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Title: Chemistry/Elements/Tellurium - Wikipedia: Tellurium Properties of the element, including its history, applications, and characteristics.
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Tellurium

From Wikipedia, the free encyclopedia Jump to: navigation, search 52antimony ← tellurium → iodineSe↑Te↓PoPeriodic Table - Extended Periodic TableGeneralName, Symbol, Numbertellurium, Te, 52Element categorymetalloidsGroup, Period, Block16, 5, pAppearancesilvery lustrous grayStandard atomic weight127.60(3)  g·mol−1Electron configuration[Kr] 5s2 4d10 5p4Electrons per shell2, 8, 18, 18, 6Physical propertiesPhasesolidDensity (near r.t.)6.24  g·cm−3Liquid density at m.p.5.70  g·cm−3Melting point722.66 K(449.51 °C, 841.12 °F)Boiling point1261 K(988 °C, 1810 °F)Heat of fusion17.49  kJ·mol−1Heat of vaporization114.1  kJ·mol−1Specific heat capacity(25 °C) 25.73  J·mol−1·K−1Vapor pressureP(Pa)1101001 k10 k100 kat T(K)  (775)(888)10421266Atomic propertiesCrystal structurehexagonalOxidation states±2, 4, 6(mildly acidic oxide)Electronegativity2.1 (Pauling scale)Ionization energies(more)1st:  869.3  kJ·mol−12nd:  1790  kJ·mol−13rd:  2698  kJ·mol−1Atomic radius140  pmAtomic radius (calc.)123  pmCovalent radius135  pmVan der Waals radius206 pmMiscellaneousMagnetic orderingnonmagneticThermal conductivity(300 K)(1.97–3.38)  W·m−1·K−1Speed of sound (thin rod)(20 °C) 2610 m/sYoung's modulus43  GPaShear modulus16  GPaBulk modulus65  GPaMohs hardness2.25Brinell hardness180  MPaCAS registry number13494-80-9Most-stable isotopesMain article: Isotopes of telluriumisoNAhalf-lifeDMDE (MeV)DP120Te0.09%>2.2×1016yε ε1.701120Sn121Tesyn16.78 dε1.040121Sb122Te2.55%122Te is stable with 70 neutrons123Te0.89%>1.0×1013 yε0.051123Sb124Te4.74%124Te is stable with 72 neutrons125Te7.07%125Te is stable with 73 neutrons126Te18.84%126Te is stable with 74 neutrons127Tesyn9.35 hβ-0.698127I128Te31.74%2.2×1024 yβ−β−0.867128Xe129Tesyn69.6 minβ-1.498129I130Te34.08%7.9×1020 yβ−β−2.528130XeReferencesTellurium (pronounced /tɪˈlʊəriəm/, /tɛl-/) is a chemical element that has the symbol Te and atomic number 52. A brittle silver-white metalloid which looks like tin, tellurium is chemically related to selenium and sulfur. Tellurium is primarily used in alloys and as a semiconductor.

Contents

1 Characteristics2 Applications3 History4 Occurrence5 Compounds6 Isotopes7 Precautions8 References9 External links//

[edit] Characteristics

Tellurium is extremely rare, one of the nine rarest metallic elements on earth. It is in the same chemical family as oxygen, sulfur, selenium, and polonium (the chalcogens).When crystalline, tellurium is silvery-white and when it is in its pure state it has a metallic luster. This 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). However, there is some debate whether this form is really amorphous or made of minute crystals.

