Many of its chemical properties are similar to those of arsenic and antimony, although they are less toxic than derivatives of those lighter elements. Oxides and sulfides
At elevated temperatures, the vapors of the metal combine rapidly with oxygen, forming the yellow trioxide, Bi2O3. When molten, at temperatures above 710 °C, this oxide corrodes any metal oxide and even platinum. On reaction with a base, it forms two series of oxyanions: BiO−2, which is polymeric and forms linear chains, and BiO3−3. The anion in Li3BiO3 is a cubic octameric anion, Bi8O24−24, whereas the anion in Na3BiO3 is tetrameric.The dark red bismuth(V) oxide, Bi2O5, is unstable, liberating O2 gas upon heating. The compound NaBiO3 is a strong oxidising agent.Bismuth sulfide, Bi2S3, 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). Bismuthine and bismuthides
Unlike the lighter pnictogens nitrogen, phosphorus, and arsenic, but similar to antimony, bismuth does not form a stable hydride. Bismuth hydride, bismuthine (BiH3), is an endothermic compound that spontaneously decomposes at room temperature. It is stable only below −60 °C.
Bismuth subnitrate is a component of glazes that produces an iridescence and is used as a pigment in paint. Bismuth telluride is a semiconductor and an excellent thermoelectric material. Bi2Te3 diodes are used in mobile refrigerators, CPU coolers, and as detectors in infrared spectrophotometers. Bismuth oxide, in its delta form, is a solid electrolyte for oxygen. This form normally breaks down below a high-temperature threshold, but can be electrodeposited well below this temperature in a highly alkaline solution. Bismuth germanate is a scintillator, widely used in X-ray and gamma ray detectors. Bismuth vanadate is an opaque yellow pigment used by some artists oil, acrylic, and watercolor paint companies, primarily as a replacement for the more toxic cadmium sulfide yellows in the greenish-yellow (lemon) to orange-toned yellow range. It performs practically identically to the cadmium pigments, such as in terms of resistance to degradation from UV exposure, opacity, tinting strength, and lack of reactivity when mixed with other pigments. The most commonly-used variety by artists paint makers is lemon in color. In addition to being a replacement for several cadmium yellows, it also serves as a non-toxic visual replacement for the older chromate pigments made with zinc, lead, and strontium. If a green pigment and barium sulfate (for increased transparency) are added it can also serve as a replacement for barium chromate, which possesses a more greenish cast than the others.