
  • Normally, I would definitely agree... but in this case it's saying "silver(I), thallium(I) or caesium oxysalts", so that would be "silver(I), thallium(I) or caesium oxygen-containing salts ('oxysalts')", which at least to me is not clear on, among other things, what an oxysalt is (does it have something to do with silver/thallium/caesium?). Any thoughts?

Allens (talk | contribs) 22:17, 21 February 2012 (UTC)

Here are the examples: Tl2Cr2O7, Ag2Cr2O7, silver iodates, cesium heteropolytungstates (CsxH3–xPW12O40), all hardly soluble. It'll maybe work as "with several silver(I), thallium(I) or caesium oxygen-containing salts, such as thallium(I) dichromate or silver(I) iodates, to form cationic astatine." Note to self: We can also say that the cation is hydrated in a solution (as, for example, H2OAt+).
  1. a coordination selenocarbamide{{clarify|reason=A note with a definition would be nice here}}--Sure? No book I've seen does; should we? (besides, I don't yet know myself, but may lurk if you confirm)
  • Well, otherwise the reader is left going "huh?"... for some reason, Google seems to think selenourea is one, BTW. No idea if it's correct or not, but searching for "selenocarbamide" gives a whole bunch of selenourea results... Allens (talk) 19:52, 19 February 2012 (UTC)
Google often picks unrelated but similar words if the one you typed in is rare. (Will figure the definite answer later; the original source has left me "huh?" as well, BTW)R8R Gtrs (talk) 18:53, 27 February 2012 (UTC)
Understand.... Allens (talk | contribs) 19:09, 27 February 2012 (UTC)
Looked up. The compound, also called "selenourea," is the selenium analog of urea ("carbamide"), with oxygen replaced with selenium.--R8R Gtrs (talk) 16:02, 4 March 2012 (UTC)
Should we replace selenocarbamine with selenourea, or just link it to selenourea? I'd say the former, provided there aren't any problems about referencing. (Sorry about the delay - I need to trim down my watchlist...) Allens (talk | contribs) 20:56, 7 March 2012 (UTC)
From my point, this would be no problem (if a text says, say, "Federal Republic of Germany," there's no problem to replace it with the term "Germany," which (in context) has the exactly same meaning. My guess is both replacing "selenocarbamine" with "selenourea" and adding a wikilink. You're not the one to apologize-- excuse me for this (I just couldn't edit Wiki, had no time...underslept).--R8R Gtrs (talk) 16:47, 12 March 2012 (UTC)
Understood fully! Done. Allens (talk | contribs) 17:08, 12 March 2012 (UTC)
  1. bismuth oxide is pressed into{{clarify|reason=copper is not normally liquid}}--The original work (in Russian) uses the verb "впрессовывать," which Google Translate refers to as "pressed [sic] into." (I'd use the same verb) If you've got a very small ball of tungsten carbide (just an example of a very strong substance) and a wooden board, you can apply a strong force and the ball will stuck. This is what I mean. You can pick up any verb, I just can't think of one.
  • Hmm... "forced into", perhaps? "forcibly fused with"? Allens (talk) 19:52, 19 February 2012 (UTC)
Any would probably do :)--R8R Gtrs (talk) 13:05, 21 February 2012 (UTC)
  1. to be fixedcollected on a water-cooled surface,{{clarify|reason=Made of what material?}}--Similarly, will check later
Added the info into the text (it was platinum)--R8R Gtrs (talk) 18:32, 3 March 2012 (UTC)
Ah, it does turn out to be important (nobody'd want to use platinum otherwise!) - I suspected it was. Allens (talk | contribs) 21:45, 3 March 2012 (UTC)

Sorry, little time on hands. Hope I satisfied you (at least mostly), don't hesitate to keep asking--R8R Gtrs (talk) 19:23, 19 February 2012 (UTC)

  • Very helpful, thanks! Understand on little time on hands - I am currently procrastinating before grading... Allens (talk) 19:52, 19 February 2012 (UTC)
  1. is chemically a [[hydride]] rather than a [[halide]];{{Contradict-inline|article=Hydrogen astatide|date=February 2012|reason=That article appears to indicate this is a halide}}-- The chemical meaning of the "-ide" meaning is that it is the anion composed on one element in salts, and the more electronegative atom or polyatomic functional group composed on one element. Historically or traditionally, it was named "hydrogen astatide" and is still in literature similarly to other halogens. IUPAC nomenclature also recommends "hydrogen astatide" (or "astatidohydrogen," or "astatane," the second is the same as the first but is specific for the molecular form, and the last is just for HAt, not implying anything). The fact the hydrogen is the electronegative one was found out later. Even HUus may not be called hydride once synthesized (referred commonly just as H(117) now). Who knows?
  2. bismuth is composed of only one isotope, bismuth-209,{{Contradict-inline|article=Bismuth#Isotopes|date=February 2012|reason=The article says there are multiple isotopes of bismuth}}--Well, yes, but for the real word there's only Bi-209. (There's no natural astatine from the same point of view, you'll never mine astatine) Do with this what you find the best.
  • OK. I see; the other long-lived bismuth isotopes aren't on any naturally-occurring decay chains - the Isotopes of bismuth article is (slightly) clearer on this than the Bismuth article. Allens (talk | contribs) 22:17, 21 February 2012 (UTC)

(More to come)

If I missed something, please, add the other ones here as well. Will check the book soon, and complete the rest.--R8R Gtrs (talk) 13:05, 21 February 2012 (UTC)

Here are a few more:

  1. The target is kept under a chemically neutral nitrogen atmosphere - I had earlier had a clarify on this, on the basis that astatine is said above to react with nitrogen, but I'm thinking this isn't going to be a concern since almost all astatine formed will not be on the surface (as well as that the conditions are probably not ones under which nitrogen and astatine react, given how stable nitrogen tends to be).
It never says that At2 and N2 react. There are just N-At bonds. (Also: Fluorine reaction with nitrogen is favorable (energy released), but that doesn't work for chlorine already. Even the N2+F2 reaction occurs only at electric discharge. On the other end, metals with similar electronegativity don't react with N2. So don't think of N2+At2 reaction :) )
  1. AtBr requires, aside from astatine, an iodine/iodine monobromide/bromide solution.[why?]
Didn't check (yet), but more than sure the explanation will be too hard (contrast with the text). IMO, it's an example of something can be explained but it's better not to. Same probably applies to the vessel issue.--R8R Gtrs (talk) 13:26, 14 March 2012 (UTC)
No problem; just looking for things that might be asked during a FA review. Allens (talk | contribs) 13:49, 14 March 2012 (UTC)
I understand (and thanks for that!); although, I'll try to use the same hint there.--R8R Gtrs (talk) 14:46, 14 March 2012 (UTC)
  1. No astatine fluoride has been discovered yet, and although its synthesis is thought to be possible, it may require a liquid halogen fluoride solvent;[why?] - normally, the problem is avoiding fluorine reacting with things, not getting it to react with them, from what I know of the subject...
You're right. (Things that come to my mind: fluorine isn't very interesting to try (you said why). Rutherfordium, for example, was tried with chlorine and bromine (corresponding Zr and Hf salts are not ionic, but volatile), not fluorine. This may be specific for fluorine, don't forget it reacts with almost anything. Maybe they tried the wrong conditions and fluorine reacted with anything else before getting to astatine. Or whatever)
  1. which is put in a U-like quartz vessel.[why?] - why quartz? Why U-like - and, come to think of it, exactly what does that mean? A U-shaped cavity, or what?

The book doesn't say. The U-like is ... like communicating vessels? I mean, the shape. Why this shape? Maybe it's because in the communicating vessels, if you can fill it with mercury and then in one end add water, the level of liquid (the two don't dissolve in each other) won't the the same (have no idea why this helps, though). Why quartz? Maybe 'cause it doesn't change physical properties on quite high temperatures, doesn't even interact with astatine (unlike, say, gold) and is inert chemically (also quite cheap; not sure this one matters).

  1. alpha particles are collided with bismuth. Even though there is only one bismuth isotope used, bismuth-209, the reaction may occur in three possible ways, producing 209At, 210At, and 211At. In order to eliminate the undesired nuclides, the maximum energy of the particle accelerator is set to 28 MeV - section, under synthesis, appears to be uncited.
Gave a ref and added a little more text (please have a look)--R8R Gtrs (talk) 19:37, 2 March 2012 (UTC)

Thanks... Allens (talk | contribs) 22:17, 21 February 2012 (UTC)

Isotopes table[edit]

I have not watched the article lately but my guess is that the table in the isotopes section is waaay to advanced for the purpose of a general article like this one. I suggest moving it into the isotopes article and leave behind a trimmed down version (without the mass excesses). Nergaal (talk) 04:03, 28 February 2012 (UTC)

