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| Names | |||
|---|---|---|---|
| IUPAC name
Hydrogen astatide[1]
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| Systematic IUPAC name
Astatane[2] | |||
| Identifiers | |||
3D model (JSmol)
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| ChEBI | |||
| ChemSpider | |||
| 532398 | |||
PubChem CID
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CompTox Dashboard (EPA)
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| Properties | |||
| HAt | |||
| Molar mass | 211 g·mol−1 | ||
| Boiling point | −3 °C (27 °F; 270 K) estimated[3] | ||
| Soluble | |||
| Conjugate acid | Astatonium | ||
| Conjugate base | Astatide | ||
| Related compounds | |||
Other anions
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Hydrogen bromide | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Hydrogen astatide, also known as astatine hydride, astatane, astatidohydrogen or hydroastatic acid, is a chemical compound with the chemical formula HAt, consisting of an astatine atom covalently bonded to a hydrogen atom.[4] It thus is a hydrogen halide.
This chemical compound can dissolve in water to form hydroastatic acid, which exhibits properties very similar to the other five binary acids, and is in fact the strongest among them. However, it is limited in use due to its ready decomposition into elemental hydrogen and astatine,[5] as well as the short half-life of the various isotopes of astatine. Because the atoms have a nearly equal electronegativity, and as the At+ ion has been observed,[6] dissociation could easily result in the hydrogen carrying the negative charge. Thus, a hydrogen astatide sample can undergo the following reaction:
- 2 HAt → H+ + At− + H− + At+ → H2 + At2
This results in elemental hydrogen gas and astatine precipitate. Furthermore, a trend for hydrogen halides, or HX, is that enthalpy of formation becomes less negative, i.e., decreases in magnitude but increases in absolute terms, as the halide becomes larger. Whereas hydroiodic acid solutions are stable, the hydronium-astatide solution is clearly less stable than the water-hydrogen-astatine system. Finally, radiolysis from astatine nuclei could sever the H–At bonds.
Additionally, astatine has no stable isotopes. The most stable is astatine-210, which has a half-life of approximately 8.1 hours, making its chemical compounds especially difficult to work with,[7] as the astatine will quickly decay into other elements.
YouTube Encyclopedic
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Reacting Fluorine with Caesium - First Time on Camera
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Transcription
So I've come up to the University of Leicester, and I've brought with me a tube here containing Caesium. Caesium is found in the far corner here. And it is the most reactive metal in the entire periodic table, even more reactive than Francium. This is a radioactive element and it decays. But actually, Caesium is more reactive than this. It's the most reactive thing we can find. Now, why have I come up to Leicester? I brought this because I want to see how it reacts with the most reactive, non-metal in the entire periodic table. And that's the element Fluorine. And we don't think this has ever been shown before, so we're not entirely sure how it's going to go. So I'm gonna go and see. Having decided that I wanted to do this crazy reaction, I needed to find just the right person to handle the Fluorine. And this is Professor Eric Hope here from the University of Leicester. So, thank you very much for helping me out with this. You're welcome. And what was your first reaction, by the way, when I said I want to try Caesium with Fluorine? I thought you were totally and utterly mad. Uh huh. That's probably most people's reaction. Now we've designed this apparatus with quite a lot of thought. One of the problems here is that we want to do this at the Ri. And transporting Fluorine is a little bit tricky, is it? Certainly. It reacts vigorously, as we will see, with virtually any element in the periodic table. Eric's come up with this fantastic idea of just filling the coils in the apparatus, this plastic tubing that has been sensitised to fluorine so it's not going to react with it. Basically, what we have in here is Fluorine, but at the same pressures there is in the atmosphere around it that nothing's going to leak in, nothing's going to leak out. So even if there was a major event, then the Fluorine would not be released from the apparatus. To show the extreme reactivity of Fluorine, we're going to set fire to something. We all know how hard it is to start a barbecue using this stuff, this is charcoal, trying to get it to burn with the Oxygen from the air. I'd be easy, though, if the atmosphere contained Fluorine. Is this your one or is this my one? No that was yours, I think. OK, was it? No. You see. OK, should we see the reaction then? Let's have a go. Wow. This demonstrates the extreme reactivity of Fluorine gas. This was a tiny quantity of Fluorine being played onto the surface of the charcoal there. And as soon as the two came into contact, there was this very violent reaction, generated a lot of heat, as you saw the flames there. But the charcoal isn't terribly reactive. Caesium is much more reactive. So I think we should try this reaction now then. This is my Caesium. Have you seen Caesium before? No. There's quite a lot of it, isn't there? Quite beautiful. Beautiful, yes. And so dangerous. So this is a combination between the two most reactive elements in the periodic table. We've got Fluorine, the most reactive non-metal, and Caesium, the most reactive metal. Let's push them through again. Yep. Yeah, it looks good. All right, we are nearly ready. I'll lower this. Yep, and I'll turn. You look after your pipes. Incredibly beautiful reaction there between Caesium and Fluorine. This intense light. And I don't think many people have seen that before.
Preparation
Hydrogen astatide can be produced by reacting astatine with hydrocarbons (such as ethane):[8]
- C2H6 + At2 → C2H5At + HAt
This reaction also produces the corresponding alkyl astatide, in this case ethyl astatide (astatoethane).
References
- ^ "Hydrogen astatide (CHEBI:30418)".
- ^ Henri A. Favre; Warren H. Powell, eds. (2014). Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013. Cambridge: The Royal Society of Chemistry. p. 131.
- ^ Analytical Chemistry of Technetium, Promethium, Astatine and Francium by Avgusta Konstantinovna. Lavrukhina, Aleksandr Aleksandrovich Pozdnyakov ISBN 0250399237
- ^ PubChem, "astatane - Compound Summary", accessed July 3, 2009.
- ^ Fairbrother, Peter, "Re: Is hydroastatic acid possible?" Archived 2011-02-02 at the Wayback Machine, accessed July 3, 2009.
- ^ Advances in Inorganic Chemistry, Volume 6 by Emeleus, p.219, Academic Press, 1964 ISBN 0-12-023606-0
- ^ Gagnon, Steve, "It's Elemental", accessed July 3, 2009.
- ^ Hagen, A. P. (1989). The formation of bonds to halogens. New York: VCH Publishers. ISBN 978-0-470-14538-8. OCLC 472256324.
This page was last edited on 9 January 2024, at 01:52