page_title: Bismuth
section_title: Oxides and sulfides
hierarchical_section_title: Bismuth / Chemical compounds / Oxides and sulfides
caption_attribution_description: English: Crystal structure of matlockite (BiOCl). Colors: red - O, green - Cl, grey - Bi. (Z. Kristallogr.,1993,205, 35-40,Keramidas K.G., Voutsas G.P., Rentzeperis P.J.)
context_page_description: Bismuth is a chemical element with the symbol Bi and atomic number 83. It is a pentavalent post-transition metal and one of the pnictogens with chemical properties resembling its lighter group 15 siblings arsenic and antimony. Elemental bismuth may occur naturally, although its sulfide and oxide form important commercial ores. The free element is 86% as dense as lead. It is a brittle metal with a silvery white color when freshly produced, but surface oxidation can give it an iridescent tinge in numerous colours. Bismuth is the most naturally diamagnetic element, and has one of the lowest values of thermal conductivity among metals.
  Bismuth was long considered the element with the highest atomic mass that is stable, but in 2003 it was discovered to be extremely weakly radioactive: its only primordial isotope, bismuth-209, decays via alpha decay with a half-life more than a billion times the estimated age of the universe. Because of its tremendously long half-life, bismuth may still be considered stable for almost all purposes.
context_section_description: At elevated temperatures, the vapors of the metal combine rapidly with oxygen, forming the yellow trioxide, Bi
  ₂O
  ₃. When molten, at temperatures above 710 °C, this oxide corrodes any metal oxide, and even platinum. On reaction with base, it forms two series of oxyanions: BiO⁻
  ₂, which is polymeric and forms linear chains, and BiO³⁻
  ₃. The anion in Li
  ₃BiO
  ₃ is actually a cubic octameric anion, Bi
  ₈O²⁴⁻
  ₂₄, whereas the anion in Na
  ₃BiO
  ₃ is tetrameric.
  The dark red bismuth(V) oxide, Bi
  ₂O
  ₅, is unstable, liberating O
  ₂ gas upon heating. The compound NaBiO₃ is a strong oxidising agent.
  Bismuth sulfide, Bi
  ₂S
  ₃, occurs naturally in bismuth ores. It is also produced by the combination of molten bismuth and sulfur.
  Bismuth oxychloride (BiOCl, see figure at right) and bismuth oxynitrate (BiONO₃) stoichiometrically appear as simple anionic salts of the bismuthyl(III) cation (BiO⁺) which commonly occurs in aqueous bismuth compounds. However, in the case of BiOCl, the salt crystal forms in a structure of alternating plates of Bi, O, and Cl atoms, with each oxygen coordinating with four bismuth atoms in the adjacent plane. This mineral compound is used as a pigment and cosmetic (see below).
caption: Bismuth oxychloride (BiOCl) structure (mineral bismoclite). Bismuth atoms shown as grey, oxygen red, chlorine green.
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