How Does Tellurium Influence Modern Chemistry?
Tellurium Element
The Tellurium element was discovered by Franz Muller Von Reichenstein. Te in the periodic table belongs to group 16. It is a brittle, slightly radioactive, rare metalloid that is silver-white. Tellurium is chalcogen, which is chemically related to selenium and sulfur. It is also discovered as elemental crystals in indigenous form. In the Universe as a whole, Tellurium is much more abundant than on Earth.
When burning in the sunlight, Tellurium delivers a greenish-blue flame. It does not dissolve in water or hydrochloric acid or react with it but dissolves in nitric acid.
There's no biological function for Tellurium. Some fungi, however, use it as a sulfur replacement.
Tellurium is discovered by Franz muller Von Reichenstein.
Physical Properties of Tellurium
Tellurium has two crystalline and amorphous allotropes. Tellurium is silvery-white when crystalline, with a metallic luster. It is a metalloid that is porous and quickly pulverized. Amorphous tellurium is a black-brown powder prepared by precipitating it from a solution of telluric acid or telluric acid Tellurium is a semiconductor that, depending on atomic orientation, exhibits a higher electrical conductivity in some directions; when exposed to light (photoconductivity), the conductivity increases slightly. Tellurium is corrosive to copper, iron, and iron when molten.
Tellurium Symbol-Te
Tellurium atomic number-52
Tellurium atomic mass-127.6 g.mol-1
Electronic configuration- [ Kr ] 4d10 5s25p4
Tellurium Uses
Metallurgy is the largest consumer of tellurium in iron, stainless steel, copper, and lead alloys. The combination of steel and copper creates an alloy that is more machinable than elsewhere. It is alloyed into cast iron for spectroscopy, where the presence of free electrically conductive graphite appears to interfere with the results of spark emission testing. Tellurium in lead increases strength and longevity and reduces the corrosive action of sulfuric acid.
Tellurium shows up in a number of popular photocathodes used in solar-blind photomultiplier tubes and for high brightness photoinjectors driving modern particle accelerators. The Cs-Te photocathode, which is primarily Cs2Te, has a 3.5 eV photoemission threshold and exhibits a rare combination of high quantum efficiency (>10%) and high durability in poor vacuum environments.
For ceramics, Tellurium compounds are used as pigments.
The optical refraction of glass typically used in glass optical fibers for telecommunication is greatly improved by selenides and tellurides.
Selenium and tellurium mixtures are used with barium peroxide as an oxidizer in the electric blasting cap delay powder.
Instead of sulfur or selenium, rubber can be vulcanized with tellurium. Improved heat resistance is shown by the rubber developed in this way.
Tellurite agar is used to classify members of the genus corynebacterium, most specifically the pathogen responsible for diphtheria, Corynebacterium diphtheriae.
Did You Know?
Tellurium and tellurium compounds are considered moderately poisonous and need to be treated with caution, while acute poisoning is rare. Tellurium poisoning is especially difficult to treat because the toxicity of tellurium is increased by certain chelating agents used in the treatment of metal poisoning. It is not confirmed that tellurium is carcinogenic.
FAQs on Tellurium: Properties, Uses, and Importance
1. What is Tellurium and how is it classified in the periodic table?
Tellurium (Te), with atomic number 52, is a chemical element located in Group 16 of the periodic table, along with oxygen, sulfur, selenium, and polonium. It is classified as a metalloid or semimetal. This means it exhibits properties intermediate between those of metals and non-metals. It has a lustrous, crystalline appearance like a metal but is brittle and a poor conductor of heat and electricity, similar to a non-metal.
2. What are the key physical and chemical properties of Tellurium?
Tellurium possesses distinct properties that are aligned with its position in the p-block of the periodic table. Key properties include:
- Physical Properties: It is a silvery-white, brittle, crystalline solid. Tellurium is a semiconductor, meaning its electrical conductivity increases with temperature or exposure to light. It has a melting point of 449.51 °C and a boiling point of 988 °C.
- Chemical Properties: Tellurium is chemically similar to sulfur and selenium. It is resistant to oxidation by air and does not dissolve in most acids, but it does dissolve in nitric acid. It can form compounds in multiple oxidation states, most commonly -2, +2, +4, and +6.
3. What are the most important uses of Tellurium in industry and technology?
The primary importance of Tellurium lies in its use in alloys and as a semiconductor. Its main applications include:
- Alloying Agent: It is added to copper and stainless steel to improve their machinability. When alloyed with lead, it increases resistance to corrosion and fatigue.
- Semiconductors: Tellurium is a key component in advanced semiconductor materials like cadmium telluride (CdTe), which is used in manufacturing highly efficient photovoltaic solar cells.
- Thermoelectric Devices: Bismuth telluride (Bi₂Te₃) is used in thermoelectric devices for both cooling and power generation.
- Vulcanizing Rubber: It is used to speed up the curing process of rubber, making it more durable.
4. Where is Tellurium found in nature and how is it typically extracted?
Tellurium is one of the rarest stable solid elements on Earth. It is not usually found in its native form but is present in minerals like calaverite, sylvanite, and tellurite. However, its primary commercial source is as a by-product of copper and lead refining. During the electrolytic refining of these metals, Tellurium accumulates in the anode sludge. This sludge is then treated through various roasting and leaching processes to isolate and purify the Tellurium metal.
5. How do the properties of Tellurium compare to other elements in Group 16, such as Sulfur and Selenium?
As you move down Group 16 from Sulfur (S) to Selenium (Se) to Tellurium (Te), there is a clear trend from non-metallic to more metallic character.
- Metallic Character: Sulfur is a distinct non-metal, Selenium is also a non-metal but shows some semiconductor properties (like in its grey allotrope), while Tellurium is a true metalloid with more pronounced metallic lustre and semiconductor behaviour.
- Hydrides: The stability of hydrides decreases down the group. H₂S is relatively stable, while hydrogen telluride (H₂Te) is an unstable, toxic gas.
- Oxidation States: All three elements show +4 and +6 oxidation states. However, due to the inert pair effect, the stability of the +6 state decreases down the group, making the +4 state more stable for Tellurium compared to Sulfur.
6. Why is Tellurium considered toxic to humans?
Tellurium and its compounds are considered mildly toxic. The toxicity arises from the body's metabolic process. When ingested or absorbed, the body metabolizes tellurium into dimethyl telluride ((CH₃)₂Te). This compound is then exhaled, resulting in a characteristic and persistent garlic-like odour on the breath and sweat of the exposed individual. While severe poisoning is rare, exposure to high levels can cause drowsiness, nausea, and damage to the nervous system.
7. How does Tellurium's semiconductor nature make it important for solar panel technology?
Tellurium's role as a semiconductor is critical for modern solar technology, specifically in the form of cadmium telluride (CdTe). A semiconductor can conduct electricity under certain conditions but not others, making it an excellent medium for controlling electrical current. In a CdTe solar cell, the CdTe layer acts as the primary light-absorbing material. When photons from sunlight strike this layer, they excite electrons, creating an electrical current. CdTe has a near-ideal band gap for converting sunlight into electricity, making CdTe solar panels highly efficient and cost-effective for large-scale power generation.
