BISMUTH (REVISED)

Note: This article, originally published in 1998, was updated in 2006 for the eBook edition.

Overview

Early chemists had difficulty separating similar elements from each other. Elements with similar properties can only be told apart with tests not available before the eighteenth century.

Chemists also believed that metals grew in the earth, in much the same way that plants grow. Unattractive metals, like lead, were thought to be young or immature metals. More attractive metals, like tin, were thought to be partially grown. The most mature metals were silver and gold. This made identification very difficult. Were chemists looking at "older lead" or a "younger tin?"

Bismuth is one of the elements often confused with other elements. Old manuscripts show that bismuth was often confused with lead, tin, antimony, or even silver.

SYMBOL
Bi

ATOMIC NUMBER
83

ATOMIC MASS
208.9804

FAMILY
Group 15 (VA)
Nitrogen

PRONUNCIATION
BIZ-muth

Bismuth was used in early alloys. An alloy is made by melting and mixing two or more metals. The mixture has properties different from those of the individual metals. The first printing presses (dating back to the 1450s) held type made of bismuth alloys.

Discovery and naming

As with arsenic and antimony, it is difficult to say who exactly discovered bismuth. The name bismuth was probably taken from two German words, weisse masse, meaning "white mass." The phrase describes how the element appears in nature. Later the name was shortened to wismuth, and then to bisemutum, before bismuth came into common use.

In 1753, French scholar Claude-Françoise Geoffrey wrote a book summarizing everything that was known about bismuth at the time.

Physical properties

Bismuth is a soft, silvery metal with a bright, shiny surface and a yellowish or pinkish tinge. The metal breaks easily and cannot be fabricated (worked with) at room temperature. Its melting point is 271°C (520°F) and its boiling point is 1,560°C (2,480°F). Its density is 9.78 grams per cubic centimeter.

Bismuth expands as it solidifies (changes from a liquid to a solid). Most materials contract (have a smaller volume) as they solidify. Few elements behave like bismuth.

This property makes bismuth useful for producing type metal. An alloy of bismuth is melted and poured into molds that have the shape of letters and numbers. As the type cools, it solidifies and expands to fill all the comers of the mold. The type formed is clear, crisp, and easy to read. Computer typesetting, however, has largely replaced bismuth metal typesetting.

Chemical properties

Bismuth combines slowly with oxygen at room temperature. Bismuth oxide (Bi₂O₃) gives the metal its pinkish or yellowish tinge. At higher temperatures, the metal burns to form bismuth oxide. Bismuth also reacts with most acids.

Occurrence in nature

The abundance of bismuth in the Earth's crust is estimated to be about 0.2 parts per million, making it a relatively rare element. This puts it in the bottom quarter of the elements according to their abundance in the earth.

Bismuth is seldom found in its elemental state (as a pure metal) in the earth. Its compounds are generally found along with ores of other metals, such as lead, silver, gold, and cobalt. The most important mineral of bismuth is bismuthinite, also known as bismuth glance (Bi₂S₃).

The largest producers of bismuth in the world are Mexico, Peru, China, Belgium, and Japan. Bismuth is produced in the United States only as a by-product of lead refining in Nebraska.

Isotopes

There is only one naturally occurring isotope of bismuth, bismuth-209. Isotopes are two or more forms of an element. Isotopes differ from each other according to their mass number. The number written to the right of the element's name is the mass number. The mass number represents the number of protons plus neutrons in the nucleus of an atom of the element. The number of protons determines the element, but the number of neutrons in the atom of any one element can vary. Each variation is an isotope.

A number of radioactive isotopes of bismuth are known also. A radioactive isotope is one that breaks apart and gives off some form of radiation. Radioactive isotopes are produced when very small particles are fired at atoms. These particles stick in the atoms and make them radioactive.

None of the radioactive isotopes of bismuth have any commercial applications.

Extraction

Bismuth metal is usually separated from ores of other metals by the Betterton-Kroll process. Calcium or magnesium is added to the molten (melted) ore where it forms an alloy with bismuth. Later, the bismuth can be separated from the calcium or magnesium to make the pure metal.

The name bismuth was probably taken from two German words, weisse masse, meaning "white mass."

Uses

The primary use of bismuth metal is in making alloys. Many bismuth alloys have low melting points. The metal itself melts at 271°C, but some bismuth alloys melt at temperatures as low as 70°C (158°F). This temperature is below the boiling point of water. These alloys are used in fire sprinkler systems, fuel tank safety plugs, solders, and other applications.

There is increasing interest in using bismuth as a substitute for Lead in alloys. Lead is toxic to humans and animals so scientists are trying to find ways to replace lead in most applications. For example, an alloy containing 97 percent bismuth and 3 percent tin is popular as shot used in waterfowl hunting. Bismuth is also being used in place of lead in plumbing applications and in coloring paints, ceramics, and glazes.

