Bismuth

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Bismuth,  83Bi
20131119 211021.jpg
General properties
Name, symbol Bismuth, Bi
Alternative name Wismuth
Appearance Silvery solid, often with rainbow layer of bismuth oxide.
Bismuth in the periodic table
Sb

Bi

Uup
LeadBismuth → Polonium
Atomic number 83
Standard atomic weight (Ar) 208.98040
Group, block , p-block
Period period 6
Electron configuration [Xe] 4f14 5d10 6s2 6p3
per shell
2, 8, 18, 32, 18, 5
Physical properties
Silvery, rainbow when oxidized.
Phase Solid
Melting point 544.7 K ​(271.5 °C, ​520.7 °F)
Boiling point 1837 K ​(1564 °C, ​2847 °F)
Density at  (0 °C and 101.325 kPa) 9.78 g/cm3 g/L
when liquid, at  10.05 g/cm3
Heat of fusion 11.30 kJ/mol
Heat of 179 kJ/mol
Molar heat capacity 25.52 J/(mol·K)
 pressure
Atomic properties
Oxidation states 5, 4, 3, 2, 1, −1, −2, −3 ​(a mildly acidic oxide)
Electronegativity Pauling scale: 2.02
energies 1st: 703 kJ/mol
2nd: 1610 kJ/mol
3rd: 2466 kJ/mol
Atomic radius empirical: 156 pm
Covalent radius 148±4 pm
Van der Waals radius 207 pm
Miscellanea
Crystal structure ​Rhomboedral
Speed of sound thin rod 1790 m/s (at 20 °C)
Thermal expansion 13.4 µm/(m·K) (at 25 °C)
Thermal conductivity 7.97 W/(m·K)
Electrical resistivity 1.29·10-6 Ω·m (at 20 °C)
Magnetic ordering Diamagnetic
Young's modulus 32 GPa
Shear modulus 12 GPa
Bulk modulus 31 GPa
Poisson ratio 0.33
Mohs hardness 2.25
Brinell hardness 70–95 MPa
CAS Registry Number 7440-69-9
History
Discovery Claude François Geoffroy (1753)
· references

Bismuth is a chemical element with symbol Bi and atomic number 83. It is a post-transition metal, grey and dense. This metal is known to be among the least toxic heavy metals. Bismuth-209 is currently known as isotope with longest decay half-time of all radioactive elements calculated to be (1.9 +/- 0.2 ) x 1019years, which is in good agreement with the theoretical prediction of 4.6 x 1019years.[1]

Properties

Chemical

Bismuth is stable to both dry and moist air at ordinary temperatures. When red-hot, it reacts with water to make bismuth trioxide[2].

2 Bi + 3 H2O → Bi2O3 + 3 H2

Bismuth dissolves in concentrated sulfuric acid to make bismuth(III) sulfate and sulfur dioxide.

2 Bi + 6 H2SO4 → 6 H2O + Bi2(SO4)3 + 3 SO2

Bismuth reacts with halogens to produce bismuth halides. Unlike bismuth trifluoride and bismuth triiodide, bismuth trichloride and bismuth pentafluoride rapidly hydrolyse in moist air and water. Bismuth will react with most acids, but oxygen or hydrogen peroxide has to be present to oxidize the metal.

Physical

Bismuth is a brittle white-silver metal in its pure form. It will oxidize in air to form an iridescent hue, under certain circumstances, showing many colors from yellow to blue. It has the lowest thermal conductivity of all known metals and it is the most diamagnetic pure element. Small samples of bismuth metal can levitate in the presence of strong magnetic fields. Similar to antimony, gallium, germanium and silicon, bismuth is denser in the liquid phase than the solid (like ice), expanding 3.32% on solidification.

Availability

Bismuth is present as bismuth subsalicylate in Pepto-Bismol. It can be extracted from the compound, as shown here.

Large chunks of metal can be bought as Hopper crystals, that display beautiful iridescence.

Bismuth is found in certain electronics, mostly as lead-free solder. The solder that binds the ceramic lid to the CPU appears to be mostly of bismuth, as after melting it and letting it cool in open air it displays the typical iridescence.

Some gun stores advertise shotgun pellets made of bismuth or alloys thereof as "green", or non-toxic ammo, as opposed to lead pellets.

Preparation

Bismuth can be extracted from Pepto-Bismol, by adding acid and then reducing the metal with either aluminium or other reducing metal.

Projects

  • Making bismuth crystals
  • Levitation with magnets

Handling

Safety

Unlike it's surrounding metals (lead, antimony, polonium), bismuth and bismuth compounds have low toxicity. Overexposure to bismuth, however, can result in the formation of a black deposit on the gums, known as a "bismuth line".

Some of its compounds, such as bismuth chloride will hydrolyze in moist air and is corrosive to skin, so protection is required when handling the compound.

Bismuth is technically radioactive; its naturally occurring isotope bismuth-209 is not fully stable. But its half-life is so high and radioactivity so low that it can be considered stable for all intents and purposes. It does not pose a radioactive hazard.

Storage

Bismuth does not require special storage. Hopper crystals can be displayed on any shelf or table.

Disposal

It's best to try to recycle the bismuth and avoid dumping it in the environment.

References

  1. http://physicsworld.com/cws/article/news/2003/apr/23/bismuth-breaks-half-life-record-for-alpha-decay
  2. http://en.wikipedia.org/wiki/Bismuth

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