page_title: Angstrom
hierarchical_section_title: Angstrom
caption_attribution_description: English: Anders Jonas Ångström
context_page_description: The angstrom or ångström is a metric unit of length equal to 10⁻¹⁰ m; that is, one ten-billionth of a metre, 0.1 nanometre, or 100 picometres. Its symbol is Å, a letter of the Swedish alphabet.
  The ångström is not a part of the SI system of units, but it can be considered part of the metric system in general. Although deprecated by both the International Bureau of Weights and Measures and the US National Institute of Standards and Technology, the unit is still often used in the natural sciences and technology to express sizes of atoms, molecules, microscopic biological structures, and lengths of chemical bonds, arrangement of atoms in crystals, wavelengths of electromagnetic radiation, and dimensions of integrated circuit parts. The atomic radii of phosphorus, sulfur, and chlorine are about 1 ångström, while that of hydrogen is about 0.5 ångströms. Visible light has wavelengths in the range of 4000–7000 Å.
  The unit is named after 19th-century Swedish physicist Anders Jonas Ångström. The BIPM and NIST use the spelling ångström, including Swedish letters; but this form is rare in English texts. Some popular US dictionaries list only the spelling angstrom.
context_section_description: The angstrom (/ˈæŋstrəm/, /ˈæŋstrʌm/; ANG-strəm, ANG-strum) or ångström is a metric unit of length equal to 10⁻¹⁰ m; that is, one ten-billionth of a metre, 0.1 nanometre, or 100 picometres. Its symbol is Å, a letter of the Swedish alphabet.
  The ångström is not a part of the SI system of units, but it can be considered part of the metric system in general. Although deprecated by both the International Bureau of Weights and Measures (BIPM) and the US National Institute of Standards and Technology (NIST), the unit is still often used in the natural sciences and technology to express sizes of atoms, molecules, microscopic biological structures, and lengths of chemical bonds, arrangement of atoms in crystals, wavelengths of electromagnetic radiation, and dimensions of integrated circuit parts. The atomic (covalent) radii of phosphorus, sulfur, and chlorine are about 1 ångström, while that of hydrogen is about 0.5 ångströms. Visible light has wavelengths in the range of 4000–7000 Å.
  The unit is named after 19th-century Swedish physicist Anders Jonas Ångström (Swedish: [ˈɔ̂ŋːstrœm]). The BIPM and NIST use the spelling ångström, including Swedish letters; but this form is rare in English texts. Some popular US dictionaries list only the spelling angstrom. The symbol should always be "Å", no matter how the unit is spelled. Nonetheless, "A" is often used in less formal contexts or typographically limited media.
caption: Anders Jonas Ångström, after whom the unit was named.
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