Look. From my point of view, it is fine now. For an element we can talk hours about (any primordial one counts), there is no particular need to have a long Isotopes section. There's not that much to say about At, though, so I added a quite large discussion on the topic. and the table is for illustration. We could cut the isotope itself and daughter mass excesses, but we certainly have to keep the alpha energy decays. Again, from my point of view. You're a more experienced editor, you're more likely to be right. Agree with me? Or what? :)--R8R Gtrs (talk) 18:40, 2 March 2012 (UTC)
I would normally say to move the material into the isotopes article - except that:
  • Its radioactive decay (and alpha decay at that) is one of the two main things of interest with astatine (the other being the chemical behavior of the heaviest halogen); and
  • Only one isotope is of interest regarding the alpha decay.
Therefore, it seems appropriate to talk about isotopes more intensely than usual. (No pun intended regarding intensities of decay energy...) Regarding the mass excesses, I'd say that if those wind up being important in its alpha decay probabilities and energies, then keep them in the main article; otherwise, move as excessive (;-}) to the isotopes article. Allens (talk | contribs) 21:09, 2 March 2012 (UTC)
Mass excesses are needed to determine the decay energy. Here's in short how: You can weight the parent atom and the daughters (then sum masses of daughters). Given the masses of a proton and a neutron, you can figure what is the difference between masses of 85 unbound protons and 126 unbound neutrons. And calculate that of them all a in single bound system (<su p>211At nucleus). The difference (amu used for practical purposes, although some love SI kilogram perversions... I usually do too, but not with atoms) Then you can find the difference of masses or, equivalently (due to the same numbers of nucleons), mass excesses between 211At nucleus and its daughters, 207Bi and 4He nuclei. And according to the famous E=mc2 (perfectly fine here) formula, calculate into energy, joules or electronvolts. Originally put them into the article just not to give the info, but also to give where it comes from, like the table explains where the alpha half-lives come from. (Figures need to be corrected significantly).
Personally, I'll be fine with either keeping or removing the mass excesses--R8R Gtrs (talk) 18:53, 3 March 2012 (UTC)
Ooh, one more: the masses excesses are easy to cite. without them, just with reaction energy released, we don't have a cite nor a common way to calculate it. So am now in favor of keeping it (hate it when rules lead over readability, but this is the life)--R8R Gtrs (talk) 19:47, 3 March 2012 (UTC)
Good point. Something in the back of my head was telling me they were important for the energies; dunno about the probabilities. Allens (talk | contribs) 22:13, 3 March 2012 (UTC)


Yes, they are useful, but this article is a review on the element. That is why there is a
Main article: Isotopes of astatine
link at the beginning of the section. Any additional information should me moved to the isotopes sub-article if this article is going to be put for FAC. Nergaal (talk) 21:33, 4 March 2012 (UTC)
Could you take a look around for something to cite that has the reaction energy released for each? Thanks! Allens (talk | contribs) 21:08, 7 March 2012 (UTC)

Commas and periods, and the quotation marks[edit]

Are commas and periods in- or outside the quotation marks? Originally tried to keep them in, but now see both variants. Sure I ain't no native English speaker to judge myself. But having looked over the Net, I noticed that all American cites I had seen, had told to put it in. Talked to another American about this before. He seems to have agreed (although it didn't affect his writing any after). So you tell me. Maybe it varies by state or whatever. I don't know for sure, but what I know is "keep it in no matter what." What would you say? Interested, R8R Gtrs (talk) 21:19, 3 March 2012 (UTC)

The standard on Wikipedia is to put them inside if the original quote had them, but outside otherwise - see MOS:LQ. Not having the sources of the quotes myself, I can't tell which to do unless for some reason I shorten a quote. Allens (talk | contribs) 21:33, 3 March 2012 (UTC)
Ooh. Wikipedia has own standards. Didn't know, though; thanks. Will have in mind any further.
Are there any real quotations? --R8R Gtrs (talk) 15:44, 4 March 2012 (UTC)
Quite welcome. Good question; I'll take a look... Allens (talk | contribs) 20:57, 7 March 2012 (UTC)
There are a few in the history section, depending on how you look at it; I've corrected one instance since I doubt that the original name of "anglo-helvetium" included a comma. I noted that, in references done by the wiki-pseudo-standard "cite book/journal" format, ending periods are after the quote marks (admittedly probably difficult to program it other ways, given that the separator is configurable as something other than a period), so I'm thinking they should probably go outside when it isn't a real quote, to keep things consistent. Allens (talk | contribs) 21:05, 7 March 2012 (UTC)

Picture - spectrum?[edit]

Are there any (ideally colored) spectrums available for astatine or one of its compounds (e.g., HAt)? If so, could that be used as a picture? Allens (talk | contribs) 14:05, 14 March 2012 (UTC)

Hmm. There must be some, but I have no idea how to get it. (Will try sometime later, but this is a nice addition rather than necessary, as few articles use it (not even all stable elements FAs!))--R8R Gtrs (talk) 15:10, 14 March 2012 (UTC)
Understand; I was thinking of this as a partial substitute for a picture of the element... Allens (talk | contribs) 15:59, 14 March 2012 (UTC)
There's probably no astatine spectrum. This site admits there was no info available (even though they got even for Es and a single Fr line)--R8R Gtrs (talk) 12:51, 8 April 2012 (UTC)

Diatomic astatine?[edit]

The general characteristics section notes that, 'Like other halogens, it is composed of diatomic At2 molecules under standard conditions.[6]' Has the right reference to support this statement been given? In the reference in question, Zuckerman & Hagen 1989 (p. 21) note that, 'There is little evidence for the existence of diastatine (At2).' They then say that, in respect of the claimed identification of At2 in a radiogaschromotographic study, 'the identification must be considered questionable'.

The uncertain existence of diatomic astatine is also mentioned in the Gmelin handbook on At (1985, pp. 110, 116). Gmelin refers to two claims for the existence of diatomic At and then comments, 'As several authors have pointed out, the existence of molecular astatine is excluded by its extremely low concentrations under ordinary conditions of chemical experiments. Furthermore, the formation of At2 does not seem to be realistic because any reaction which tends to split the At2 molecule becomes thermodynamically favored at these low concentrations.'

There is also a discussion at Talk:Diatomic_molecule#Astatine which notes that according to the CRC Handbook of Chemistry and Physics, it is not yet known whether astatine forms diatomic astatine molecules. Sandbh (talk) 06:55, 24 March 2012 (UTC)

Thank you very much for the noting! I must've mistaken the exact reference when citing. Checked up your info. You seem to be right. Am removing statement it is At2.--R8R Gtrs (talk) 13:06, 24 March 2012 (UTC)
Wouldn't this depend on concentration, which is not specified under the standard conditions discussed in the article linked to standard conditions? Allens (talk | contribs) 13:47, 24 March 2012 (UTC)
R8R, you're welcome. The sententence in question now reads as: 'Another notable difference from the other halogens is that astatine may not form diatomic molecules under standard conditions.[10]' I'm not sure this counts as a difference if the best that can be said is that such a difference *may* be so. It *may* turn out that such a difference does not exist. Nobody knows yet. That is the real difference worth noting: We know that the other halogens form diatomic molecules; we don't know for sure if At can and, if so, under what conditions. The sentence in question might be better expressed something like this:
Unlike its lighter congeners, the crystalline structure of astatine has not been determined (Donohue 1982, p. 400). Nor has it been established with any certainty as to whether astatine will form a diatomic molecule At2 and, if so, under what conditions (Vasáros L & Berei K 1985 pp. 110, 166; Zuckerman & Hagen 1989, p. 21; Meyers 2002, p. 202)
References: Donohue J 1982, 'The structures of the elements,' Robert E. Krieger, Malabar, Florida, ISBN 0-89874-230-7; Vasáros L & Berei K 1985, 'General properties of astatine', in Kugler HK & Keller C (eds) 1985, Gmelin handbook of inorganic and organometallic chemistry, 8th ed., 'At, Astatine', system no. 8a, Springer-Verlag, Berlin, ISBN 3-540-93516-9 — Preceding unsigned comment added by Sandbh (talkcontribs) 06:03, 25 March 2012 (UTC)
Well, the source I got states (not word-by-word, but keeping the sense), "All the halogens form diatomic molecules (except astatine)." It is also newer than most your sources (except for Meyers 2002, which my source is). I dunno... will say no diatomic molecules, simply as the most modern.--R8R Gtrs (talk) 11:17, 25 March 2012 (UTC)
No. It is not accurate to say that, 'Another notable difference from the other halogens is that astatine does not form diatomic molecules under standard conditions.' Nobody knows if At is or is not capable of forming a diatomic molecule. It may be able to; it may not be able to. The best that can be said is as follows: 'Another notable difference from the other halogens is that evidence for the existence of diatomic astatine is sparse and inconclusive (Vasáros L & Berei K 1985 pp. 110, 166; Zuckerman & Hagen 1989, p. 21; Meyers 2002, p. 202). Sandbh (talk) 10:18, 26 March 2012 (UTC)

Here's my point: I'm picking the newest ref up (most modern means most reliable, given same quality of true science books). The Google snippet says, "(except astatine)."It does not mean astatine may not form, it means, it does not form. And long as the source says no and not maybe, it is no and not maybe. (this is one of the basic rules of Wiki) If you've got the whole book dand it contradicts itself, then go ahead. Otherwise, I'd leave it as it is.R8R Gtrs (talk) 13:57, 26 March 2012 (UTC)

