Hydrogen astatide

Hydrogen astatide

Names
Systematic IUPAC name Hydrogen astatide
Identifiers
3D model (JSmol)	Interactive image
ChEBI	CHEBI:30418
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
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 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 is limited in use since it will readily decompose 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 decay into other elements.