|Systematic IUPAC name
|Molar mass||1.01 g·mol−1|
|108.96 J K−1 mol−1|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
The hydrogen anion is a negative ion of hydrogen, H−. The hydrogen anion is an important constituent of the atmosphere of stars, such as the Sun. In chemistry, this ion is called hydride. The ion has two electrons bound by the electromagnetic force to a nucleus containing one proton.
The hydrogen anion is the dominant absorber of photons in the interstellar medium. It absorbs energies in the range 0.75–4.0 eV, which ranges from the infrared into the visible spectrum (Rau 1999, Srinivasan 1999). It also occurs in the Earth's ionosphere (Rau 1999).
Its existence was first proven theoretically by Hans Bethe in 1929 (Bethe 1929). H− is unusual because, in its free form, it has no bound excited states, as was finally proven in 1977 (Hill 1977). It has been studied experimentally using particle accelerators (Bryant 1977).
In chemistry, the hydride anion is hydrogen that has the oxidation state −1. Hydride compounds formally contain a hydrogen anion. Most such compounds are in fact rather covalent. An example of a hydride is borohydride (BH−
Sources and references
- Bethe, H. (1929). "Berechnung der Elektronenaffinität des Wasserstoffs". Zeitschrift für Physik (in German) 57 (11–12): 815–821. Bibcode:1929ZPhy...57..815B. doi:10.1007/BF01340659.
- Bryant, H. C.; Dieterle, B. D.; Donahue, J.; Sharifian, H.; Tootoonchi, H.; Wolfe, D. M.; Gram, P. A. M.; Yates-Williams, M. A. (1977). "Observation of Resonances near 11 eV in the Photodetachment Cross Section of the H− Ion". Physical Review Letters 38 (5): 228. Bibcode:1977PhRvL..38..228B. doi:10.1103/PhysRevLett.38.228.
- Hill, R. N. (1977). "Proof that the H− Ion Has Only One Bound State". Physical Review Letters 38 (12): 643. Bibcode:1977PhRvL..38..643H. doi:10.1103/PhysRevLett.38.643.
- Rau, A. R. P. (1996). "The Negative Ion of Hydrogen" (PDF). Journal of Astrophysics and Astronomy 17 (3): 113–145. doi:10.1007/BF02702300.
- Rau, A. (1999). The Negative Ion of Hydrogen.
- Srinivasan, G. (1999). "Chapter 5". From White Dwarfs to Black Holes: The Legacy of S. Chandrasekhar. Chicago: University of Chicago Press.
- "Hydride - PubChem Public Chemical Database". The PubChem Project. USA: National Center for Biotechnology Information.