|Type:Other Non-Metal, Chalcogen||Atomic weight:127.60|
|Density @ 293 K:6.24 g/cm3||Atomic volume:20.5 cm3/mol|
Tellurium was discovered by Baron Franz Muller von Reichenstein in 1783. Martin H. Klaproth isolated the element and named it in 1798. The element name comes from the Latin word 'tellus', meaning earth.
|State (s, l, g): solid|
|Melting point:723 K (450 °C)||Boiling point:1263 K (990 °C)|
|Specific heat capacity:0.20 J g-1 K-1||Heat of atomization:197 kJ mol-1|
|Heat of fusion:17.490 kJ mol-1||Heat of vaporization : 52.550 kJ mol-1|
|1st ionization energy:869.2 kJ mol-1||2nd ionization energy:1794.6 kJ mol-1|
|3rd ionization energy: 2697.7 kJ mol-1||Electron affinity:190.16 kJ mol-1|
|Shells:2,8,18,18,6||Electron configuration: [Kr] 4d10 5s2 5p4|
|Minimum oxidation number:-2||Maximum oxidation number:6|
|Min. common oxidation no.:0||Max. common oxidation no.:6|
|Electronegativity (Pauling Scale):2.1||Polarizability volume:5.5 Å3|
|Hardness: 2.3 mohs|
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.
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.
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.
|Reaction with air:mild, w/ht ⇒ TeO2||Reaction with 6 M HCl:none|
|Reaction with 15 M HNO3:mild , ⇒ Te(IV)||Reaction with 6 M NaOH:|
|Oxide(s):TeO2, TeO3||Chloride(s):Te2Cl, Te3Cl2, Te4Cl16|
|Hydride(s):TeH2 (hydrogen telluride)|
|Atomic radius:142 pm||Ionic radius (1+ ion):pm|
|Ionic radius (2+ ion):pm||Ionic radius (3+ ion):pm|
|Ionic radius (2- ion):207 pm||Ionic radius (1- ion):pm|
|Thermal conductivity:3 W m-1 K-1||Electrical conductivity: 0.02 x 106 S cm-1|
|Abundance earth's crust: 1 part per billion by weight, 0.2 parts per billion by moles|
|Abundance solar system: parts per billion by weight, part per billion by moles|
|Cost, pure:$24 per 100g|
|Cost, bulk:$ per 100g|
Tellurium is sometimes found free in nature. More commonly, it is found combined with metals, such as in the minerals calaverite (gold telluride, AuTe2) and sylvanite (silver-gold telluride). Commercially, tellurium is obtained as a byproduct of electrolytic copper refining.
Tellurium has 33 isotopes whose half-lives are known, with mass numbers 106 to 138. Of these, five are stable: 120Te, 122Te, 124Te, 125Te and 126Te.