I think what is happening is that in the literature, extrapolations, theoretical predictions and claims, are being treated interchangeably. That it is, it is reasonably plausible to suggest the likely existence of diatomic astatine based on the the known existence of the ligher diatomic halogens. There are also lots of theoretical predictions as to the properties of diatomic astatine. And there are at least three papers claiming to have detected diatomic astatine, although there are more references disputing these claims. OTOH, you can pick up a beefy reference like Inorganic Chemistry, by Housecroft and Sharpe (2008, 3rd ed.) and they refer to diatomic astatine as if it was no big deal: 'Tracer studies (which are the only sources of information about the element) show that At2 is less volatile than I2' (p. 533). I'll see if I can post an edit that reflects this murky state of affairs. Sandbh (talk) 07:46, 29 March 2012 (UTC)
I've drafted an edit for the 2nd paragraph of the general characteristic section that keeps the same good structure but adds more content, plus older and later references, addressing the color and diatomicity questions. It's taking a while to get the wording clear and to check the details of the references, some of which are obscure (in French; in journals with similar but changed names mid-stream and no electronic access; hard to find conference proceedings). Will post soon, in between other obligations. Color and diatomicity remain open questions, with some good references going both ways in each case.Sandbh (talk) 13:46, 30 March 2012 (UTC)
Yes, many references seem to present extrapolations of the properties of astatine from bromine and iodine as if they were real measurements. Mendeleev would have called this predicting the properties of eka-iodine, and it should not be taken too seriously in 2012.
For the tracer method mentioned by Housecroft and Sharpe (p.469 in the 2nd edn 2005), I wonder how the original authors proved they had At2 and not AtI, which would be the expected form of a trace of radioactive astatine in I2. Anyway, if some papers claim to have detected At2 and others contest the claim, then WP:NPOV requires that we cite both sides of the controversy.
On the other hand, the Separation section of the article claims that it is possible by a simple cold-finger method to enrich astatine content to 30%. If this is true, then the detection of At2 is more credible. The reference given is a 1966 Russian analytical chemistry book by Lavrukhina and Pozdnyakov. Perhaps R8R Gtrs can find this Russian book and consider whether the 30% claim seems justified.
As I understand it from reading Gmelin (p. 195) the reference to a 30% yield is a reference to the "yield of the yield" i.e. 'Experiments with astatine are restricted to the tracer scale because of its short half-life and the low yield that can be achieved with the [required] nuclear reactions…The largest single batch produced seems to have been 50 nanograms. The highest concentration applied in experiments seems to be 10–8 M, normally solutions <= 10–10 M in astatine have been used.' Gmelin goes on to note that chemical experiments with larger amounts of At would be 'impossible' on account of radiation induced intense self-heating. As well as having to deal with high radioactivity, the solvent would boil away. In essence, 30 per cent of not much is not much at all. Sandbh (talk) 11:52, 31 March 2012 (UTC)
Yes, it is so. 30% of astatine produced can be separated. Not 30% of helium used turns into astatine.--R8R Gtrs (talk) 11:58, 2 April 2012 (UTC)
Also Sandbh mentioned French references above. If these references are accessible online, I can help with the French. Dirac66 (talk) 02:11, 31 March 2012 (UTC)
Appreciate the offer Dirac66. Not required on this occasion. Thanks all the same Sandbh (talk) 11:07, 31 March 2012 (UTC)
OK. I think you have done a good job of describing the state of knowledge about astatine and the reasons why we know so little. Dirac66 (talk) 18:53, 31 March 2012 (UTC)
Thank you. Building on good work by others. Sandbh (talk) 00:33, 1 April 2012 (UTC)
I've done some copyediting (more will be needed, such as on the reference formatting - not just in what you added; I spotted some other inconsistencies). Could someone please translate "Etude de la formation en phase gazeuse de composés interhalogénés d'astate par thermochromatographie"? I'd like to put a trans_title English translation with that reference. Thanks! Allens (talk | contribs) 20:39, 31 March 2012 (UTC)
Translation from French as requested: Study of the gas-phase formation of interhalogen compounds of astatine by thermochromatography. The word thermochromatography is defined here in Wiktionary.Dirac66 (talk) 23:11, 31 March 2012 (UTC)
Thanks! Allens (talk | contribs) 23:49, 31 March 2012 (UTC)
There are also a few other clarifications and translations (from German) needed for the references - I've marked these. Thanks! Allens (talk | contribs) 22:44, 31 March 2012 (UTC)
Beaut, thanks for your polished edits. Clarifications to follow soon. Sandbh (talk) 00:33, 1 April 2012 (UTC)
German translations added--R8R Gtrs (talk) 18:58, 1 April 2012 (UTC)
Thanks very much to all on the clarifications, translations, and compliment to my edits :-}! Allens (talk | contribs) 19:17, 1 April 2012 (UTC)

Bond energy value in gas[edit]

There is a value on a Webelements page of 80 kJ/mol for the At-At bond energy in gas-phase diatomic At2. Not under standard conditions of course but still worth noting in the article if it is true at higher T or lower P. We should however have a source with reference to the original experiment (or calculation). Dirac66 (talk) 19:20, 26 March 2012 (UTC)

They cite CRC Handbook, 81st ed. I've got 84th :) They say it's for 298 K (25 deg C), rather than for gas phase. ~80 doesn't seem much. Analogous Li-Li in Li2 value is ~110 (110.21±4), but lithium is certainly a metal. Can this be a partial conclusion of that it's not At2 at STP (not for the article, just for myself)? [Comment by R8R Gtrs 27 March 2012]
Li is a metallic solid at 298 K but the vapor at high T has Li2 molecules. For At at 298 K one cannot predict the most stable form just from the value of the bond energy. It would depend on all the energy and entropy terms involved in forming each possible form, so we need experimental data or at least a serious quantum-mechanical computation.
And thank you for noticing that Webelements cites the CRC Handbook. I have a much older 60th edition (1979-80!), but it's in there with the original reference: J.Drowart and R.E.Honig, J.Phys.Chem. 61, 980 (1957). So I looked up this paper and found that the authors did not actually do any measurement on astatine! Their table has diatomic molecules for 9 elements which they measured, 27 elements with previous literature values, and 5 elements (Al, At, Be, In, Tl) which they just estimated by interpolation (or extrapolation) vs. atomic number. So the value for At2 cannot be taken very seriously, and in particular does not imply that diatomic At2 has actually been observed. Now that I know it was just a rough estimate and not well justified, I conclude that this value should not be cited in Wikipedia. Dirac66 (talk) 20:34, 27 March 2012 (UTC)
All metals form polyatomic molecules when gases, don't they? (Hg is the odd one, but I very basically imagine why, and am sure you know why) It was just data for 298 K, not gas. Maybe they isolated two single atoms at the T, although there must be an easier way to get the info... Well, it's not the point. Sorry to know it's gonna be that complicated. But! If the calculations are needed, then the first one to do this would probably know what astatine at STP is, structurally. I googled heavily (and will again in some very near future), but found no such calculations. And I can believe none did the empiric crystal structure work. Determining melting and boiling point is actually easier to do. You only need to heat the thing and be careful-- to a not so high T (while separating, it's hotter: this is partially a factor for the separation to work). None photographed astatine either (even given that the modern science can photograph discrete molecules!)
Pfft.. they call themselves scientists :) Just kidding. They probably just needed to fill in an empty space. Sorry that it's just an estimate (although this could be guessed-- other values are given exact or within a small fixed range, not just "~80"). Then, we won't sure cite it. But I still don't think 80 sounds much anyway :)
And thanks for taking part...I find the great extent of your knowledge very useful, giving thus the owing credits. Were I ever that smart, I'd be quite proud of myself--R8R Gtrs (talk) 18:29, 28 March 2012 (UTC)
Apparently not all metals form polyatomic molecules when gases. Sugden (1930, p. 173) said that the alkali metals, silver, zinc, cadmium, (mercury) and thallium were monatomic, and also commented, on the basis of then scanty evidence, that the transition metals were monatomic. Dunstan (1968, p. 431) asserts that 'Vapours of true metals are monatomic.' No further explanation is provided as to what is meant by the expression 'true metal'. Timms and Turney (1977, p. 54) state that 'Most transition metals give monatomic vapors, but dimers and polymers form a small fraction of the vapors of many of the Main Group metals'. Wiberg 2001 (pp. 1097, 1294) says of the alkali metals that, 'The vapors contain primarily metals atoms but, in contrast to the alkaline earth vapors, they also contain some diatomic metals' and, later, that zinc and cadmium vapours are monatomic. Sandbh (talk) 12:18, 29 March 2012 (UTC)
  • Dunstan S 1968, Principles of chemistry, D. Van Nostrand, London
  • Sugden S 1930, The parachor and valency, George Routledge, London
  • Timms PL & Turney TW 1977, 'Metal atom synthesis of organometallic compounds', in FGA Stone (ed.), Advances in organometallic chemistry, vol. 15, pp. 53–112
  • Wiberg N 2001, Inorganic chemistry, Academic Press, San Diego
Then I guess an article needs to be fixed: Relativistic quantum chemistry. "In the gas phase mercury is alone in metals in that it is quite typically found in a monomeric form as Hg(g)."--R8R Gtrs (talk) 18:58, 1 April 2012 (UTC)
Strange. I was just reading Enthalpy of vaporization and it says, 'metals...often form covalently bonded molecules in the gas phase'. Odd (and annoying) that neither extract is supported by a citation. Sandbh (talk) 13:15, 2 April 2012 (UTC)

Solid state structure if not diatomic?[edit]

As for the solid at standard conditions, if it does not contain diatomic molecules, it would be interesting to know the true structure. Perhaps something simple like bcc or fcc? There was apparently enough sample to determine a melting point, so perhaps someone has done a crystallographic structure? Dirac66 (talk) 19:20, 26 March 2012 (UTC)

Vasáros & Berei, in Gmelin (1985) say that the thermodynamic properties of At species have only been estimated by various theoretical and and empirical calculations.
I've haven't been able to find any speculation in the literature as to the possible crystallographic structure of solid At. Extrapolating from the Goldhammer-Herzfeld metallicity values, per Edwards and Sienko (1983), for F, Cl, Br, and I gives a value for At of around 1.25, which is well into the metal range. This is also consistent with Siekierski and Burgess (2002, pp. 65, 122), who contend or presume that astatine would be a metal if it could form a condensed phase. However this is contradicted by Batsanov (1971, p. 811) who gives a calculated band gap energy for astatine of 0.7 eV, implying that it is semiconductor. Edwards & Sienko only went as far as saying that astatine is probably a semi-metal i.e. a metalloid. Throw possible relativistic effects into this mix, as with Hg and Po, and who knows.
As to obtaining enough of a sample of solid astatine to enable the determination of its crystallographic structure, Emsley (2001, p. 48) says that a visible piece of astatine would be immediately and completely vaporized because of the heat generated by its intense radioactivity. Greenwood & Earnshaw (2002, p. 885) say that 'weighable amounts of the element cannot be prepared and no bulk properties are known.' Kean (2011, p. 333) comments that 'No one will likely ever produce a visible sample of astatine…'.
It is interesting and frustrating question.
Given nano-tech I am surprised that the solid-state structure still seems to be an open question. Sandbh (talk) 09:37, 29 March 2012 (UTC)
  • Batsanov SS 1971, 'Quantitative characteristics of bond metallicity in crystals', Journal of Structural Chemistry, vol. 12, no. 5, pp. 809–813
  • Edwards PP & Sienko MJ 1983, 'On the occurrence of metallic character in the periodic table of the elements', Journal of Chemical Education, vol. 60, no. 9, pp. 691–696
  • Emsley J 2001, Nature's building blocks: An A–Z guide to the elements, Oxford University, Oxford
  • Greenwood NN & Earnshaw A 2002, Chemistry of the elements, 2nd ed., Butterworth-Heinemann, Oxford
  • Kean S 2011, The Disappearing Spoon, Doubleday, London
  • Siekierski S & Burgess J 2002, Concise chemistry of the elements, Horwood, Chichester
  • Vasáros L & Berei K 1985, 'General properties of astatine', in Kugler HK & Keller C (eds) 1985, Gmelin handbook of inorganic and organometallic chemistry, 8th ed., 'At, Astatine', system no. 8a, Springer-Verlag, Berlin
I have had a brief look yesterday into the possible structural data and found none. It might be worth adding a brief summary of the findings by Sandbh into the article. Safety regulations strengthen roughly every decade, thus what could be done with radioactive solids in the 1970s will not be permitted now. Fundamental science is also in decline, thus there might be no progress in such matters. Materialscientist (talk) 10:04, 29 March 2012 (UTC)
Done. And not happy about the decline in fundamental science :( Sandbh (talk) 11:03, 31 March 2012 (UTC)

