Bismuth

83 lead ← bismuth → polonium Sb ↑ Bi ↓ Uup periodic table
General
Name, Symbol, Number	bismuth, Bi, 83
Chemical series	poor metals
Group, Period, Block	15, 6, p
Appearance	lustrous reddish white
Atomic mass	208.98040(1) g/mol
Electron configuration	[Xe] 4f14 5d10 6s2 6p3
Electrons per shell	2, 8, 18, 32, 18, 5
Physical properties
Phase	solid
Density (near r.t.)	9.78 g/cm³
Liquid density at m.p.	10.05 g/cm³
Melting point	544.7 K (271.5 °C, 520.7 °F)
Boiling point	1837 K (1564 °C, 2847 °F)
Heat of fusion	11.30 kJ/mol
Heat of vaporization	151 kJ/mol
Heat capacity	(25 °C) 25.52 J/(mol·K)
Vapor pressure P/Pa 1 10 100 1 k 10 k 100 k at T/K 941 1041 1165 1325 1538 1835
Atomic properties
Crystal structure	rhombohedral
Oxidation states	3, 5 (mildly acidic oxide)
Electronegativity	2.02 (Pauling scale)
Ionization energies (more)	1st: 703 kJ/mol
	2nd: 1610 kJ/mol
	3rd: 2466 kJ/mol
Atomic radius	160 pm
Atomic radius (calc.)	143 pm
Covalent radius	146 pm
Miscellaneous
Magnetic ordering	diamagnetic
Electrical resistivity	(20 °C) 1.29 µΩ·m
Thermal conductivity	(300 K) 7.97 W/(m·K)
Thermal expansion	(25 °C) 13.4 µm/(m·K)
Speed of sound (thin rod)	(20 °C) 1790 m/s
Speed of sound (thin rod)	(r.t.) 32 m/s
Shear modulus	12 GPa
Bulk modulus	31 GPa
Poisson ratio	0.33
Mohs hardness	2.25
Brinell hardness	94.2 MPa
CAS registry number	7440-69-9
Notable isotopes
Main article: Isotopes of bismuth iso NA half-life DM DE (MeV) DP 207Bi syn 31.55 y ε, β+ 2.399 207Pb 208Bi syn 3,368,000 y ε, β+ 2.880 208Pb 209Bi 100% (1.9±0.2) ×1019y α   205Tl

Bismuth (chemical symbol Bi, atomic number 83) is a brittle, white crystalline metal with a pink tinge. It is chemically similar to arsenic and antimony.

is a chemical element in the periodic table that has the . This heavy, brittle, white crystalline trivalent poor metal has a pink tinge and chemically resembles arsenic and antimony. Of all the metals, it is the most naturally diamagnetic, and only mercury has less thermal conductivity. Lead-free bismuth compounds are used in cosmetics and in medical procedures.

• Among metals, it is the most naturally diamagnetic (exhibits magnetism in the presence of an externally applied magnetic field?).

Notable characteristics

It is a brittle metal with a pinkish hue, and an iridescent oxide tarnish showing many refractive colors from yellow to blue. Among the heavy metals, bismuth is unusual in that its toxicity is much lower than that of its neighbors in the periodic table such as lead, thallium and antimony. Traditionally, it has also been regarded as the element with the heaviest stable isotope, but this is now known to be untrue (see below).

No other metal is more naturally diamagnetic—that is, bismuth has the greatest resistance to being magnetized.

(as opposed to superdiamagnetic) than bismuth. It occurs in its native form, and has a high electrical resistance. Of any metal, it has the second lowest thermal conductivity and the highest Hall effect.

When deposited in sufficiently thin layers on a substrate bismuth is a semiconductor, rather than a poor metal . When combusted with oxygen, bismuth burns with a blue flame and its oxide forms yellow fumes. Bismuth expands on freezing, and was long an important component of low-melting typesetting alloys which needed to expand to fill printing molds.

