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Bismuth

2007 Schools Wikipedia Selection. Related subjects: Chemical elements


               83                 lead ← bismuth → polonium
               Sb
               ↑
               Bi
               ↓
               Uup

                                  Periodic Table - Extended 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] 4f^14 5d^10 6s^2 6p^3
                                   Electrons per shell 2, 8, 18, 32, 18, 5
                                                       Physical properties
                                                               Phase solid
                                       Density (near r.t.) 9.78 g·cm^−3
                                   Liquid density at m.p. 10.05 g·cm^−3
                                                    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^−1
                                     Heat of vaporization 151 kJ·mol^−1
                          Heat capacity (25 °C) 25.52 J·mol^−1·K^−1

   CAPTION: 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^−1
                                                    2nd: 1610 kJ·mol^−1
                                                    3rd: 2466 kJ·mol^−1
                                                      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^−1·K^−1
                       Thermal expansion (25 °C) 13.4 µm·m^−1·K^−1
                               Speed of sound (thin rod) (20 °C) 1790 m/s
                                                    Young's modulus 32 GPa
                                                      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
                                                         Selected isotopes

                 CAPTION: 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% (19 ± 2) ×10^18 y α                ^205Tl

                                                                References

   Bismuth ( IPA: [ˈbɪzməθ]) 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. 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.

Notable characteristics

   It is a brittle metal with a pinkish hue, often occurring in its native
   form with 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. No other metal is more
   naturally diamagnetic (as opposed to superdiamagnetic) than bismuth,
   and it 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.

   While bismuth was traditionally regarded as the element with the
   heaviest stable isotope, it had long been thought to be unstable on
   theoretical grounds. Not until 2003 was this demonstrated when
   researchers at the Institut d'Astrophysique Spatiale in Orsay, France,
   measured the alpha emission half-life of {} ^209Bi to be 19 x 10^18
   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 its extraordinarily long half-life, for nearly all
   applications bismuth can be treated as if it is stable and
   non-radioactive. 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 laboratory.

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 hammering 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 sometimes used in cosmetics. Also bismuth
   subnitrate and bismuth subcarbonate are used in medicine. Bismuth
   subsalicylate (Pepto-Bismol®) is used as an antidiarrheal and to treat
   some other gastro-intestinal diseases.

   Some other current uses are:
     * Strong permanent magnets can be made from the alloy bismanol
       (BiMn).
     * Many bismuth alloys have low melting points and are widely used for
       fire detection and suppression system safety devices.
     * Bismuth is used as an alloying agent in production of 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, carbonite, or nitrite in crackling microstars (
       dragon's eggs) in pyrotechnics.
     * In 1997 an antibody conjugate with 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
       many other countries now prohibit the use of lead shot for the
       hunting of wetland birds, as other creatures in the wetlands are
       prone to lead poisoning from ingestion of lead shot. Bismuth-tin
       alloy shot is one alternative that provides similar ballistic
       performance to lead (another less expensive but also
       poorer-performing alternative is steel shot, although some prefer
       it for the increased damgage it does).
       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, make bismuth unsuitable for use in expanding hunting
       bullets.
     * FN Herstal uses bismuth in the projectiles for their FN 303
       less-lethal riot gun.

   Retrieved from " http://en.wikipedia.org/wiki/Bismuth"
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