Talk:Thorium

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• Masterton, W. L.; Hurley, C. N.; Neth, E. J. Chemistry: Principles and reactions (7th ed.) has no date.
• van Spronsen, J. W. (1969). The periodic system of chemical elements. Pub. too early for ISBN; Missing OCLC;
• Feynman, R.; Leighton, R.; Sands, M. (1963). The Feynman Lectures on Physics. Pub. too early for ISBN; Missing OCLC;
• Educational Foundation for Nuclear Science, Inc. Bulletin of the Atomic Scientists. pp. 19–20. ISSN 0096-3402. Missing Publisher; Missing Year/Date;
• Hyde, E. K. (1960). The radiochemistry of thorium (PDF). National Academy of Sciences. Retrieved 29 September 2017. Missing OCLC;
• Clayton, D. D. (1968). Principles of Stellar Evolution and Nucleosynthesis. McGraw-Hill Education. pp. 577–591. ISBN 978-0-226-10953-4. Pub. too early for ISBN; Missing OCLC;
• Thomson, T. (1831). A System of Chemistry of Inorganic Bodies. 1. Baldwin & Cradock and William Blackwood. p. 475. Missing OCLC;
• Dana, J. D.; Brush, G. J. (1875). A System of Mineralogy: Descriptive Mineralogy, Comprising the Most Recent Discoveries. John Wiley & Sons. p. 529. Missing OCLC;
• Selbekk, R. S. (2007). "Morten Thrane Esmark". Store norske leksikon (in Norwegian). Kunnskapsforlaget. Retrieved 16 May 2009. Missing ISBN;
• Inconsistent use of access dates and archiving on web pages.
• Some books cited repeatedly but not moved into Bibliography section, e.g. Fontani, M.; Costa, M.; Orna, V. (2014). The Lost Elements: The Periodic Table's Shadow Side. Oxford University Press. p. 73.
• ASIN uses ISBN for Langford, R. E. (2004). Introduction to Weapons of Mass Destruction: Radiological, Chemical, and Biological.
• Thanks Lingzhi ♦ (talk) 15:18, 30 January 2018 (UTC)

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[The metal] does not readily dissolve in most common acids, with the exception of hydrochloric acid, where it dissolves leaving a black insoluble residue of ThO(OH,Cl)H

This sentence does not make sense. Either it dissolves

Th +4H⁺ → Th⁴⁺ + 2H₂↑

or it does not. If it dissolves, the oxide layer on the metal surface will also dissolve in the acidic solution.

ThO₂ + 4H⁺ → Th⁴⁺ + 4H₂O

When alkali is added to an acidic (HCl) solution of Th(IV), [Th(OH)]³⁺ is first formed (pK≈9), then precipitation occurs. It is most unlikely that the precipitate is an insoluble /basic hydroxide /oxide /chloride /hydride species, as metal hydrides are not produced under these conditions. Petergans (talk) 11:10, 5 March 2018 (UTC)

I think this sentence can actually counted as supported by a source. Here's what the source says:

Thorium reacts vigorously with hydrochloric acid. The reaction with hydrochloric acid always leaves a certain amount of a black residue (12 to 15%) behind, which was first thought to be ThO2 that was originally present in the metal (Matignon and Delepine, 1901; Meyer, 1908; von Wartenberg, 1909). As discussed in Section 3.7.3, other studies have suggested that a lower‐valent thorium oxide hydrate, ThO·H2O, is formed but it is much more likely that this compound is in fact an oxide hydride containing hydroxide and chloride ions according to ThO(X)H (X -- combination of OH− and Cl−) (von Bolton, 1908; Karstens, 1909, Katzin, 1944,1958; Karabash, 1958; Katzin et al., 1962). This assumption is also supported by mass spectroscopic investigations that show Cl− to be present in the residue(Ackermann and Rauh, 1973a). The reaction of thorium with other acids occurs slowly, with nitric acid even passivation is observed (Smithells, 1922; Schuleret al., 1952).

Given this, I don't think we're particularly wrong here, are we?--R8R (talk) 11:54, 5 March 2018 (UTC)

Under Isotopes, I found a slight error; ²³⁴U is the parent of ²³⁰Th, not ²³⁸U.