Beta plus decay/positron emission[edit]

I don't find anywhere in the text, as opposed to the infobox, anything about that astatine seems to undergo specifically beta plus decay (positron emission) instead of beta minus decay (electron emission). Given that most people (like me) are going to first think of electron emission when they see "beta decay", I would think this needs clarifying. Do all isotopes of astatine that undergo beta decay emit positrons, or just the most stable ones? Allens (talk | contribs) 14:04, 24 March 2012 (UTC)

The chart of all nuclides: black ones are the stable (right ratios). (The X-axis is the neutron number, and the Y-axis is the proton number). The ones below the black (too little protons) are blue, beta minus (above are the pink, beta plus).
The explanation is very very basic, but this is what is enough to understand.
There is some neutron/proton ratio which is the best for an element. Neighboring elements all have such ratios similar. Compare 10B (1) and 11B (1.2), 12C (1) and 13C (1.17), and 14N (1) and 15N (1.14). The nuclides with the ratio too low (too much protons), such as 11C (0.83), 13N (0.86), etc. need to increase it to get stable: thus they decay into 11B and 13C, emitting positrons. The nuclides with the ratio too high (too little protons) emit electrons (similarly).
Back to astatine. There are no stable isotopes, but there are (almost!) beta-stable (i.e., stable against beta, but not any other, decay) isotopes, which primarily alpha decay and β becomes unimportant. These are between ~213 and 215 (yellow means α decay). The lighter ones (too little protons), including the most stable At-209, -210, and -211, thus emit positrons. The ones heavier than these emit primarily electrons (although At-216 to -218 almost unnoticeable).
Now. Basically, I think it is a good idea to add "plus" in each place. Or replace it with "positron emission."--R8R Gtrs (talk) 14:54, 24 March 2012 (UTC)
Thanks! I've added a bit regarding that it's beta plus decay (positron emission) for lighter than astatine-216; I chose to explain a bit further because it's different for astatine-216 and heavier and because it's actually only mentioned once for astatine elements in general. (I'm still trying to decide whether the explanation should be in an (end)note; I currently lean toward no, so as to best explain the mention of beta plus decay later on. Your thoughts?) I gather that electron capture is another version of the same thing (a proton absorbing an electron in order to become a neutron), but happens when there's not enough energy difference to fuel the expulsion of a positron? Allens (talk | contribs) 23:00, 24 March 2012 (UTC)

You see that you need to spend energy to convert a proton into a neutron. But each nuclei has its own mass (and thus energy equivalent). If energy difference between the parent and the daughter is above 2mec2 (me is the mass of an electron; c is the speed of light), there is enough energy to compensate and thus make favorable. If not, then the nucleus does not beta plus decay.

Ah. Of course (headslap) - the mass energy for the positron has to come from someplace, and neutrons are heavier than protons, so it can't come from converting between the two as it can for emitting an electron. Allens (talk | contribs) 16:46, 25 March 2012 (UTC)

Tried to remaster the wording (just to put in more info). Check, please--R8R Gtrs (talk) 11:49, 25 March 2012 (UTC)

Done; minor copyediting later (more for style than anything else), looks good! Allens (talk | contribs) 16:43, 25 March 2012 (UTC)

Colour[edit]

The article currently reads: 'Astatine fits the trend well, being a black solid.[8]'

Unfortunately, this is not so. Reference [8] is erroneous. Macroscopic (visible) quantities of astatine have not yet been prepared. Neither has there been, to my knowledge, any theoretical study in the literature as to the predicted colour of astatine. Sandbh (talk) 10:29, 26 March 2012 (UTC)

Couldn't this be predicted from spectra? Allens (talk | contribs) 12:11, 26 March 2012 (UTC)
Look. You are right about the reference. But if you know why X2 get darker with the atomic number, then you can expect At2 should be black. Therefore, I decided it was OK to find a lame ref. Now, I know astatine may be not At2. You are free to remove this.
Spectra? Well, yes. The color of the element/compound is the opposite to the color it absorbs. For example, iodine absorbs yellow, so (almost) unbound I2 molecules are violet.R8R Gtrs (talk) 13:27, 26 March 2012 (UTC)
I found some other references to solid astatine either being black or having a metallic appearance. None of these references cite original sources. The earliest black reference is from 1960! One of the later refs notes that solid astatine has never been observed and then suggests that it is logical to conclude that it would most likely be black. I think what is happening is that, in some cases, plausible extrapolations based on the colour of the lighter halogens are being presented as statements, without any explanation that they are extrapolations. So the result is a mixture of information, with some references saying the colour of astatine is unknown, and others noting—either as statements or extrapolations—that astatine either has, or probably has, a black or metallic appearance. This diversity of information about astatine is interesting. I'll see if I can post an edit about all of this, including current and new references. Sandbh (talk) 06:58, 29 March 2012 (UTC)
I believe that, rather than wikipedia recirculating speculations, it would be MUCH more valuable for it to state "As yet, no sample of astatine large enough to be viewable with the naked eye have ever been prepared. As such, the colour of bulk astatine remains a subject for speculation" or something like that. Such a statement is MUCH more informative to the reader, it rams home the point that astitine barely occurs in nature and has never been obtained in macroscopic quantities.--feline1 (talk) 13:36, 29 March 2012 (UTC)
Done Sandbh (talk) 10:59, 31 March 2012 (UTC)
The metalloid article has some interesting further info re astatine's nonmetal/metalloid/metal status. Not sure how much (more), if any, of it (that isn't already present) should be in this article. I do believe it has some references that aren't in this article. Allens (talk | contribs) 13:02, 9 April 2012 (UTC)
Oh. And another section of that article discusses periodic table trends and metalloids (on that basis, astatine's a metalloid, as far as I can tell). Currently, that's a citation needed area; I don't know which of the various citations would be useful, not having the texts in question, however... Allens (talk | contribs) 13:15, 9 April 2012 (UTC)
One interesting pieces of information from the metalloid article is that astatine has a relatively large band gap energy, more similar to nonmetals than to metals; IIRC, doesn't that indicate that it wouldn't shine like a metal? Allens (talk | contribs) 13:18, 9 April 2012 (UTC)
In theory, we could limit the addition new info from there not very strictly, I guess (since so little is actually known). There's a very short article saying there are no period 6 "semimetals." (here) And much of such. Also, about band gap energy. If 0.7 eV is a correct figure, then it could shine: germanium (band gap of 0.67 eV) and silicon (>1 eV) shine (if the shine is actually dependent on this). This figure is associated with typical semiconductors. Also, when Eg=0 or is even slightly lower, it indicates the element is still a metalloid (per Russian wiki), so on this basis astatine is probably is metalloid.--R8R Gtrs (talk) 07:57, 10 April 2012 (UTC)
Yes. This is good. Consider iodine, which has a bandgap of ~1.3 eV. Steudel (1977, p. 240) says of iodine that: '...considerable orbital overlap must exist, to form intermolecular, many-center...[sigma] bonds, spread through the layer and populated with delocalized electrons, reflected in the properties of iodine (lustre, color, moderate electrical conductivity).' The appearance of iodine is described as 'Lustrous metallic gray, violet as a gas'. The remarkable picture backs up the metallic appearance---not to be confused with the violet vapours. Based on a reducing halogen band gap with increasing atomic number, a band gap of 0.7 eV for At is quite plausible, as would be a metallic appearance per iodine. Astatine might instead form a metallic structure either due to relativistic effects like in Po, or all by itself due to Goldhammer-Herzfeld criterion ratio being >=1, in which case hello metallic appearance. Sandbh (talk) 10:37, 11 April 2012 (UTC)
  • Steudel R 1977, Chemistry of the non-metals: With an introduction to atomic structure and chemical bonding, Walter de Gruyter, Berlin

Heat of vaporization[edit]

The figure given in the element template box is 40 kJ•mol−1, which seems out of place. Apparently it comes from Webelements, who give the following sources:

  • G.W.C. Kaye and T.H. Laby in Tables of physical and chemical constants, Longman, London, UK, 15th edition, 1993.
  • H. Ellis (Ed.) in Nuffield Advanced Science Book of Data, Longman, London, UK, 1972.
  • A.M. James and M.P. Lord in Macmillan's Chemical and Physical Data, Macmillan, London, UK, 1992.
  • D.R. Lide, (Ed.) in Chemical Rubber Company handbook of chemistry and physics, CRC Press, Boca Raton, Florida, USA, 79th edition, 1998.

Kaye & Laby (available online :) don't give a figure. Ellis (p. 59; available online :) gives a figure of 45.2. CRC 92nd ed (2011) doesn't give a figure. Gmelin (1985, p. 117) cites three estimates, the lowest of these being 50 kJ/mol.

A simple atomic number extrapolation of the figures for the lighter halogens (F 6.51; Cl 20.41; Br 29.96; I 41.57) yields a figure for At of around 49.

