Periodic Table -> Tellurium
Tellurium DetailsTellurium Symbol:
TeTellurium Atomic Number:
52Tellurium Atomic Weight:
127.60What is Tellurium?
(atomic number 52, symbol Te) is an element and metalloid (semi-metal) with a silvery white color. It was discovered in 1782 by the mining engineer and mineralogist Franz-Joseph Muller. Pal Kitaibel, a Hungarian chemist and botanist discovered it independently in 1789. It was first isolated by Martin H. Klaproth. The substance was observed in the 17th century, but scientists were unable to isolate it since it showed both non-metallic and metallic properties. The name of the element comes from the word tellus (Earth in Latin). Tellurium and its compounds were studied in detail by the Swedish chemist Jons Jacob Berzelius.
Occurrence and Properties
Tellurium is doped with metals such as silver, gold, tin, and copper. Common oxidation states are -2, +4, and +6, and there are five stable isotopes – Te-126, Te-125, Te-124, Te-123, and Te-122. The boiling point is 1390 °C (2534 °F) and the melting point - 450 °C (842 °F). This element is brittle, with a hexagonal crystal structure and metallic luster. The element belongs to the chalcogens family or oxygen group and forms oxocompounds, halides, polytellurides, tellurides, and organotellurium compounds. Potassium telluride is an odorless solid with a white color while hydrogen telluride is a colorless gas. Sodium telluride is an odorless solid that is white in color.
While the element occurs in nature, it is usually obtained as a byproduct of copper extraction and refining. It also occurs in minerals, including krennerite, calaverite, and sylvanite, and there are tellurium-containing minerals such as tellurate and tellurite. Sylvanite and calverite, for example, are tellurides of gold. Bismuthide maldonite and antimonide aurostibite contain tellurium and gold. Sulfide minerals contain very small amounts. The total annual production amounts to 220 tonnes. Japan, Peru, Canada, and the United States are the main producers.
The element is added to tin, lead, and aluminum alloys for better resistance, strength, and durability. It is also used to produce glasses, solar devices, ceramics, and cast iron. Tellurium has applications in the electronic, semiconductor, and
metallurgy industries and is used to produce thermoelectric devices, chips, modulators, and optical discs. In addition, it is used as an oxidizer and colorant and is added to stainless steel and copper. Adding tellurium to stainless steel makes processing easier. While the element forms many compounds, including sodium telluride, tellurium trioxide, dichloride, and tetrachloride, they have no commercial application. Other compounds, for example, cadmium telluride, are used to manufacture solar panels. The efficiency rating of solar panels is up to 13 percent. In contrast, the rating of silicon panels is up to 9 percent. Photosensitive conductors are produced using mercury, cadmium, and tellurium.
Toxic Compounds and Health Hazards
This element is teratogenic and toxic and must be handled with caution. When inhaled, it can cause side effects such as nausea, garlic odor, and headache. Other side effects include dry mouth, drowsiness, and even poisoning in extreme cases. Long-term exposure leads to vomiting, constipation, abdominal pain, respiratory problems, and eye irritation. Other side effects include garlic-like breath and liver problems. Toxic fumes are released when heated. There are radioactive isotopes as well. Tellurium is produced commercially. It is not considered an environmental hazard and plays no biological role.
Exposure to sodium, potassium, and hydrogen telluride can cause nausea, loss of appetite, and insomnia. Other side effects include metallic taste, dry mouth, and loss of the sweat function. Tellurium hydroxide is a very toxic compound. Long-term exposure is associated with a reduced volume of red blood cells. Long-term exposure is not recommended for persons with skin disease, chronic respiratory problems, blood disorders, and neurological disorders. In laboratory conditions, intoxication causes coma, convulsions, paralysis, and tremors in animals. Note that the compounds of the element are more toxic than tellurium itself. Iron foundry workers report symptoms such as nausea, anorexia, metallic taste, and dryness in the mouth.
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