Tellurium
| Topics: |
Geology (main)
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Contents
Background
Tellurium is a metallic, silvery-white element. Some even describe its appearance as "very metallic." Its atomic number is 52 and its symbol is Te. It was discovered in 1783 by Baron Franz Joseph Muller von Reichenstein of Romania, the chief inspector of mines in Transylvania at the time. Tellurium is very brittle and easily pulverized. It does not react with air (Atmospheric composition and structure) or water.
As a commodity, tellurium is used in industry as pure tellurium metal, tellurium dioxide (TeO2), and alloyed (that is, mixed) with other metals.
Tellurium has no known benefit to humans. It does have a strange effect on humans, though. When tellurium is ingested, even in very small amounts, it causes very bad, garlic-smelling breath and body odor.
There are a very small number of tellurium minerals. It combines with oxygen to form tellurite, and with gold and silver to form sylvanite (Au,Ag)Te2. The most common gold telluride mineral is called calaverite (AuTe2).
Name
| Previous Element: Antimony Next Element: Iodine |
| |
| Physical Properties | ||
|---|---|---|
| Color | Silvery | |
| Phase at Room Temp. | solid | |
| Density (g/cm3) | 6.25 | |
| Hardness (Mohs) | 2.3 | |
|
Melting Point (K) |
722.7 | |
|
Boiling Point (K) |
1263 | |
| Heat of Fusion (kJ/mol) | 13.5 | |
| Heat of Vaporization (kJ/mol) | --- | |
| Heat of Atomization (kJ/mol) | 197 | |
| Thermal Conductivity (J/m sec K) | 11.54 | |
| Electrical Conductivity (1/mohm cm) | 0 | |
| Source | Zn/Pb smelting by-product | |
| Atomic Properties | ||
| Electron Configuration | [Kr]4d105s25p4 | |
|
Number of Isotopes |
8 | |
| Electron Affinity (kJ/mol) | 190.16 | |
| First Ionization Energy (kJ/mol) | 869.2 | |
| Second Ionization Energy (kJ/mol) | 1794.6 | |
| Third Ionization Energy (kJ/mol) | 2697.7 | |
| Electronegativity | 2.1 | |
| Polarizability (Å3) | 5.5 | |
| Atomic Weight | 127.6 | |
| Atomic Volume (cm3/mol) | 20.4 | |
| Ionic Radius2- (pm) | 207 | |
| Ionic Radius1- (pm) | --- | |
| Atomic Radius (pm) | 142 | |
| Ionic Radius1+ (pm) | --- | |
| Ionic Radius2+ (pm) | --- | |
| Ionic Radius3+ (pm) | --- | |
| Common Oxidation Numbers | -2,+2,+4,+6 | |
| Other Oxid. Numbers | +5 | |
| Abundance | ||
| In Earth's Crust (mg/kg) | 1×10-3 | |
| In Earth's Ocean (mg/L) | No data available | |
| In Human Body (%) | near 0% | |
| Regulatory / Health | ||
| CAS Number | 13494-80-9 | |
| OSHA Permissible Exposure Limit (PEL) | TWA: 0.1 mg/m3 | |
| OSHA PEL Vacated 1989 | TWA: 0.1 mg/m3 | |
|
NIOSH Recommended Exposure Limit (REL) |
TWA: 0.1 mg/m3 IDLH: 25 mg/m3 | |
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Sources: |
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The name tellurium came from the Latin word tellus meaning earth.
Sources
Tellurium is recovered from the residue produced in refining blister copper from deposits containing recoverable amounts of tellurium. There are large quantities of tellurium in some gold and lead deposits, but the tellurium is not being recovered from these at this time. In addition, tellurium is present in coal and some lower-grade copper deposits, but the cost of recovering the tellurium from these deposits is too high to make it worth the effort. These deposits are called subeconomic deposits.
Top nations producing tellurium and tellurium dioxide are the Russia, Sweden and Japan. As with most commodities, companies in the United States import tellurium. Of the tellurium imported each year, most comes from the United Kingdom, followed by Philippines, Belgium, Canada, and a number of other nations.
Uses
Half of the tellurium consumed each year is used to improve the machinability of special iron and steel products. It is alloyed with copper to make copper more ductile (that is, easier to stretch into wires), and with lead to prevent corrosion. These, and other nonferrous tellurium alloys, account for approximately 10% of tellurium use. Tellurium is also used to make catalysts and chemicals. Some of these chemicals are used in the petroleum industry and in making rubber. Tellurium is added to selenium-based photoreceptors to broaden the spectral range of copiers. Tellurium is also used in other electronic applications such as solar panels, and in the production of blasting caps for explosives.
Substitutes and Alternative Sources
Selenium, bismuth and lead can be used in place of tellurium in many of its metallurgical uses. Selenium and sulfur can be used in place of tellurium in the production of rubber.
Further Reading
- Common Minerals and Their Uses, Mineral Information Institute.
- More than 170 Mineral Photographs, Mineral Information Institute.
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