Hydrogen astatide
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| Names | |
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| Systematic IUPAC name
Hydrogen astatide[1] | |
| 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 | |
| AtH | |
| Molar mass | 211 g·mol−1 |
| Related compounds | |
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 astatane, or astidohydrogen is a chemical compound with the chemical formula HAt, consisting of an astatine atom covalently bonded to a hydrogen atom.[2]
This chemical compound exhibits properties very similar to the other four hydrogen halides, and is in fact the strongest acid among them, however is limited in use since it will readily decompose into elemental hydrogen and astatine,[3] 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[4], 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. Further, a trend for hydrogen halides, or HX, is that enthalpy of formation lowers as the period increases for the halide. While 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; of which 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[5], as the astatine will decay into other elements.
References
- ^ "hydrogen astatide (CHEBI:30418)". Chemical Entities of Biological Interest (ChEBI). UK: European Bioinformatics Institute.
- ^ PubChem, "astatane - Compound Summary", accessed July 3, 2009.
- ^ Fairbrother, Peter, "Re: Is hydroastitic acid possible?", accessed July 3, 2009.
- ^ Advances in Inorganic Chemistry, Volume 6 by Emeleus, p.219, Academic Press, 1964 ISBN 0120236060
- ^ Gagnon, Steve, "It's Elemental", accessed July 3, 2009.
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