I'll check hard copy James & Lord shortly (unless someone has them at hand). Curiously, Wolfram Alpha doesn't give a figure for At, despite listing James & Lord as a reference. Sandbh (talk) 08:37, 1 April 2012 (UTC)

ΔH(vap) is usually obtained from vapor pressure measurements using the Clausius-Clapeyron relation as ΔH(vap) = -R [d ln p/d(1/T)]. So I have plugged the six vapor pressure values in the infobox into the Excel file I use for this problem in intro phys chem, using the linear regression line for the slope, and found 85.4 kJ/mol! Assuming the vapor pressure values are for the solid, this value is actually ΔH(subl) = ΔH(fus) + ΔH(vap), but the result still implies a ΔH(vap) much higher than 40-50 kJ, since fusion always requires much less energy than vaporisation.
For comparison I did the same calculation on iodine. The infobox vapor pressures for iodine lead to ΔH(subl) = 58.7 kJ. The infobox on iodine gives ΔH(fus) = 15.52 kJ, ΔH(vap) = 41.57 kJ, sum = 57.09 kJ.
So here again the question is how was the data actually obtained - for ΔH(vap) AND for vapor pressure. Do we have actual measurements on pure (liquid or solid) astatine, or extrapolations for eka-iodine again? Dirac66 (talk) 15:47, 1 April 2012 (UTC)
Dirac66, yes your figure of 85.4 kJ/mol is spot on: Gmelin gives figures for ΔH(subl) of 86.91 (0 K) and 83.88 (298.15K). And ΔH(fus) = 23.85 @ 575K Sandbh (talk) 13:06, 2 April 2012 (UTC)
What does the scatter for the linear regression line look like? Any odd curvature, dual-line appearance, etc? I'm wondering if some of them are extrapolations and some aren't. Allens (talk | contribs) 17:49, 1 April 2012 (UTC)
No visible scatter at all. All 6 points are right on the line on my computer screen, and Excel gives the correlation coefficient as (-)0.99993. This suggests that the data are not measured vapor pressures, but values calculated from a linear equation. This would also be suggested by the values of p which are 1, 10, 100, 1000, 10000 and 100000 Pa - no one does an experiment like that.
I traced the data to Template:Infobox astatine to Chemical elements data references to Vapor pressures of the elements (data page), which refers to the CRC Handbook 2003 and in turn the AIP Handbook 1972. Perhaps this last source contains the original reference for astatine. If not we could check the source of the vapor pressures for other elements, since these sources gives vapor pressures of many elements at the same pressures. Dirac66 (talk) 20:21, 1 April 2012 (UTC)
The three Gmelin citations for At2 (liquid -->gaseous) are 50.21 (given a b.p. of 543K); 54.39 (590K) and 90.37 (650K).
James & Lord (1992, pp. 449–450), the missing WEL reference, give the following figures: F2 6.54; Cl2 20.41; Br2 29.45; I2 41.8; At 30. Note the figure for At is given for a mole of At atoms, rather than a mole of At2 molecules, as is the case with the other halogens.
The WP figures listed in the element template boxes are: F 6.51; Cl2 20.41; Br2 29.96; I2 41.57; At 40.
The American Institute of Physics (Gray 1972, p. 4–222 et seq.) does not give a figure for At, but lists these figures for the lighter halogens: F2 6.535; Cl2 20.41; Br2: 29.45; I2 41.82
Ellis (2005) says: F 3.27; Cl 10.2; Br 15; I 20.85, and At 45.2, figures which appear to be for moles of atoms (see also below re the apparent source of the At figure).
The WEL figures are F 3.27; Cl 10.2; Br 14.8 I 20.9 and At 40 (the last figure seems out of place).
Stull & Sinke (1956, p. 48) give the following values, in old school units of cal/gfw:
F2 1,562; Cl2 4,878; Br2 7,170; I2 9,979; At2 21,600 (b.p. 650K)
Using the Ellis value for atomic Br gives 21,600/7170 x 30 = 90.3766 for diatomic astatine (= the high Gmelin value, and this is the same source cited by them) or 45.18 for the atom, which is nigh on the Ellis value (above) for At of 45.2.
In conclusion, I cannot find the WEL figure of 40 in any of the references cited by WEL. Nor can I find any values for the heat of vaporization of At in CRC or the AIP handbook.
Under these circumstances I'd be inclined to cite the middle of the Gmelin references, and list it as 'ca. 55', since the associated boiling point (590K) is closest to the commonly cited b.p. for At of 610K. Either that or show the value as 'At least 50', citing Gmelin. Grateful for any further perspectives on any of this. The comments to date have been remarkable!
  • Gray DE 1972, American Institute of Physics handbook, 3rd ed., McGraw Hill
  • Stull DR & Sinke GC 1956, Thermodynamic properties of the elements, Number 18 of the Advances in Chemistry Series, American Chemical Society
BTW, in terms of listing it as 'ca. 55', the {{circa}} template may be of use (c. 55 or c. 55). Allens (talk | contribs) 13:20, 2 April 2012 (UTC)
Can you determine which of all these values were obtained by actual measurements on samples of astatine? Given the difficulty of preparing astatine, I suspect at least some of the values may be just estimates, perhaps using the Clausius-Clapeyron relation with a normal boiling (or sublimation) point and an enthalpy of vaporization (or sublimation) extrapolated from other halogen values. Dirac66 (talk) 20:24, 2 April 2012 (UTC)
Hmm, no. As I understand it, all the figures are estimates.
The Ellis (2005) value comes from Stull & Sinke (1956), who say (p. 11): 'Astatine. These data are entirely estimated by comparison with the other halogens and are intended to serve only until measured data becomes available'.
Gmelin (1985, p. 113) says the thermodynamic properties of At species have only been estimated by various theoretical and empirical calculations. The low figure (50.21) was estimated 'using the empirical parameter Z’ '—no further explanation given. The high figure is that of Stull & Sinke (1956).
The James & Lord (1992) value comes from Cox JD, Wagman DD and Medvedev VA, CODATA key values for thermodynamics, Hemisphere Publishing Corp., New York, 1989. These values are available on line, with no explanation given as to how they were derived. Curiously, astatine is not listed. Sandbh (talk) 13:54, 3 April 2012 (UTC)
Sorry for turning boring now, but the article needs to benefit this discussion. My point is, we can give a range (stated the extreme values are approximations as well) rather then giving a single one (an endash will do). In theory, if we knew a vapor pressure at any given T, we could calculate (approximately) for any other (given the Clapeyron-Mendeleev equation). In practice, we know none, and the article may do without the table (well, unless we get any data). Opinions?--R8R Gtrs (talk) 16:40, 3 April 2012 (UTC)
Thinking about this some more I suggest listing just the middle Gmelin figure of 54.39, which is taken from Glushko VP, Medvedev VA & Bergma GA et al. 1966, Termicheskie Konstanty Veshchestv (Russian), Handbook of Thermal Constants?, part 1, Nauka, Moscow, p. 65. Knowing there is an approximate correlation between boiling point and heat of vaporization I did an x-y scatter plot of these well-known values for the lighter halogens (F2, Cl2, Br2, I2). To my surprise, a power trendline running through the four x-y coordinates shows a perfect (1.0) or near perfect (0.9998) correlation (can this be so?), depending on the precise value used e.g 14.8 or 15 for Br2 heat of vaporization etc. The line itself is almost straight, in fact a straight trend line has a correlation of 0.9994. The values I get for At, with the power trendline, is b.p of 590K = 55.41 and for 610K = 57.49. Given this, I am inclined to cite the value of 54.39, since that is closest to the commonly quoted b.p. for At of 610K. Sandbh (talk) 13:17, 4 April 2012 (UTC)
Even simpler: Termal Constants of Substances. Also, what if there'll be anyone to try to cite another value? We could hide a note it's the most likely per talk or what? If so, that's fine and takes care of my anxiety.--R8R Gtrs (talk) 13:51, 7 April 2012 (UTC)

Melting/boiling point(s)[edit]

The "Estimation chemical form boiling point elementary astatine by radio gas chromatography" article gives an estimated boiling point of At2 (if it exists) of 503 K, partially from experimental evidence (which is below the currently estimated melting point). Does the "Study of the gas-phase formation of interhalogen compounds of astatine by thermochromatography" (translated title) article give any info regarding melting/boiling points, as is implied by "thermochromatography"? Allens (talk | contribs) 15:09, 9 April 2012 (UTC)

I have mentioned the experimental evidence for a lower boiling point; I would much prefer citing a review article, however! Any idea where to find such? Allens (talk | contribs) 15:11, 9 April 2012 (UTC)

These values (575 mp 610 bp) seem to be ubiquitous. Gmelin cites CRC Handbook 62nd ed., 1981/82, p. B-7. They also give values of 575/608 in RA Honig, DA Kramer (RCA Rev. 30 (1969) 285/305; C. A. 71 (1969) No. 64413). Possibly these values were rounded up by CRC? 575/610 seem too 'five-ish' or perhaps it's just a coincidence. Sandbh (talk) 08:18, 10 April 2012 (UTC)

Electronegativity[edit]

Does anyone happen to have (free) access to the following and could post any listing of electronegativities or similar information that it gives?

  • Dolg, M; Kuchle, W; Stoll, H; Preuss, H; Schwerdtfeger, P (1991). "Ab Initio pseudopotentials for Hg to Rn: II. Molecular calculations on the hydrides of Hg to At and the fluorides of Rn". Molecular Physics 74 (6): 1265–1285. doi:10.1080/00268979100102951. 

It is where the book:

is getting its info on Astatine's electronegativity. I'm wondering for the following two reasons:

  1. The latter book is not nearly as clear as one would like on that astatine's electronegativity is below that of hydrogen's.
  2. I'd like to be able to get a set of electronegativities, not just for astatine, so as to update more of Electronegativities of the elements (data page) - otherwise, I'd be left putting in an additional reference column for one element, which is inefficient.

