Tellurium is a chemical element that has the symbol Te and atomic number 52.
A brittle, mildly toxic, silver-white metalloid which looks similar to tin, tellurium is chemically related to selenium and sulphur. Tellurium was discovered in 1782 by Franz-Joseph Müller von Reichenstein in a mineral containing gold and tellurium. Martin Heinrich Klaproth named the new element in 1798. Tellurium is 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.
Tellurium has no biological function, although fungi can incorporate it in place of sulphur and selenium into amino acids such as telluro-cysteine and telluro-methionine. In humans, tellurium is partly metabolised into dimethyl telluride, (CH3)2Te, a gas with a garlic-like odour which is exhaled in the breath of victims of tellurium toxicity or exposure.
When crystalline, tellurium is silvery-white and when it is in pure state it has a metallic luster. It is a brittle and easily pulverized metalloid. Amorphous tellurium is found by precipitating it from a solution of tellurous or telluric acid (Te(OH)6). Tellurium is a p-type semiconductor that shows a greater electrical conductivity in certain directions which depends on atomic alignment; the conductivity increases slightly when exposed to light (photoconductivity). When in its molten state, tellurium is corrosive to copper, iron and stainless steel.
Naturally occurring tellurium has eight isotopes. Four of those isotopes, 122Te, 124Te, 125Te and 126Te, are stable. The other four, 120Te, 123Te, 128Te and 130Te, have been observed to be radioactive. The stable isotopes make up only 33.2 % of the naturally occurring tellurium; this is possible due to the long half-lives of the unstable isotopes. The 128Te isotope has the longest half life among all radioisotopes.
There are 38 known nuclear isomers of tellurium with atomic masses that range from 105 to 142. Tellurium is the lightest element known to undergo alpha decay, with isotopes 106Te to 110Te being able to undergo this mode of decay. The atomic mass of tellurium (127.60 g·mol−1) exceeds that of the following element iodine (126.90 g·mol−1.
The base value of each unit of ranges between 1 and 35Ð per unit, with up to 3 units being found at any one time.
Presence on Mars: Rare
|Group 1 | Group 2 | Group 3 | Group 4 | Group 5 | Group 6|
|Group 3|||Antimony | Astatine | Barium | Bismuth | Cesium | Francium | Hafnium | Indium | Iodine | Iridium | Lanthanum | Lead | Mercury | |Osmium | Platinum | Polonium | Radium | Radon | Rhenium | Tantalum | Tellurium | Thallium | Tin | Tungsten | Xenon||