Hydrogen astatide

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Hydrogen astatide

Ball-and-stick model of hydrogen astatide Spacefill model of hydrogen astatide
Identifiers
3D model (JSmol)	Interactive image
ChEBI	CHEBI:30418 Y
ChemSpider	22432 Y
Gmelin Reference	532398
PubChem CID	23996
CompTox Dashboard (EPA)	DTXSID10274755
InChI InChI=1S/AtH/h1H Y Key: PGLQOBBPBPTBQS-UHFFFAOYSA-N Y InChI=1/AtH/h1H Key: PGLQOBBPBPTBQS-UHFFFAOYAG
SMILES [AtH]
Properties
Chemical formula	AtH
Molar mass	211 g·mol−1
Related compounds
Other anions	Hydrogen bromide Hydrogen chloride Hydrogen fluoride Hydrogen iodide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

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. 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, as the astatine will quickly decay into other elements.