Thanks! Allens (talk | contribs) 14:42, 4 April 2012 (UTC)

Dolg et al. do not list any ENs. They only note in passing that in AtH the negative charge is thought to be on the H atom. A similar observation is made by Saue T, Faegir K & Gropen O 1996, 'Relativistic effects on the bonding of heavy and superheavy hydrogen halides', Chemical Physics Letters, 263 (360–366). ENs are not discussed in that article either. Probably the best that could be said is that the EN of At is commonly taken to have the same value as H, however in HAt the negative charge is thought to be on the H atom. And that, consistent with this, it is interesting to note that the EN of At in the Allred-Rochow scale (1.9) is less than that of H (2.2). Sandbh (talk) 13:13, 5 April 2012 (UTC)
Something like this(?):
The element is often said to have an electronegativity of 2.2 (Pauling scale), since this is stated in Pauling's work.[13] This is lower than that of iodine (2.5 in the original work and 2.66 now)[14] and the same as that of hydrogen. However, in [hydrogen astatide] (HAt) the negative charge is thought to be on the hydrogen atom, implying that this compound should be referred to as astatine hydride.[refs per above] Consistent with this finding, the electronegativity of astatine in the Allred-Rochow scale (1.9) is less than that of hydrogen (2.2).[WEL][Note] Astatine sublimes less readily than iodine, with a lower vapor pressure;[clarification needed] it also dissolves in water better than iodine.[2]
Note: The algorithm used to generate the Allred-Rochow scale fails in the case of hydrogen, since it provides a value that is close to that of oxygen (3.5). Hydrogen is instead assigned a value of 2.2. Despite this shortcoming, the Allred-Rochow scale has achieved a relatively high degree of acceptance. [Smith 1990, p. 135]
Smith DW 1990, Inorganic substances: A prelude to the study of descriptive inorganic chemistry, Cambridge University, Cambridge, ISBN 0-521-33738-0
Sandbh (talk) 00:18, 6 April 2012 (UTC)
Looks good; what's the [WEL] reference? Allens (talk | contribs) 00:28, 6 April 2012 (UTC)
Well, (no pun intended) I couldn't find any Allred-Rochow values on Wikipedia (odd, that) so I thought a link to the relevant Webelements page would do Sandbh (talk) 03:40, 6 April 2012 (UTC)
Two references mentioned above say the negative charge "is thought to be" on the H atom in HAt. Does either mention WHY it is thought to be on H? Dirac66 (talk) 01:30, 6 April 2012 (UTC)
No, neither mention why explicitly or clearly, although all may not be lost. They both discuss such things as relativistic dynamics and spin–orbit interaction. They both use 'traditional tools of quantum mechanics' to predict e.g. bond lengths, disassociation energies, vibrational frequencies and dipole moments in HAt or AtH. For example, Saue et al. say, 'The dipole moment is calculated to be 0.06 D with the negative charge on hydrogen, indicating covalent bonding'. It is quite interesting to note that in Dolg et al., the negative charge is listed as being on the H atom, in both the nonrelativistic(!) and relativistic cases. They in fact say that, '...for a proper discussion of relativistic effects it is necessary to carry out both nonrelativistic and quasirelativistic calculations'. It is pertinent to note that neither of the three refs in question say anything about implications for astatine EN. There is another ref in J. Chem. Ed, vol. 82, no. 11, 2005, by Thayer (pp.1721) who also notes the negative pole is predicted to be on hydrogen, and he adds an exclamation mark to this statement, implying astonishment I guess. Perhaps the reference to the Allred-Rochow scale would be better worded as, 'In this context it is interesting to note that the electronegativity of astatine in the Allred-Rochow scale (1.9) is less than that of hydrogen (2.2).[WEL][Note] Sandbh (talk) 05:55, 6 April 2012 (UTC)
Thanks. Actually this does answer my question, since I meant WHY in the sense of "what is the evidence", rather than "what is the physical reason" which is a much harder question. We can mention in the article that quantum chemical calculations (both relativistic and not) indicate a dipole of 0.06 D with the negative charge on H, suggesting a lower EN for At than for H, with the references of course. This should replace the statement that "experiments have shown that astatine's actual electronegativity is slightly less than that of hydrogen", which is incorrect since there are in fact no experimental data. Dirac66 (talk) 15:20, 6 April 2012 (UTC)
OK. I'll post an edit along the lines of my second proposed form of words. I'm somewhat reluctant to say that these papers actually suggest a lower EN for At, since none do so, but I'd be happy to add something about At's EN in the Allred-Rochow scale, and simply leave it as a contextual observation. Sandbh (talk) 02:41, 7 April 2012 (UTC)
Yes, that would reflect the papers more accurately. Dirac66 (talk) 03:00, 7 April 2012 (UTC)
May I have a word, too? I agree with the decision. Only almost until I clear one point. Electronegativity. Doesn't H charged negatively in HAt denote the greater EN for H? I just read the electronegativity article. It says only EN diff (Pauling) can be measured; the electronegative one of the two compared is guessed by "intuition" (read the text). Doesn't this mean, since in HAt H attracts electrons more strongly, it is the electronegative one? If so, this should also be reflected somehow--R8R Gtrs (talk) 13:06, 7 April 2012 (UTC)
The statement about chemical intuition in the electronegativity article applies to the original Pauling method using dissociation energies, which has a square root in the formula so that the sign is undetermined. However if a more modern experimental or computational method shows that the negative charge is on H, that implies that H is more electronegative. At least this would be true if the negative charge were large enough to be certain of the sign. For a dipole as small as 0.06 D the sign is not too reliable and should be treated as only a suggestion. Dirac66 (talk) 18:08, 7 April 2012 (UTC)

Then I only have to clear why there IS an "uncertainty level" 0.06 D falls into, and I'm done with questions here--R8R Gtrs (talk) 14:23, 8 April 2012 (UTC)

0.06 D is the computed value of the dipole, not the uncertainty. The uncertainty depends on the quantum chemical method used and I don't know how large it is. But intuitively 0.06 D is so small that I expect it to be smaller than the uncertainty so that the sign is probably uncertain. If this is true, then all we can really say is that EN(At) is very close to EN(H), without knowing which is larger. Dirac66 (talk) 14:37, 8 April 2012 (UTC)
In other words, it's likely any reasonable confidence interval includes 0. I'm thinking something like "While astatine is frequently said to have an electronegativity the same as hydrogen's, 2.2 (Pauling scale), some calculations indicate that it may actually be slightly less than hydrogen's. If so, then [material about astatide, etc]". That's a first draft, and rough - something needs to be said about people going from Pauling's work. Allens (talk | contribs) 18:17, 8 April 2012 (UTC)
Oh. And perhaps the infobox should have ~2.2 or c. 2.2 as the Pauling-scale electronegativity? Allens (talk | contribs) 18:25, 8 April 2012 (UTC)
I was actually asking why you think 0.06 D is too little to imply the sign. Lurked. Not easily, but formulated an understanding. Seem to know. Question withdrawn---R8R Gtrs (talk) 20:24, 8 April 2012 (UTC)
I initially supported a proposal to list EN(At) as < 2.2 or somesuch but, upon reflection, I think this may be a step too far. The papers in question only talk about a prediction that the negative charge would be on the H atom, and that this compound would therefore be better called a hydride, rather than an astatide. None of them actually had anything to say about EN(At) which, in the literature, is always listed as 2.2 (revised Pauling). Curiously, I just noticed that Maddock (1956, p. 1076; ref details in main article) says that the polarization of the astatine hydride molecule was discussed in Clark CHD 1936, Proc. Leeds. Phil. Soc. 3, 208–17 (Proceedings of the Leeds Philosophical and Literary Society. Scientific section). It could take a while to hunt that one down, although there may be an entry for it in Chemical Abstracts vol. 30, entry 4760. 1936? Very strange. Sandbh (talk) 05:20, 9 April 2012 (UTC)
We should not go beyond what is actually known, which for astatine is very little. Anything written in 1936 must be a periodic-table extrapolation, since astatine had not yet been discovered then. And most of what has been written since seems to be extrapolated also. I would just say 2.2 (approx.) and delete the nomenclature discussion (astatide vs. hydride). Dirac66 (talk) 11:13, 9 April 2012 (UTC)
Even though "approx" is not in the literature yet astatide v. hydride is? Sandbh (talk) 11:43, 9 April 2012 (UTC)
"Some authors imply" should be enough. This is sweet, we could mention it without labeling this "the absolute and undisputed truth." Also, it seems to me that the previous Char discussion about EN(At) (mentioning both old and new). EN(At) stated everywhere is an approximation. None revised it, unlike those of the stable elements. Francium has a more notable (but similar enough) story.--R8R Gtrs (talk) 11:23, 17 April 2012 (UTC)

Characteristics section[edit]

I posted an edit to this section so as to improve its flow and internal consistency (see also the #22 'Rearrange sections?'). The story it tries to tell is: Context (radioactive; bulk unavailable; periodic table location) → Physical props. (estimations) → Chemical props. (tracer studies). I updated the information about HAt/AtH and the EN of At as per talk. I added a couple of citation needed tags, where I thought these were required. I left out the bit about At dissolving in water better than iodine since this factoid doesn't seem to add anything to the development of any of the paragraphs. I tried to keep the number of paragraghs low, out of respect for my predecessors. The rest of the article will need more work to pare back the information about HAt/AtH, and the EN of At. Sandbh (talk) 05:11, 8 April 2012 (UTC)

Existence of At(VII)[edit]

Some of the recent literature about this is erroneous. Barysz (2010, p. 79) says that this state has not been verified and that earlier claims for AtO4 had also not been verified. She cites a 1964 reference. Atkins et al. (2010, p. 421) say the same thing: 'No evidence for At(VIII) has yet been obtained'.

Gmelin (1985, pp. 112, 192–193), however, notes that the formation of the perastatate ion (AtO4) was reported in 1970 and that its synthesis was replicated and confirmed with new evidence in 1978. Greenwood and Earnshaw (2002, p. 886) write that, 'The perastatate ion, AtO4, was first conclusively prepared by VA Khalkin's group in the USSR 1970 using solid XeF2 in hot NaOH solution at ph ~10.'

