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 acquires an iridescent oxide tarnish that shows many refractive colors, ranging from yellow to blue. It belongs to the same family of chemical elements as arsenic and antimony and is chemically similar to them. It is a poor conductor of heat and electricity.

This element expands on freezing and was long an important component of low-melting typesetting alloys that needed to expand to fill printing molds.

• 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?).

Occurrence

In the Earth's crust, bismuth is about twice as abundant as gold. In nature, it occurs in its native (free elemental) form, and also as its compounds. It is often associated with the ores of lead, tin, and copper. Its most important ores are bismuthinite (a sulfide) and bismite (an oxide).

It is usually not economical to mine bismuth as a primary product. Rather, it is most often obtained as a byproduct of the processing of other metal ores, especially lead, or other metal alloys. Like lead (but to a much lesser extent), it is radiogenic, being formed from the natural radioactive decay of uranium and thorium (specifically, by the decay of neptunium-237 or uranium-233).

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 this element.

History

Bismuth (New Latin bisemutum, from German Wismuth, perhaps from weiße Masse, "white mass") was confused in early times with tin and lead because of its resemblance to those elements. The German monk Basilius Valentinus described some of its uses in 1450. In 1753, Claude François Geoffroy showed 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.

Notable characteristics

In the periodic table, bismuth is located in group 15 (formerly group 5A), below arsenic and antimony. It is thus a member of the nitrogen family of elements, sometimes called the pnictogens (or pnicogens). In addition, it lies between lead and polonium in period 6.

Among all the metals, bismuth is the most naturally diamagnetic—in other words, it is the most resistant to being magnetized. Also, it has a high electrical resistance. Its thermal conductivity is nearly the lowest among metals—only mercury has a lower value for this property. The toxicity of bismuth is much lower than that of its neighbors in the periodic table, such as lead, thallium, and antimony.

When deposited in sufficiently thin layers on a substrate bismuth acts as a semiconductor, rather than as a poor metal . When bismuth is burned with oxygen, the flame acquires a blue color, and the bismuth trioxide produced forms yellow fumes.

Many isotopes of bismuth are known, ranging in mass number from 184 to 218.

Traditionally, it has also been regarded as the element with the heaviest stable isotope, but this is now known to be untrue (see below). 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.

Hopper crystal: "The edges of hoppered crystals are fully developed, but the interior spaces are not filled in. This results in what appears to be a hollowed out step lattice formation, as if someone had removed interior sections of the individual crystals. In fact, the “removed” sections never filled in, because the crystal was growing so rapidly that there was not enough time (or material) to fill in the gaps. The interior edges of a hoppered crystal still show the crystal form characteristic to the specific mineral, and so appear to be a series of smaller and smaller stepped down miniature versions of the original crystal."

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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