Tellurium

Symbol: Te Atomic Number: 52 Atomic Symbol: 127.6



A brittle, silvery-white metallic element usually found in combination with gold and other metals, produced commercially as a byproduct of the electrolytic refining of copper and used to alloy stainless steel and lead, in ceramics, and, in the form of bismuth telluride, in thermoelectric devices.

Tellurium is commercially primarily used in alloys, foremost in steel and copper to improve machinability. Applications in __solar panels__ and as a semiconductor material also consume a considerable fraction of tellurium production. Other uses of Tellurium are to color glass and ceramics. It is added to lead to increase its strength and increase its resistance to sulfuric acid.

When this metallic element is heated at a high enough level to decompose tellurium chloride can emit toxic fumes of tellurium and chlorine. Tellurium's melting point is 450 degrees celsius where as its boiling point is at 1390 degrees celsius.

History: Tellurium was discovered in Transylvania in 1782 by Franz-Joseph Müller von Reichenstein in a mineral containing tellurium and gold. Martin Heinrich Klaproth named the new element in 1798 after the Latin word for "earth", //tellus//. Gold telluride minerals are the most notable natural gold compounds. However, they are not a commercially significant source of tellurium itself, which is normally extracted as by-product of copper and lead production.

Harmful effects: Tellerium is very toxic and teratogenic (can cause harm to developing embryos). Exposure to as little as 0.01 mg/m2 or less in air leads to "tellurium breath", which has a garlic-like odor. Characteristics: Tellurium is a rare, silvery-white, brittle, lustrous metalloid. It burns in air with a greenish-blue flame and forms tellurium dioxide (TeO2). Tellurium is a semiconductor material and is slightly photosensitive. It forms many compounds corresponding to those of sulfur and selenium, the elements above it in the periodic table. Tellurium has radioactive isotopes and is the lightest element to exhibit alpha decay.

Uses of Tellurium
Tellurium is alloyed with copper and stainless steel to make these metals more workable. It is added to lead to decreases the corrosive action of sulfuric acid and to improve its strength and hardness. Tellurium is used as a coloring agent in ceramics. Tellurium is also used in the electronic industry, for example with cadmium and mercury to form photosensitive semiconductors. It is used in vulcanizing rubber and in catalysts for petroleum cracking and in blasting caps for explosives. It has no biological function, but fungi can use it in place of sulfur and selenium to make amino acids such as telluro-cysteine and telluro-methionine. Most organisms break down tellurium into dimethyl telluride which has been found in hot springs.

Tellurium is usually the example of gold and other metals.
 * Symbol:** Te **Atomic Number:** 52 **Atomic Mass:** 127.6 amu **Melting Point:** 449.5 °C (722.65 K, 841.1 °F) **Boiling Point:** 989.8 °C (1262.95 K, 1813.64 °F) **Number of Protons/Electrons:** 52 **Number of Neutrons:** 76 **Classification:** Metalloid **Crystal Structure:** Hexagonal **Density @ 293 K:** 6.24 g/cm3 **Color:** silverish

Atomic Structure

 * [[image:http://www.chemicalelements.com/bohr/b0052.gif width="309" height="306"]] ||  || **Number of Energy Levels:** 5
 * First Energy Level:** **Second Energy Level:** **Third Energy Level:** **Fourth Energy Level:** **Fifth Energy Level:** ||

Isotopes

 * ** Isotope ** || ** Half Life ** ||
 * Te-119 || 4.69 days ||
 * Te-120 || Stable ||
 * Te-121 || 16.8 days ||
 * Te-121m || 154.0 days ||
 * Te-122 || Stable ||
 * Te-123 || 1.3E12 years ||
 * Te-123m || 119.7 days ||
 * Te-124 || Stable ||
 * Te-125 || Stable ||
 * Te-125m || 58.0 days ||
 * Te-126 || Stable ||
 * Te-127 || 9.4 hours ||
 * Te-127m || 109.0 days ||
 * Te-128 || Stable ||
 * Te-129 || 1.16 hours ||
 * Te-129m || 33.6 days ||
 * Te-130 || 2.5E21 years ||
 * Te-131 || 25.0 minutes ||
 * Te-131m || 1.35 days ||
 * Te-132 || 3.26 days ||
 * Te-133 || 12.4 minutes ||
 * Te-133m || 55.4 minutes ||
 * Te-134 || 41.8 minutes ||

Facts

 * Date of Discovery:** 1782 **Discoverer:** Franz Muller von Reichenstein **Name Origin:** From the Greek word //tellus// (Earth) **Uses:** coloring of glass and ceramics, thermoelectric devices **Obtained From:** by-product of refining of lead and copper

Tellurium monoxide was first reported in 1883 as a black amorphous solid formed by the heat decomposition of TeSO3 in vacuum, disproportionating into tellurium dioxide, TeO2 and elemental tellurium upon heating.[24home][25home] Since then, however, some doubt has been cast on its existence in the solid phase, although it is known as a vapor phase fragment; the black solid may be merely an equimolar mixture of elemental tellurium and tellurium dioxide.[26home] Tellurium dioxide is formed by heating tellurium in air, causing it to burn with a blue flame.[20home] Tellurium trioxide, β- TeO3, is obtained by thermal decomposition of Te(OH)6. The other two forms of trioxide reported in the literature, the α- and γ- forms, were found not to be true oxides of tellurium in the +6 oxidation state, but a mixture of Te4+, OH− and O − 2 .[27home] Tellurium also exhibits mixed-valence oxides, Te2O5 and Te4O9 .[27home] The tellurium oxides and hydrated oxides form a series of acids, including tellurous acid ( H2TeO3 ), orthotelluric acid ( Te(OH)6 ) and metatelluric acid ( (H2TeO4)//n// ).[26home] The two forms of telluric acid form //tellurate// salts containing the TeO 2– 4 and TeO 6− 6 anions, respectively. Tellurous acid forms //tellurite// salts containing the anion TeO 2− 3. Other tellurium cations include TeF 2+ 8, which consists of two fused tellurium rings and the polymeric TeF 2