  • Atkins P, Overton T, Rourke J, Weller M & Armstrong F 2010, Shriver & Atkins' inorganic chemistry, 5th ed., Oxford University Press, Oxford, ISBN 1-4292-1820-7
  • Barysz M 2010, Relativistic methods for chemists, Springer
  • Gmelin: Kugler HK & Keller C (eds) 1985, Gmelin handbook of inorganic and organometallic chemistry, 8th ed., 'At, Astatine', system no. 8a, Springer-Verlag, Berlin, ISBN 3-540-93516-9
  • Greenwood NN & Earnshaw A 2002, Chemistry of the elements, 2nd ed., Butterworth-Heinemann, ISBN 0-7506-3365-4 — Preceding unsigned comment added by Sandbh (talkcontribs) 08:23, 13 April 2012 (UTC)
The Gmelin ref seems good and belieable. (this doesn't explain why Atkins and his colleagues don't believe in At(VII), though)--R8R Gtrs (talk) 16:48, 18 April 2012 (UTC)
Yes, Gmelin is very good.
Atkins et al. are wrong. I would attribute this to (a) astatine being in the backwaters of chemistry; (b) the need to meet commercial publishing deadlines to get the next edition of their book out, in order to maintain sales; (c) the general practice of repeating what other authors say, who are in the same 'publish or be damned' situation; (d) a little bit of professional blinkers---focussing on and accepting what is thought to be known rather than asking why not; and (e) good faith human error.
This doesn't matter much since probably 99+ per cent of what they say is OK however under this business model the 1 per cent zone can be quite risky.
I reckon the same thing has happened with IBr5; and I know of a few other examples. How about Bresica (1975, p. 137) who said that 'transition metals do not form monatomic anions.' Some thirty years earlier, however, Sommer (1943) had reported the preparation of the yellow transparent compound CsAu. This was subsequently shown to consist of caesium cations (+1) and auride anions (–1), although it took some years for this 'surprising' conclusion to be accepted. (Spicer, Sommer & White 1959, p. 61). Or Brown et al. (2009, p. 137): 'the alkali metal ions (group 1A) always have a +1 charge, and therefore the alkali metals always have an oxidation number of +1 in their compounds.' Whereas the synthesis of a crystalline salt of the sodium anion Na was reported in 1974 (Dye et al.). Or The Encyclopedia Britannica (2008): 'Fluorine is difficult to isolate from its compounds, and in fact it is impossible to free it by chemical means.' Whereas a purely chemical preparation of diatomic fluorine was achieved in 1986 (Christe). And there is also the Journal of Chemical Education, which lists nearly 30 articles about textbook errors.
I don't think any of this matters that much but it is good to be aware of the phenomenon. It gives rise to the disclaimer in front of many books that says something like, 'all errors are our own and we are happy to have this pointed out to us for correction in future editions' etc Sandbh (talk) 05:22, 21 April 2012 (UTC)
  • Brescia F 1975, Fundamentals of chemistry, Academic Press, New York.
  • Brown TL, LeMay HE, Bursten BE, Murphy CJ & Woodward P 2009, Chemistry: The Central Science, 11th ed., Pearson Education, NJ.
  • Christe KO 1986, 'Chemical synthesis of elemental fluorine', Inorganic Chemistry, vol. 25, no. 21, Oct, pp. 3721–3722.
  • Dye JL, Ceraso JM, Tak ML, Barnett BL & Tehan FJ 1974, 'Crystalline salt of the sodium anion (Na)', Journal of the American Chemical Society, vol. 96, no. 2, pp. 608–609.
  • Sommer AH, 'Alloys of Gold with alkali metals', Nature, vol. 152, p. 215.
  • Spicer WE, Sommer AH & White JG 1959, 'Studies of the semiconducting properties of the compound CsAu', Physical Review, vol. 115, no. 1, July 1, pp. 57–62.
Thanks for writing that long piece of text. Everything seems clearer. Know this can be used very carefully only, but it's OK. No questions left and 2+2 finally made 4. Thanks again (no new infos here, just thanks)--R8R Gtrs (talk) 17:10, 21 April 2012 (UTC)
That's great! Thank you for the feedback. Sandbh (talk) 02:40, 22 April 2012 (UTC)

AtI - heaviest interhalogen?[edit]

What about AtI
2
? Or does "interhalogen" not count ions? Allens (talk | contribs) 04:58, 15 April 2012 (UTC)

Yeah, interhalogen refers to the neutral compounds. I don't even know if there's a source for this anion.--Jasper Deng (talk) 05:10, 15 April 2012 (UTC)
There's no and won't be any because this is a lie. IBr5 is way heavier.--R8R Gtrs (talk) 13:05, 16 April 2012 (UTC)
I've corrected it in this and the interhalogen article (as the heaviest known two-atom interhalogen). IBr5 needs adding to the interhalogen article, if you can locate a reference for it. Allens (talk | contribs) 13:56, 16 April 2012 (UTC)
I've never known any poly-atomic interhalogens that didn't have Cl or F as the peripheral atoms.--Jasper Deng (talk) 17:07, 16 April 2012 (UTC)
A few Google snippets: one and two.--R8R Gtrs (talk) 11:15, 17 April 2012 (UTC)
I've added IBr5 to the interhalogen article, with 3 refs from Google Books. There's some disagreement over its color, incidentally. Allens (talk | contribs) 22:48, 17 April 2012 (UTC)
Seems fine: good job. The disagreement over color is not novel: a few rarely seen compounds have analogous ones. (Example-- HTcO4)--R8R Gtrs (talk) 16:44, 18 April 2012 (UTC)
Thanks! I have some suspicion that the colored forms are due to the presence of unreacted iodine or bromide in the older synthesis method(s). It appears that it's currently not synthesized deliberately very much, but shows up in industrial waste, making its color rather hard to pin down in the usual form seen... Allens (talk | contribs) 17:05, 18 April 2012 (UTC)
The disagreement definitely goes from the impurities. (Impurities matter: <1% of the dioxide in thorium metal leads to lowering the m.p. for a few hundreds kelvins) Never explored the topic, so didn't know about wastes. (However, it seems weird if science literature cited the IBr5 wastes color as the true IBr5 color)--R8R Gtrs (talk) 17:17, 18 April 2012 (UTC)

────────────────────────────────────────────────────────────────────────────────────────────────────(We should probably move this discussion to the Talk:Interhalogen page.) The difficulty comes from the scarcity (at least in Google Books) of modern info on IBr5. It used to be used vs diptheria, so there's lots of stuff from 1909 and before on it. Of the two modern references, one just says "crystalline solid" and one (on wastes) says "colorless crystals", unstable on heating, very toxic, and that it's a byproduct of some syntheses. The one from 1909 goes into much, much more detail, including synthesis, it giving off bromine vapors if heated sufficiently, etc. That one also claims that it's liquid at anything above 4C, which may be a matter of the presence of iodine, bromine, and/or water. Except... normally crystallization drives out impurities, right? Allens (talk | contribs) 22:05, 18 April 2012 (UTC)

IBr5 probably hasn't been synthesized, to date. It isn't mentioned in any of the 'majors' (Greenwood & Earnshaw; Cotton & Wilkinson; Wiberg). Sharpe (1956), writing in (the) Supplement to Mellor's comprehensive treatise on inorganic and theoretical chemistry, Supplement II, Part 1, (F, Cl, Br, I, At), p. 742, says: 'The conclusion that there is only one bromide of iodine, IBr (Mellor, II, 122), remains unchallenged.' (Mellor II is available via the Internet archive.) Even so it would be worth making some mention of this situation. Sandbh (talk) 11:24, 19 April 2012 (UTC)
Unless you'd like to do it, I'll put in that some sources claim it hasn't been synthesized. The two modern references (more modern than Sharpe) and the 1909 one all indicate differently, however. It apparently isn't being deliberately synthesized nowadays... Allens (talk | contribs) 13:01, 19 April 2012 (UTC)
Yes, feel free to do so. I suspect that the two later sources may be erroneous. I cannot find any references to IBr5, more modern than Sharpe, in any journals albeit I haven't looked exhaustively. The descriptions of IBr5 sound like what Mellor attributed them to: either a solid mix of ice and IBr or a liquid mix of IBr and an excess of bromine. As well, whilst chemistry always comes up with surprises, I have a hard time conceiving how Br with an EN of 2.96 could lure five electrons away from I with an EN of 2.66, in order to form IBr5. Mind you I haven't looked closely to see if there are any other XY5 or so compounds with comparably small EN differences, that would discount my skepticism. Sandbh (talk) 02:41, 20 April 2012 (UTC)

With hydrogen[edit]

This subsection currently says: "It [AtH/HAt] is easily oxidized: upon the addition of nitric acid (in which astatine is said to exist as At(0) or At+) and silver(I), astatine precipitates only partially as silver(I) astatide (AgAt), or not at all. Iodine, in contrast, precipitates readily as silver(I) iodide." Allens (talk) then asked, "Why does not precipitating well indicate being easily oxidized?"

