Term: Bohr radius
https://doi.org/10.1351/goldbook.B00693

Definition:
Atomic fundamental physical constant used as atomic unit of length: \[a_{0}=\frac{4\ \pi \ \varepsilon_{0}\ \mathrm{\hslash }^{2}}{m_{\text{e}}\ e^{2}}=5.291 \ 772\ 49\ (24)\times 10^{-11}\ \text{m}\] where e is the elementary charge, ℏ is the Planck constant divided by 2π and m e is the electron rest mass.

Related Terms:
1) elementary charge (http://doi.org/10.1351/goldbook.E02032).
2) planck constant (http://doi.org/10.1351/goldbook.P04685).
3) electron rest mass (http://doi.org/10.1351/goldbook.E02008).
4) atomic unit (http://doi.org/10.1351/goldbook.A00504).

Source: CODATA Bull. 1986, 63, 1 (https://doi.org/10.6028/jres.092.010)

Citation: 'Bohr radius' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.B00693

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