Compounds

Two-thirds of bismuth produced in the United States is made into drugs, pharmaceuticals, and other chemicals. The most widely used compound is bismuth subsalicylate (Bi(C₇H₅O₃)₃), the active ingredient in many over-the-counter stomach remedies. An over-the-counter drug is one that can be sold without a prescription.

A recently released bismuth compound is used to treat ulcers, a common stomach problem.

Other compounds used in medicine include bismuth ammonium citrate (Bi(NH₄)₃(C₆H₅O₇)₂), bismuth citrate (BiC₆H₅O₇)₂), bismuth subgallate (Bi(OH)₂OOCC₆H₂(OH)₃), and bismuth tannate. These compounds are used to treat a large variety of problems, including burns, stomach ulcers, intestinal disorders, and in veterinary applications.

Bismuth compounds are also widely used in cosmetics. Bismuth oxychloride (BiOCl) is a lustrous white powder added to face powder. Bismuth subcarbonate [(BiO)₂CO₃] and bismuth subnitrate [4BiNO₃(OH)₂ • BiO(OH)] are also white powders used to give a pearl-like luster to lipstick, eyeshadow, and other cosmetics.

There is increasing interest in using bismuth as a substitute for lead in alloys. Lead is toxic to humans and animals.

Health effects

Bismuth and its compounds are not thought to be health hazards. In fact, bismuth compounds are used in medications. A recently released bismuth compound is used to treat ulcers, a common stomach problem.

Bismuth

melting point: 271.4°C
boiling point: 1,564 ± 5°C
density: 9.747 g/cm³
most common ions: Bi³⁺, Bi⁴⁺

Bismuth is a brittle, crystalline metal that is white with a pinkish tint. It is the heaviest and only nontoxic member of the heavy metals . Its name is derived from the German Wismut ("white metal"), which was Latinized to bisemutum by G. Bauer in 1530. In early years it was confused with tin and lead. Bismuth has only one naturally occurring isotope , ²⁰⁹Bi (the heaviest stable isotope of any element).

Peru, Japan, Mexico, and Canada are the main producers of bismuth. It can be found in several ores: bismuthinite (Bi₂S₃), bismite (Bi₂O₃), and bismutite (BiO₂)CO₃. It is also obtained as a by-product of the refining of silver and gold ores in the United States. Bismuth has an abundance in Earth's crust of 0.008 parts per million.

Bismuth commonly forms cations of +3 charge. It forms the basic oxide Bi₂O₃ and salts of oxoacids such as Bi₂(SO₄)₃ and Bi(NO₃)₃. Reaction of the metal with halides such as fluorine and chlorine results in a salt with the formula of BiX₃. Because of the size of the metal atom, the linkages are more ionic than those found for other group members.

Bismuth is the most diamagnetic of all metals and has low thermal conductivity. Since bismuth expands upon solidification, it is used to make castings for objects subjected to high temperatures. It is used as a replacement for lead in solders, shot for hunting, fishing sinkers, ceramic glazes, and brasses for plumbing applications. It is also used as a carrier for ²³⁵U (an isotope of uranium) fuel in atomic reactors. Ionic compounds of bismuth are used in cosmetics and medicine.

Catherine H. Banks

Bibliography

Greenwood, Norman N., and Earnshaw, A. (1997). Chemistry of the Elements, 2nd edition. Boston: Butterworth-Heinemann.

Lide, David R., ed. (2003). The CRC Handbook of Chemistry and Physics, 84th edition. Boca Raton, FL: CRC Press.

Internet Resources

"Bismuth." U.S. Geological Survey, Mineral Commodity Summaries. Updated January 2003. Available from <http://minerals.usgs.gov/minerals/pubs/commodity/bismuth/110303.pdf>.

bismuth (symbol Bi) Metallic, silvery-white element of group V of the periodic table, first identified as a separate element in 1753. The chief ores are bismite (Bi₂O₃) and bismuthnite (Bi₂S₃). A poor heat conductor, it is put into low-melting alloys for automatic sprinkler systems. Bismuth is also used in insoluble compounds to treat gastric ulcers and skin injuries. It expands when it solidifies, a property exploited in several bismuth alloys for castings. Properties: at.no. 83; r.a.m. 208.98; r.d. 9.75; m.p. 271.3°C (520.3°F); b.p. 1560°C (2840°F); most common isotope Bi²⁰⁹ (100%).

bis·muth / ˈbizmə[unvoicedth]/ • n. the chemical element of atomic number 83, a brittle reddish-gray metal. (Symbol: Bi) ∎  a compound of this element used medicinally.

bismuth (biz-mŭth) n. a white metallic element. Its salts are used in some antacid mixtures and as protective agents in skin powders and pastes. They were formerly widely used in the treatment of syphilis. Symbol: Bi.