DESCRIPTION
Its symbol is Bi, it is a scarce metallic chemical element, pinkish in color. Its atomic number Z is 83 and it is in group 15 of the periodic system. It occupies the 73rd place in abundance among the elements of the earth’s crust, it represents 8.5×10-7 % of the weight of the crust and is as scarce as silver. The main deposits are in South America, it is normally obtained as a by-product of the refining of Copper and Lead concentrates.
PROPERTIES
Bismuth is a grayish-white, crystalline, lustrous, hard and brittle metal. It is one of the few metals that expand when solidified. Its thermal conductivity is lower than that of any other metal except mercury. Bismuth is inert in dry air at room temperature, but oxidizes slightly when wet. It rapidly forms an oxide film at temperatures above its melting point, and ignites on reaching red forming the yellow oxide, Bi2O3. The metal combines directly with halogens and with sulfur, selenium and tellurium, but not with nitrogen or phosphorus.
In almost all bismuth compounds it is in trivalent form. However, it can sometimes be pentavalent. Sodium bismuthate and bismuth pentafluoride are perhaps the most important Bi(V) compounds. The former is a powerful oxidizing agent and the latter a useful fluorinating agent for organic compounds.
Bismuth metal is neither classified as a hazardous substance by the EU nor as dangerous goods for transport.
APPLICATIONS
- Low melting point alloys.
- Lead substitute in copper alloys for water pipelines.
- Special welds.
- Bleaching effect in foundries.
- Pharmaceutical applications.
