Tellurium 52 Te 127.60(3)   Switch element to... actinium aluminium aluminum americium antimony argon arsenic astatine barium berkelium beryllium bismuth bohrium boron bromine cadmium caesium calcium californium carbon cerium cesium chlorine chromium cobalt copper curium darmstadtium dubnium dysprosium einsteinium erbium europium fermium fluorine francium gadolinium gallium germanium gold hafnium hassium helium holmium hydrogen indium iodine iridium iron krypton lanthanum lawrencium lead lithium lutetium magnesium manganese meitnerium mendelevium mercury molybdenum neodymium neon neptunium nickel niobium nitrogen nobelium osmium oxygen palladium phosphorus platinum plutonium polonium potassium praseodymium promethium protactinium radium radon rhenium rhodium roentgenium rubidium ruthenium rutherfordium samarium scandium seaborgium selenium silicon silver sodium strontium sulfur sulphur tantalum technetium tellurium terbium thallium thorium thulium tin titanium tungsten ununbium ununhexium ununoctium ununpentium ununquadium ununtrium uranium vanadium xenon ytterbium yttrium zinc zirconium Go adjacent... As Se Br Sb Te I Bi Po At

The essentials

Description 

Here is a brief description of tellurium.

• Standard state: solid at 298 K
• Colour: silvery lustrous grey
• Classification: Semi-metallic
• Availability:

Crystalline tellurium has a silvery-white appearance, and exhibits a metallic lustre when pure (see above). It is brittle and easily pulverised. Tellurium is a p-type semiconductor, and shows varying conductivity with crystal alignment. Its conductivity increases slightly with exposure to light. It can be doped with silver, copper, gold, tin, or other elements.

Humans exposed to as little as 0.01 mg m^-3 in air, or less, develop "tellurium breath", which has a garlic-like odour.

Isolation

It is not usually necessary to make tellurium in the laboratory as it is commercially available. While there are some tellurium ores, most tellurium is made as a byproduct of copper refining. Extraction is complex since the method emplyed will depend upon what other compounds or elements are present. The first step usually involves an oxidation in the presence of sodium carbonate (soda ash).

Cu₂Te + Na₂CO₃ + 2O₂ → 2CuO + Na₂TeO₃ + CO₂

The tellurite Na₂TeO₃ is acidified with sulphuric acid and the tellurium precipitates out as the dioxide (leaving and selenous acid, H₂SeO₃, in solution). Tellurium is liberated from the dioxide by dissolving in sodium hydroxide, NaOH, and electroytic reduction.

TeO₂ + 2NaOH → Na₂TeO₃ + H₂O → Te + 2NaOH + O₂

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