The relevant extract from Wiberg 2001 (p. 423) is: 'Because hydrogen astatide is readily oxidized, the astatide ion can only be partially precipitated as AgAt after acidification with nitric acid (oxidation) and addition of Ag+ ions.' As I understand it, astatine does not precipiate well as AgAt since upon being acidified by nitric acid any or most astatide (At) ions, which might otherwise be available, are oxidized to At(0) or At+. Whereas, iodine, for example, would still be present in the form of dilute hydroiodic acid (H+I). This is on the basis that the hydrogen halides become less easy to oxidize with reducing atomic number. Hence not precipating well is associated with easy oxidizability. Sandbh (talk) 13:31, 16 April 2012 (UTC)

I've attempted to clarify this, hopefully without doing too much synthesis... Allens (talk | contribs) 14:07, 16 April 2012 (UTC)

Compounds section[edit]

Do we need the subheaders? I wrotetried to write a solid text for each section, small enough to go without subheaders and large enough to have the contents and the composition. The subsections are 1 para long, some terribly short alone (but were fine with the others); the section in whole isn't too long. I just thought that someone who would be to read the article wouldn't look for specifically At-O compounds...why the subheaders? (I didn't even like the Char subheaders, don't feel the need)--R8R Gtrs (talk) 17:00, 18 April 2012 (UTC)

Good question; I'll take a look at the current elements FAs to see if they give any hints. Note that it's possible to have headers without them being in the table of contents, via {{TOC limit}}. Allens (talk | contribs) 17:10, 18 April 2012 (UTC)
A look at the highly-radioactive-element FAs indicates that we should probably move the compounds section (probably without subheaders) into the characteristics section, but keep the characteristics subheaders (including "compounds" as a subheader). About the only difficulty that I can see with this is the table of At-including substances used in cancer treatment, etc - they're compounds of At also... Allens (talk | contribs) 21:41, 18 April 2012 (UTC)
Dunno. Think they're irrelevant. Francium's chemistry is only Fr+, not much to tell, so no separate section. Uuo's chemistry hasn't even been tested, no section either. And we've got a story...--R8R Gtrs (talk) 11:01, 20 April 2012 (UTC)
Hrm - before I saw this, I had already altered it. I was also going off of Technetium, also a (radioactive) FA, with more compounds (and level-4 subheaders for them, admittedly); it has +4, +5, and +7 as common states. If you wish, feel free to alter it back... Allens (talk | contribs) 11:15, 20 April 2012 (UTC)
Less subheads is OK although having them there for a while imposed some content and organizational discipline, I thought. Sandbh (talk) 12:10, 20 April 2012 (UTC)

Archive talk page?[edit]

This talk page is getting rather long, partially with material that's quite old. I've recently set up archiving for Talk:Joan Pujol Garcia, and propose setting it up for this page. I suggest any thread not touched in 30+ days should be archived, plus a maximum 50,000 bytes on the talk page. (Would people prefer the archive box collapsed or not? It's collapsed on the Talk:Joan Pujol Garcia page, if you want to take a look.) Allens (talk | contribs) 21:15, 19 April 2012 (UTC)

I'd prefer a higher limit of ~90 days, that should be enough to get the talk page below 50kB. --Roentgenium111 (talk) 16:42, 20 April 2012 (UTC)
90 days is fine by me. (That limit is in addition to a limit of 50kB, incidentally. I do not have in mind using the additional limit of 10 threads max that I used on the Talk:Joan Pujol Garcia page.) Allens (talk | contribs) 17:01, 20 April 2012 (UTC)
Well, DoubleSharp seems to have done manual archiving. I'm now going to need to figure out how to integrate the manual archives into the automatic version - probably by de-manually archiving it but tagging that material with an archive-now tag to make sure Cluebot III will go ahead and archive it. (I had been waiting to see if anyone else wanted to comment, but it looks like at least three people want archiving, and nobody objects, so...) Allens (talk | contribs) 17:22, 6 May 2012 (UTC)

Astatine-oxygen bonds[edit]

The following (in a note linked off of "The lower oxidation states are a common starting point for astatine–oxygen bonds") is completely unclear regarding +1 oxidation states with oxygen: "This starting with lower oxidation states, however, does not mean that there are no halogen-based astatine complexes in an oxidation state above +1, as well as that there is no oxygen-based astatine species in the oxidation state of +1." Are there, or aren't there, oxygen-based astatine chemical species with a +1 oxidation state? There's a double negative with "does not mean" and "there is no". And what's the relationship between this and starting with lower oxidation states in compounds with oxygen? And, moreover, saying that astatine-oxygen bonds usually begin with lower oxidation states (lower as in not above +1?) doesn't seem to have any particular relationship with whether or not there are "halogen-based astatine complexes in an oxidation state above +1". Once I know these things, I can rewrite it to be clear(er). Thanks! Allens (talk | contribs) 11:23, 20 April 2012 (UTC)

Fast re:
  • Yes, there's a +1 O-based At species: AtO- with 0 to 2 protons linked to the oxygen. HOAt is an acid, H2OAt+ is "protonated acid" (viewing as a hydronium with one H replaced with At is also fine).
  • Yes again, lower as in not above +1. The latter point also makes sense, there's little. Write as you find better, whatever you write will do.--R8R Gtrs (talk) 16:50, 21 April 2012 (UTC)
I've had a go at rewriting this, rather than trying to answer all of the questions individualyl. Easier to do it that way. Now ready for any further refinements. I thought the presentation of Cr2O72– looked a bit odd; the subscriped 2 and 7 don't line up. Sandbh (talk) 02:47, 22 April 2012 (UTC)
How about Cr
2
O2–
7
? Double sharp (talk) 08:31, 6 June 2012 (UTC)

Declaring my copyedit done for now - will keep an eye on and be back when the FA discussion starts up[edit]

As the subject says, I'm declaring my "official"/GOCE copyediting done for now. I'll keep an eye on the article (like copyediting any responses to my clarification requests) and will be back to help out when the FA discussion begins. Allens (talk | contribs) 16:39, 24 May 2012 (UTC)

Yes, the best now. I'm going to be concentrated on another article (I did say this is a side project, didn't I?), sorry, yet watching and sometimes beating the tags again. Thank you very much for your work, you're a great editor; I hope this really is not a "goodbye thanks." Do hope to see you at FAC. --R8R Gtrs (talk) 17:03, 24 May 2012 (UTC)
I certainly don't intend for it to be a "goodbye thanks" (does the other article need copyediting?); quite welcome, and thanks for your praise! Allens (talk | contribs) 21:08, 24 May 2012 (UTC)
Of course I know you don't. Just hoping it won't change. And one doesn't thank for the truth :) The article (fluorine) I guess could use one, but definitely later, there are things to be done before copyediting. I can inform you once I set it up, so you're to decide if it will be interesting for you.--R8R Gtrs (talk) 18:00, 27 May 2012 (UTC)
Please do! Allens (talk | contribs) 14:25, 28 May 2012 (UTC)

The University of California[edit]

In 1945 and earlier, the research university of the University of California was the one in Berkeley, and hence saying anything more than University of California is redundant, misleading, and historically anachronistic.
The only other possible campus of the University of California was its southern division in Los Angeles, which was a teaching institution, and not a research univerisity.
These campuses of the University of California did not exist back then:
The ones in Santa Cruz, Santa Barbara, Riverside, Irvine, San Diego (or La Jolla), Modesto, or Davis. The University of California at San Francisco might have existed, but it wasn't called that. The University of California at Los Angeles might have existed, but it was not a high-level research institution like the one in Berkeley was.
The one in San Francisco was just the medical school, dental school, nursing school, and pharmacy school of the campus in Berkeley.
Also note that its official name has been the University of California at Berkley since sometime in the '70s or '80s.
09:11, 10 August 2012 (UTC) — Preceding unsigned comment added by 98.67.106.59 (talk)

Don't see how it's misleading. It helps clarify what is being talked about. And it is true that it was in Berkeley. It's not completely (my edit summary didn't have this word for some reason) in Berkeley now, after all. Double sharp (talk) 12:55, 10 August 2012 (UTC)

newly discovered info[edit]

I just read an article on the Phys.Org website that may contain some useful information or sources that could be added to this Wikipedia article. 66.18.219.221 (talk) 16:40, 6 July 2013 (UTC)

Neptunium Series[edit]

I am not sure how to interpret this chart of decay products.

Are the times indicated there half-lives? If so, why does Francium have 5 min? The longest half-life I know about is about 20 seconds. Jokem (talk) 00:48, 21 September 2013 (UTC)

Yes, they are half-lives. 221Fr has a 4.9-minute half-life, and 222Fr and 223Fr are even longer-lived (14.2 min and 22.00 min respectively). Ref: [1] (registration required). Double sharp (talk) 03:25, 21 September 2013 (UTC)

Estimation of physical properties[edit]

Following the progression of coloration, the color of Astatine would be darker than black; this points to an explanation of radioactivity as the natural consequence of consistency constraints in the fabric of the universe, where radioactive elements become radioactive by virtue of it being impossible to display the expected physical property because it makes no sense physically speaking. - djb — Preceding unsigned comment added by 64.134.44.153 (talk) 04:38, 7 January 2014 (UTC)

That assumes that At forms diatomic molecules as its most stable allotrope, which is not known for sure to be the case. And also, if your extrapolations produce nonsensical results, then what's more likely: something's wrong with your extrapolation, or with the universe? Double sharp (talk) 05:52, 7 January 2014 (UTC)
The premise of the estimation---that iodine has a black appearance---is also incorrect. Under white light, at room temperature, solid iodine has a silvery metallic appearance. Astatine, being more metallic than iodine, is most likely to have a silvery metallic appearance, or at least a metallic appearance. Sandbh (talk) 09:53, 7 January 2014 (UTC)
I think this extrapolation is using violet gaseous iodine as the colour for iodine, instead of the silvery metallic solid iodine. Double sharp (talk) 12:49, 21 March 2014 (UTC)
(Also, this doesn't really explain why thorium and uranium are radioactive.) Double sharp (talk) 06:06, 19 July 2014 (UTC)

Sourcing[edit]

  • Some of the numbers in the infobox do not appear to be sourced anywhere
    • These can be found from the link at the bottom of the infobox saying "references". Only when these standard references (yes they are WP pages but all they have are data values from various sources) don't give a value does the infobox state a reference. This is used in most WP articles on elements, see e.g. iron. Double sharp (talk) 05:01, 21 September 2014 (UTC)
  • FN1: pages?
  • FN3: where does the page range end?
  • Some books include locations, others don't
  • Be consistent in how you format edition statements
  • GBooks links can be truncated
  • FN12: publisher?
  • FN15: textbook level and type is not part of the title
  • FN26:what is the purpose of the duplication here? Nikkimaria (talk) 02:10, 21 September 2014 (UTC)