Crystalline tellurium has a silvery-white appearance, and
exhibits a metallic lustre when pure. 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.
•Name: Tellurium
•Symbol: Te
•Atomic number: 52
•Atomic weight: 127.60 (3) [see note g]
•Standard state: solid at 298 K
•CAS Registry ID: 13494-80-9
•Group in periodic table: 16
•Group name: Chalcogen
•Period in periodic table: 5
•Block in periodic table: p-block
•Color: silvery lustrous grey
•Classification: Semi-metallic
Historical information
Tellurium was discovered by Franz Joseph Muller von Reichstein at 1783 in Romania. Origin of name: from the Latin word "tellus" meaning "earth" (note: tellus and terra were both Latin words for 'earth'. Tellus was a goddess of the earth, and Terra Mater was the Mother Earth). Tellurium was discovered in gold ores by Franz Joseph Mδller von Reichenstein, the chief inspector of mines in Trannsylvania in 1782. However tellurium was named by M. Klaproth, who isolated it in 1798, after he continued Mδller von Reichenstein's work.
Physical properties
•Melting point: 722.66 [or 449.51 °C (841.12 °F)] K
•Boiling point: 1261 [or 988 °C (1810 °F)] K
•Density of solid: 6240 kg m-3
Orbital properties
•Ground state electron configuration: [Kr].4d10.5s2.5p4
•Shell structure: 2.8.18.18.6
•Term symbol: 3P2
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.
Humans exposed to as little as 0.01 mg m-3 in air, or less, develop "tellurium breath", which has a garlic-like odour.
•Name: Tellurium
•Symbol: Te
•Atomic number: 52
•Atomic weight: 127.60 (3) [see note g]
•Standard state: solid at 298 K
•CAS Registry ID: 13494-80-9
•Group in periodic table: 16
•Group name: Chalcogen
•Period in periodic table: 5
•Block in periodic table: p-block
•Color: silvery lustrous grey
•Classification: Semi-metallic
Historical information
Tellurium was discovered by Franz Joseph Muller von Reichstein at 1783 in Romania. Origin of name: from the Latin word "tellus" meaning "earth" (note: tellus and terra were both Latin words for 'earth'. Tellus was a goddess of the earth, and Terra Mater was the Mother Earth). Tellurium was discovered in gold ores by Franz Joseph Mδller von Reichenstein, the chief inspector of mines in Trannsylvania in 1782. However tellurium was named by M. Klaproth, who isolated it in 1798, after he continued Mδller von Reichenstein's work.
Physical properties
•Melting point: 722.66 [or 449.51 °C (841.12 °F)] K
•Boiling point: 1261 [or 988 °C (1810 °F)] K
•Density of solid: 6240 kg m-3
Orbital properties
•Ground state electron configuration: [Kr].4d10.5s2.5p4
•Shell structure: 2.8.18.18.6
•Term symbol: 3P2
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.
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