Elemental Bismuth
Bi
Atomic No. - 83
The most common bismuth minerals are 'bismuthinite' and 'bismite.'
The History Says
The name 'bismuth' might have been derived from New Latin 'bisemutum' or from German 'Wismuth,' which mean white metal, or meadow mines. 'Wismuth,' as name, occured in German records several hundred years before the metal's identification as a separate element. It indicates that the properties of bismuth were recognised earlier.
The Present Scenario
Bismuth produced in the United States is obtained as a by-product of copper, gold, silver, tin and especially lead ore processing.
Bismuth, a silvery-white metallic element was long thought to be a variety of lead or tin due to its resemblance. In 1753, a chemist named Claude Geoffroy, showed it as a separate element.
Bismuth is relatively brittle for a metal. It shows a pinkish tint on freshly-broken surfaces. It is less dense as a solid than it is as a liquid. It expands while cooling and this property makes it in more commercial uses. It is a poor conductor of electricity and heat, and is relatively corrode in the atmosphere, unless it is attacked by some strong acid.
Bismuth is non-toxic and occurs naturally. Native bismuth is rare and does not occur in large quantities. Often it combines with other elements and forms minerals like bismithunite (bismuth sulfide, Bi2S3) and bismite (bismuth oxide, Bi2O3).
Physical Properties of Bismuth
| Phase | Solid |
| Color | Silver white, often with a multi-colored iridescent tarnish. |
| Luster | Metallic |
| Transparency | Crystals are opaque. |
| Cleavage | Perfect in one direction (basal). |
| Fracture | Uneven or jagged. |
| Hardness | 2 - 2.5 |
| Specific gravity | 9.7 - 9.8 (generally heavy even for metallic minerals). |
| Streak | Silver to white. |
| Density (near room temperature) | 9.78 g/cm3 |
| Liquid density at melting point | 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) |
Atomic Properties of Bismuth
| Crystal structure | Rhombohdral |
| Oxidation states | 3, 5 (mildly acidic oxide) |
| Electronegativity | 2.02 (Pauling scale) |
| Ionization energies | 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 |
Uses of Bismuth
- In cosmetics as bismuth oxychloride.
- In medicine as bismuth subnitrate and subcarbonate.
- Bismuth subsalicylate is used as an antidiarrheal.
- Strong permanent magnets are made from the alloy bismano (MnBi).
- Many alloys of bismuth have low melting points and hence they are used for fire detection and suppression system safety devices.
- In producing malleable irons.
- In making acrylic fibers.
- Used as a thermocouple material.
- A carrier for U-235 or U-233 fuel in nuclear reactors.
- Used in solders.
- Bismuth subnitrate, a component of glazes produces an iridescent luster finish.
- In the production of shot and shotgun slugs.
Substitutes and Alternative Sources of Bismuth
In medical applications, bismuth is substituted by magnesia, alumina and antibiotics. Scientists have also discovered that a glass bulb when filled with glycerine, it can substitute bismuth as the triggering mechanism for fire sprinkler systems.
The element indium is also used in place of bismuth in the manufature of low-temperature solders. But, indium is very expensive while bismuth is much cheaper.
Occurrences of Bismuth
The most important ores of bismuth are bismuthinite and bismite. The US produces bismuth as a by-product of copper, gold, silver, tin and especially lead ore processing. The following are the major producers of bismuth in the world:
- Australia
- San Baldomero and La Paz, Bolivia
- Devon, England
- Germany
- South Dakota, Colorado and California in the USA
- Canada
- Japan
- Mexico
- Peru