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| Bismuth is a chemical element in the periodic table that has the symbol Bi and atomic number 83. This heavy, brittle, white crystalline trivalent poor metal has a pink tinge and chemically resembles arsenic and antimony. Most diamagnetic of all metals, bismuth has the lowest thermal conductivity of all the elements except mercury. Lead-free bismuth compounds are used in cosmetics and in medical procedures. |
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Notable characteristics
It is a brittle metal with a pinkish hue with an iridescent tarnish. Among the heavy metals, it is the heaviest and the only non-toxic. No other metal is more diamagnetic than bismuth, except mercury. This metal, which occurs in its native form, has a high electrical resistance and also has the highest Hall effect of any metal (that is, it has the greatest increase in electrical resistance when it is placed in a magnetic field). When heated in air bismuth burns with a blue flame and its oxide forms yellow fumes.
Bismuth has long been thought to be unstable on theoretical grounds, but not until 2003 was this demonstrated when researchers at the Institut d'Astrophysique Spatiale in Orsay, France measured the alpha emission half-life of Bi-209 to be (1.9 ± 0.2) × 1019 years, meaning that bismuth is not truly stable, though in effect it is. Due to this phenomenal half-life, the use of bismuth in (eg) certain medicines poses no radiological hazard. Any food containing the normal amount of carbon 14 is many thousands of times more radioactive than bismuth. However, the radioactivity was of academic interest because bismuth is one of few elements whose radioactivity was suspected, and indeed theoretically predicted, rather than detected in the lab.
An immortal who lost a digestive bacterium every year, or a hair every several thousand years, would lose mass more rapidly than a sample of bismuth decays.
Applications
Bismuth oxychloride is extensively used in cosmetics and bismuth subnitrate and subcarbonate are used in medicine. Bismuth subsalicylate is a bright pink liquid used as an antidiarrheal. [1] (http://www.healthcentral.com/mhc/top/001852.cfm)
Some other uses are:
* Strong permanent magnets can be made from the alloy bismanol (MnBi).
* Many bismuth alloys have low melting points and are widely used for fire detection and suppression system safety devices.
* Bismuth is used in producing malleable irons.
* Bismuth is finding use as a catalyst for making acrylic fibers.
* Also used as a thermocouple material.
* A carrier for U-235 or U-233 fuel in nuclear reactors.
* Bismuth has also been used in solders. The fact that bismuth and many of its alloys expand slightly when they freeze make them ideal for this purpose.
* Bismuth subnitrate is a component of glazes that produces an iridescent luster finish.
In the early 1990s, research began on the evaluation of bismuth as a nontoxic replacement for lead in such uses as ceramic glazes, fishing sinkers, food processing equipment, free-machining brasses for plumbing applications, lubricating greases, and shot for waterfowl hunting.
Crystals
Though virtually unseen in nature, high-purity bismuth can form into distinctive hopper crystals. These colorful laboratory creations are typically sold to hobbyists.
History
Bismuth (New Latin bisemutum from German Wismuth, perhaps from weisse Masse, "white mass") was confused in early times with tin and lead due to its resemblance to those elements. Claude Geoffroy Junine showed in 1753 that this metal is distinct from lead.
Occurrence
The most important ores of bismuth are bismuthinite and bismite. Canada, Bolivia, Japan, Mexico, and Peru are major producers. Bismuth produced in the United States is obtained as a by-product of copper, gold, lead, silver, tin and especially lead ore processing. The average price for bismuth in 2000 was US$ 7.70 per kilogram.
This article is licensed under the GNU Free Documentation License.
It uses material from the Wikipedia article "Bismuth". |
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