DaveyHume (talk) 02:17, 14 May 2019 (UTC)

@DaveyHume: It's not an error. The important thing is that ²³⁰Th occurs in the decay chain of ²³⁸U (and the term "daughter" can refer to the whole decay chain as it does here), because that is one of the two primordial U isotopes in nature. ²³⁴U is not important here as it only occurs in secular equilibrium with its much longer-lived progenitor, just like ²³⁰Th does. Double sharp (talk) 04:33, 14 May 2019 (UTC)

Supported: 'Daughter' is indeed a term for elements in the decay chain. I made a very small addition that Thorium also have been used in some broadcast radio tubes. And very nearly added the fact that such tubes seem to have turned up in Chinese built audiophile amplifiers. But I caught myself on the latter matter, if someone feel that piece of information to be relevant you might double check on https://en.wikipedia.org/wiki/845_(vacuum_tube) that this information is correct plus any online ad for YAQIN MS-650B Tube Amplifier which show that the tube using Thorium might be in current use. — Preceding unsigned comment added by 94.255.128.46 (talk) 19:57, 13 February 2020 (UTC)

I did recently find this about the reaction of uranium with water (thorium should be similar). Apparently some hydride formation takes place because the H₂ liberated by the reaction with water then directly reacts with the uranium metal. Double sharp (talk) 08:57, 18 March 2021 (UTC)

Incandescent ThO₂

@Double sharp: if you insist on this dubious blue light, then add more sources explicating specific conditions where may it be a kind of blue. We are, hopefully, not fools to expect a bluish thermal radiation at some 3660 K. Incnis Mrsi (talk) 14:02, 8 July 2019 (UTC)

The source does not state any conditions needed for this effect. The paper we cite in the article on candoluminescence (which explains why ThO₂ does this; it's ref 132) writes the following: 'Gases in a flame have a high content of free radicals which can release large amounts of energy upon recombination or de-excitation. Materials vary in ability to promote recombination of radicals and one with a high recombination coefficient, other conditions being equal, will attain a higher temperature. ThO₂ : Ce is one such catalyst and recombination effects account in part for its high visible emission in the "high-temperature candoluminescence" region'. This seems to be borne out from work as early as 1901, as the article also states that 'Bunte [12, 36] in 1901 found that a hot Welsbach mantle could be kept at “full glow” by exposure to a cold unignited gas--air mixture and concluded that catalytic recombination was an important factor. Bunte also showed that the temperature at which hydrogen and oxygen combine was lowered in the presence of CeO₂'. So it seems plausible that for thoria exceptionally candoluminescence can be seen without much sensitivity to conditions because of its catalytic effect. I have added some sentences to the article based on the summary in this source. Double sharp (talk) 14:28, 8 July 2019 (UTC)

Again. “When heated” doesn’t explain why presumed “free radicals that appear in high concentration in a flame” are present. Surely does heating ThO₂ in the air produce a kind of flame? The reader has to do guesswork after Double sharp. Incnis Mrsi (talk) 17:28, 8 July 2019 (UTC)

No, the reader has to do guesswork after reading the sources, who give no conditions. The original Wickleder et al. source I used for this statement said only "Lastly, thorium oxide, when heated, produces an intense blue light and mixed with ceria at 1%, produces a more intense white light. It is this property that was the basis for the thoriated gas mantle industry.", as I quoted in my edit summary. I can hardly put in here what they do not write either, especially since as noted above a flame does not seem to be necessary for the effect to be seen with ThO₂ + CeO₂. Double sharp (talk) 04:16, 9 July 2019 (UTC)

Wickleder et al. are authors for an obscure journal, not for an encyclopedia. Well, (almost) all are volunteers here, but undoing my removal of “blue” creates a WP:BURDEN. Incnis Mrsi (talk) 08:38, 9 July 2019 (UTC)

@Incnis Mrsi: The Wickleder et al. chapter is from a very well-known text on the actinides and transactinides (The Chemistry of the Actinide and Transactinide Elements, whose first edition had Seaborg himself as a coauthor), so not quite an obscure journal. As WP:BURDEN expressly notes: "it is satisfied by providing an inline citation to a reliable source that directly supports the contribution." Considering the quote above on "intense blue light", this has been done. I would of course like to have more detail but I have not yet found any sources that actually give it (though of course I will be continuing to look).

Pinging R8R as well, who collaborated with me on this article. Double sharp (talk) 16:01, 9 July 2019 (UTC)

In general, I think Double sharp has it right. Here's a credible source, it says this, we follow, you can't expect us to do more if we ourselves can't attribute this thought to someone. My understanding is that "free radicals in high concentration" is the needed but sufficient explanation to give the general idea but stay focused on the topic at hand. This is an article on thorium, after all. For similar reasons, we don't need to explain in each article on an element why it passes the flame test the way it does. We could, but not exactly should.--R8R (talk) 10:55, 13 July 2019 (UTC)

Use in cavity magnetrons filaments (used in microwave ovens)

The page on cavity magnetrons states Thorium is used in the filaments of the magnetron. It would be interesting to find references to support this and to mention it under the applications for / uses of Thorium.