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 × 10¹⁹ years, meaning that bismuth is very slightly radioactive, with a half-life over a billion times longer than the current estimated age of the universe. Due to this phenomenal half-life, bismuth can be treated as if it is stable and non-radioactive. Ordinary food containing typical amounts of Carbon-14 is many thousands of times more radioactive than bismuth, as are our own bodies. However, the radioactivity is of academic interest because bismuth is one of few elements whose radioactivity was suspected, and indeed theoretically predicted, before being detected in the lab.

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. Basilius Valentinus described some of its uses in 1450. Claude François Geoffroy showed in 1753 that this metal is distinct from lead.

Artificial bismuth was commonly used in place of the actual mineral. It was made by reducing tin into thin plates, and cementing them by a mixture of white tartar, saltpeter, and arsenic, stratified in a crucible over an open fire.

Occurrence

In the Earth's crust, bismuth is about twice as abundant as gold. It is not usually economical to mine it as a primary product. Rather, it is usually produced as a byproduct of the processing of other metal ores, especially lead, but also tungsten or other metal alloys.

The most important ores of bismuth are bismuthinite and bismite. The People's Republic of China is the world's largest producer of bismuth, followed by Mexico and Peru. Canada, Bolivia, and Kazakhstan are smaller producers of bismuth.

The average price for bismuth in 2000 was US$7.70 per kilogram. It is relatively cheap, since like lead (but to a much lesser extent), it is radiogenic, being formed from the natural decay of uranium and thorium (specifically, by way of neptunium-237 or uranium-233).

Applications

Bismuth oxychloride is extensively used in cosmetics and bismuth subnitrate and subcarbonate are used in medicine. Bismuth subsalicylate (Pepto-Bismol®) is used as an antidiarrheal. Some other current 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.
• 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 solidify make them ideal for this purpose.
• Bismuth subnitrate is a component of glazes that produces an iridescent luster finish.
• Bismuth telluride is an excellent thermoelectric material; it is widely used.
• As a replacement propellant for Xenon in Hall effect thrusters.

In the early 1990s, research began to evaluate bismuth as a nontoxic replacement for lead in various applications:

• As noted above, bismuth has been used in solders; its low toxicity will be especially important for solders to be used in food processing equipment.
• As a pigment in artist's oil paint
• As an ingredient of ceramic glazes
• As an ingredient in free-machining brasses for plumbing applications
• As an ingredient in free-cutting steels for precision machining properties
• As a catalyst for making acrylic fibres
• In low-melting alloys used in fire detection and extinguishing systems
• As an ingredient in lubricating greases
• As a dense material for fishing sinkers.
• As the oxide, subcarbonate, or subnitrate in crackling microstars (dragon's eggs) in pyrotechnics.
• In 1997 an antibody conjugate of Bi-213, which has a 45 minute half-life and decays with the emission of an alpha-particle, was used to treat patients with leukemia.
• As a replacement for lead in shot and bullets. The UK, USA, and other countries prohibit the use of lead shot for the hunting of wetland birds, which are prone to lead poisoning from ingestion of lead shot, and bismuth shot is one alternative that provides similar ballistic performance. Bismuth core bullets are also starting to appear for use in indoor shooting ranges, where particles of lead from the bullet impacting the backstop can be a problem. Due to bismuth's crystaline nature, the bismuth bullets shatter into a non-toxic powder on impact, making recovery and recycling easy. The lack of malleability does, however, makes bismuth unsuitable for use in expanding hunting bullets.
• FN Herstal uses bismuth in the projectiles for their FN 303 less-lethal riot gun.

See also

• Bismuth compounds
• Bismuth minerals

External links

• WebElements.com - Bismuth
• "Bismuth Statistics and Information" - United States Geological Survey minerals information for bismuth
• Bismuth breaks half-life record for alpha decay
• Los Alamos National Laboratory - Bismuth

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