Bismuth (Bi)
Bismuth (Bi) is a rare metallic element with the atomic number 83, belonging to the nitrogen group of the periodic table. It is comparable in abundance to silver in the Earth's crust and is one of the few metals found in nature in its elemental form. Bismuth is typically found in conjunction with lead, zinc, or tin deposits, particularly in regions such as Bolivia, Canada, and Germany, and is extracted mainly as a by-product of refining copper, lead, and zinc.
Bismuth has unique physical properties; it is brittle, has a white appearance with a pink hue, and expands upon solidifying, which is rare for metals. Its primary applications include use as an alloying agent in various metallurgical contexts, particularly in low-melting fusible alloys. Additionally, bismuth compounds serve important roles in the pharmaceutical industry, notably in treating digestive issues and as an antisyphilitic agent. Despite its heavy metal classification, bismuth is relatively non-toxic in its elemental form, contrasting with the high toxicity of many of its inorganic compounds. With an annual production of around 6,000 metric tons, bismuth's rarity contributes to its limited environmental impact and ongoing interest in its commercial and industrial applications.
Bismuth (Bi)
Where Found
Bismuth is a rare element in the Earth’s crust, with an abundance roughly equal to that of silver. It is also one of the few metallic elements that can be found in nature in its elemental form. As such it is often found in the same areas as lead, zinc, or tin deposits in locations such as Bolivia, Canada, and Germany. In addition, it occurs in ores as an oxide, sulfide, or carbonate. Rather than being mined and refined directly, bismuth is obtained commercially as a by-product of copper, lead, and zinc refining operations. Leading producers are China, Mexico, and Belgium.
Primary Uses
Bismuth and its compounds are used in pharmaceutical applications as well as in several commercial chemical syntheses. By far the main commercial use of bismuth is as an alloying agent.
Technical Definition
Bismuth (atomic symbol Bi) has an atomic number of 83 and is found in the nitrogen group (main Group V) of the periodic table. It is similar to antimony in its chemical properties but has significantly greater metallic behavior than the other elements in the group. There is only one naturally occurring isotope, so the atomic weight of bismuth, 208.980, is known very precisely. The element is brittle and white in appearance, with a pink tinge. It occurs in a variety of crystalline structures. The metal has a high resistivity and melts at 271.4° Celsius with a boiling point of 1,564° Celsius. Bismuth is unusual in that its volume expands by about 3 percent when it solidifies from the liquid. The solid has a density of 9.9 grams per cubic centimeter.
Description, Distribution, and Forms
With a rarity akin to that of silver, bismuth is a relatively minor component of the Earth’s crust. It possesses some unique credentials: For example, all elements with an atomic number higher than bismuth are radioactive. It is one of three elements that is less dense in the solid phase than in the liquid. It is also one of only a handful of metals that can be found in nature in their elemental, or native, form. Elemental bismuth is not particularly toxic, an unusual property in heavy metals. However, inorganic bismuth compounds are often extremely poisonous. The relative rarity of bismuth has minimized its environmental impact.
History
The earliest recorded use of bismuth was in the mid-1400’s as an alloying material in casting type. German scientist Georgius Agricola stated that bismuth was a metal in the same family of metals as tin and lead. In 1753, French chemist Claude François Geoffroy identified bismuth as a chemical element, confirming Agricola’s postulation.
Obtaining Bismuth
In addition to the native state, bismuth occurs in ores as an oxide, sulfide, and carbonate. Because of the scarcity of bismuth ores in the Earth’s crust, it is not mined directly but is typically produced commercially by extracting and refining it from the anode sludge generated during the electrochemical production of other metals. Annual world production of bismuth is on the order of 6,000 metric tons.
Uses of Bismuth
Functioning as a metallurgical additive remains one of the major uses of bismuth. In particular, fusible alloys, which have low melting points and are particularly useful in fire detection, often incorporate bismuth. The other major use of bismuth is in the pharmaceutical industry, where it is used to treat indigestion and as an antisyphilitic agent.
Bibliography
Natural Resources Canada.
U.S. Geological Survey.