Hydrogen anion

<p>The hydrogen anion, H−, is a <a href="/facts/Electric_charge/xxsBfmlB">negative</a> <a href="/facts/Ion/3bePpDna">ion</a> of hydrogen, that is, a <a href="/facts/Hydrogen_atom/ncVpPbuE">hydrogen atom</a> that has captured an extra electron. The hydrogen anion is an important constituent of the atmosphere of <a href="/facts/Star/PFbd6ICx">stars</a>, such as the <a href="/facts/Sun/CadPCVHh">Sun</a>.  In chemistry, this ion is called hydride. The ion has <a href="/facts/Two-electron_atom/Y5bvcgzb">two electrons</a> bound by the <a href="/facts/Electromagnetic_force/oAkmALHT">electromagnetic force</a> to a nucleus containing one proton.
</p><p>The binding energy of H− equals the binding energy of an extra electron to a hydrogen atom, called <a href="/facts/Electron_affinity/1mf4A396">electron affinity</a> of hydrogen. It is measured to be 0.754195(19) <a href="/facts/Electronvolt/YMT1fqX9">eV</a> or 0.02771616(70) <a href="/facts/Hartree/gL7IDopu">hartree</a> (see <a href="/facts/Electron_affinity_(data_page)/1najm13F">Electron affinity (data page)</a>). The total ground state energy thus becomes −14.359888 eV.
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Hydrogen anion open-in-new

Hydrogen anion