|Molar mass||211.00 g·mol−1|
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
|what is: / ?)(|
Hydrogen astatide, also known as astatine hydride, astatane, or astidohydrogen, is a chemical compound with the chemical formula HAt, consisting of an astatine atom covalently bonded to a hydrogen atom.
This chemical compound exhibits properties very similar to the other four hydrogen halides, and is in fact the strongest acid among them; however, it is limited in use due to its ready decomposition into elemental hydrogen and astatine, 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, 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. 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; 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, as the astatine will quickly decay into other elements.
- PubChem, "astatane - Compound Summary", accessed July 3, 2009.
- Fairbrother, Peter, "Re: Is hydroastatic acid possible?", 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.
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