Bismuth

Bismuth
Name	Bismuth
Number	83
Category	Post-transition metal
Group	15
Appearance	Lustrous silver with a pinkish tinge
Atomic weight	208.98040
Electron configuration	[Xe] 4f14 5d10 6s2 6p3
Phase	Solid
Density gpcm3	9.78
Melting point K	544.7
Boiling point K	1837
Crystal structure	Rhombohedral
Oxidation states	−3, +1, +2, +3, +4, +5
Electronegativity	2.02
Ionization energies	1st: 703 kJ/mol

Bismuth. It is a brittle, crystalline, post-transition metal with a distinctive pinkish-silver hue, known for being one of the few elements that is denser as a liquid than as a solid. Historically confused with lead and tin, it was finally distinguished as a unique element in the mid-18th century by Claude François Geoffroy. With an atomic number of 83, it is the heaviest stable element and is only very weakly radioactive, with an alpha decay half-life vastly exceeding the current age of the universe.

Properties

Bismuth possesses a number of notable physical and chemical characteristics. It has one of the lowest thermal conductivities among metals and the highest Hall coefficient, making it useful in certain thermoelectric and magnetic applications. Its most visually striking property is the colorful, iridescent oxide tarnish that forms on its surface, ranging from yellow to blue, due to thin-film interference. Chemically, it is largely inert and resistant to acids and water, but dissolves in concentrated nitric acid and hot sulfuric acid. In its +3 oxidation state, bismuth forms compounds like bismuth oxychloride and bismuth subsalicylate, which are key to many of its applications.

History

The use of bismuth dates back to the early Middle Ages, where it was often used in incunabula printing and as a pigment in cosmetics. For centuries, it was not distinguished from other metals; Georgius Agricola in the 16th century noted its distinct properties in his work *De Natura Fossilium*. Definitive recognition as a separate element is credited to Claude François Geoffroy, who demonstrated its differences from lead in 1753. Its name is likely derived from the German *"Weisse Masse"* (white mass), later latinized. During the alchemical period, it was associated with the quest for the philosopher's stone.

Occurrence and production

Bismuth rarely occurs in its native metallic form. It is primarily obtained as a by-product from the refining of other metal ores, particularly lead, copper, tin, silver, and gold. Major sources include the minerals bismuthinite and bismite. Leading producers historically have been China, Peru, Mexico, and Bolivia, with significant refining also occurring in Belgium and Japan. Global production is closely tied to the output of the lead smelting and copper mining industries. The United States Geological Survey monitors its reserves, which are estimated to be sufficient for several decades at current usage rates.

Applications

Bismuth has a wide array of modern uses, prized for its low toxicity compared to its neighbors on the periodic table. It is a key component in low-melting-point alloys, such as Wood's metal, used in fire sprinkler systems and electrical fuses. Its compounds are vital in medicine; bismuth subsalicylate is the active ingredient in remedies like Pepto-Bismol. In cosmetics, bismuth oxychloride provides a pearlescent luster. Other applications include a replacement for lead in solder and shotgun pellets, a catalyst in the production of acrylic fiber, and as a dense, transparent material in particle physics detectors like those at CERN.

Biological role and toxicity

Bismuth has no known essential biological role. Its compounds, however, have been used medicinally for centuries due to their low systemic absorption and antimicrobial effects in the gastrointestinal tract. While metallic bismuth and its insoluble salts are considered non-toxic, excessive intake of certain compounds can lead to a condition known as bismuth line on the gums or, in rare historical cases, encephalopathy, as was documented in Australia and France. It is generally regarded as the least toxic of the heavy metals, a property that drives its substitution for lead in an increasing number of industrial and consumer products.

See also

* Periodic table * Post-transition metal * Pepto-Bismol * Solder * Claude François Geoffroy

Category:Chemical elements Category:Post-transition metals