dianion
Sign in to saveAlso known as divalent anion, divalent negative ion
A dianion is an anion with a net charge of −2. While there exist many stable molecular dianions, such as Tetrafluoroberyllate| and , thus far no stable atomic dianion has been found: Electron shielding and other quantum mechanical effects tend to make the addition of another electron to an atomic anion unstable.
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A dianion is an anion with a net charge of −2. While there exist many stable molecular dianions, such as {{chem2|BeF_{4}^{2-} }} and {{chem2|MgF_{4}^{2-} }}, thus far no stable atomic dianion has been found: Electron shielding and other quantum mechanical effects tend to make the addition of another electron to an atomic anion unstable.
The most heavily studied atomic dianion is H, usually as a short-lived resonance between an electron and a hydrogen ion. In 1976, its half-life was experimentally measured to be 23 ± 4 nanoseconds.