An angstrom, angström, or ångström (symbol Å) is a unit of length. It is not an SI unit. It is accepted (although discouraged) for use with the SI. It is sometimes used expressing the size of atoms, and lengths of chemical bonds and visible-light spectra.

Definition

1 ångström (Å) = 10^–10 metres = 0.1 nm = 100 pm

For an example of lengths in this unit, the average diameter of an atom, calculated from its empirical radius, ranges from approximately 0.5 Å for hydrogen (the smallest element) to 3.8 Å for uranium (the largest naturally occurring elements on Earth).

Origin

The ångström is named after the Swedish physicist Anders Jonas Ångström (1814–1874), one of the founders of spectroscopy. Besides astrophysics, Ångström was also a student of heat transfer, terrestrial magnetism, and the aurora borealis, which was so prominent for him in his northern skies. He created a spectrum chart of solar radiation that expresses the length of electromagnetic radiation in the electromagnetic spectrum on the order of multiples of one ten-millionth of a millimeter, or 1 meters. This unit of length became known as the ångström, Å.

Representation in Unicode

Unicode includes the "angstrom sign" at U+212B (which looks like Å in a web browser). However, the "angstrom sign" is canonically decomposed into U+00C5 (Å), thereby seen as a (preexisting) encoding mistake, and it is better to use U+00C5 (Å) directly.

See also

• Conversion of units
• 1 E-10 m

Units of length

Ångstrom | Angström | Ангстрьом | Àngstrom | Ångstrøm | Ångström (Einheit) | Ongström | Angstrom | Angstromo (unuo) | Angstrom | آنگستروم | Angström | Angstrom | 옹스트롬 | Ångstrom | Angstrom | Angstrom | אנגסטרם | Ångström | オングストローム | Ångstrøm | Angstrem | Ångström | Ангстрем | Angström | Ångström | Ångström | Ångström | อังสตรอม | Ångström | Angström | Ангстрем | 埃格斯特朗 (单位)