Difference between revisions of "Bismuth"

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Bismuth,  ₈₃Bi

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 ↓ Mc Lead ← Bismuth → 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)
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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-silvery 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

Relevant Sciencemadness threads

• Making bismuth crystals, but they won't oxidize.