[edit] Applications

Tellurium is a p-type semiconductor that shows a greater conductivity in certain directions which depends on atomic alignment. Chemically related to selenium and sulfur, the conductivity of this element increases slightly when exposed to light (photoelectric effect).It can be doped with copper, gold, silver, tin, or other metals. When in its molten state, tellurium is corrosive to copper, iron, and stainless steel.Tellurium gives a greenish-blue flame when burned in normal air and forms tellurium dioxide as a result.Metal alloys [1]It is mostly used in alloys with other metals. It is added to lead to improve its strength and durability, and to decrease the corrosive action of sulfuric acid.When added to stainless steel and copper it makes these metals more workable. It is alloyed into cast iron for chill control.Other uses:Used in ceramics.It is used in chalcogenide glasses.Tellurium is used in blasting capsOrganic tellurides have been employed as initiators for living radical polymerisation and electron-rich mono- and di-tellurides possess antioxidant activity.Tellurite agar is used to identify member of the corynebacterium genus, most typically Corynebacterium diphtheriae, the pathogen responsible for diptheriaHigh purity metalorganics of both selenium and tellurium are used in the semiconductor industry, and are prepared by adduct purification.[2][3]Semiconductor and electronic industry uses:Tellurium as a tellurium suboxide is used in the media layer of several types of rewritable optical discs, including ReWritable Compact Discs (CD-RW), ReWritable Digital Video Discs (DVD-RW) and ReWritable Blu-ray Discs. [4] [5]Tellurium is used in the new phase change memory chips developed by Intel. Also see here.Bismuth telluride (Bi2Te3) is used in thermoelectric devices.Tellurium is used in cadmium telluride (CdTe) solar panels. NREL lab tests using this material achieved some of the highest efficiencies for solar cell electric power generation. First Solar Inc. started massive commercial production of CdTe solar panels in recent years, significantly increased tellurium demand. If some of the cadmium in CdTe is replaced by zinc then CdZnTe is formed which is used in solid-state x-ray detectors.Alloyed with both cadmium and mercury, to form mercury cadmium telluride, an infrared sensitive semiconductor material is formed. Organotellurium compounds such as dimethyl telluride, diethyl telluride, diisopropyl telluride, diallyl telluride and methyl allyl telluride are used as precursors for MOVPE growth of II-VI compound semiconductors. Diisopropyl telluride (DIPTe) is employed as the preferred precursor for achieving the low temperature growth of CdHgTe by MOVPE.

[edit] History

Tellurium (Latin tellus meaning "earth") was discovered in 1782 by the Hungarian Franz-Joseph Müller von Reichenstein (Müller Ferenc) in Nagyszeben (now, Sibiu) Transylvania. In 1789, another Hungarian scientist, Pál Kitaibel, also discovered the element independently, but later he gave the credit to Müller. In 1798, it was named by Martin Heinrich Klaproth who earlier isolated it.[6]Tellurium was used as a chemical bonder in the making of the outer shell of the first atom bomb. The 1960s brought growth in thermoelectric applications for tellurium, as well as its use in free-machining steel, which became the dominant use.

[edit] Occurrence

Tellurium on quartz (Moctezuma, Sonora, Mexico)With an abundance in the Earth's crust even lower than platinum, tellurium is, apart from the precious metals, the rarest stable solid element in the earth's crust. Its abundance in the Earth's crust is 1 to 5 ppb, compared with 5 to 37 ppb for platinum. By comparison, even the rarest of the lanthanides have crustal abundances of 500 ppb.The extreme rarity of tellurium in the Earth's crust is not a reflection of its cosmic abundance, which is in fact greater than that of rubidium[1], even though rubidium is ten thousand times more abundant in the Earth's crust. Rather, the extraordinarily low abundance of tellurium on Earth results from the fact that, during the formation of the Earth, the stable form of elements in the absence of oxygen and water was controlled by the oxidation and reduction of hydrogen. Under this scenario elements such as tellurium which form volatile hydrides were severely depleted during the formation of the Earth's crust through evaporation. Tellurium and selenium are the heavy elements most depleted in the Earth's crust by this process.[citation needed]Tellurium is sometimes found in its native (elemental) form, but is more often found as the tellurides of gold (calaverite, krennerite, petzite, sylvanite, and others). Tellurium compounds are the only chemical compounds of gold found in nature, but tellurium itself (unlike gold) is also found combined with other elements (in metallic salts). The principal source of tellurium is from anode sludges produced during the electrolytic refining of blister copper. It is a component of dusts from blast furnace refining of lead. Treatment of 500 tons of copper ore typically yields one pound of tellurium. Tellurium is produced mainly in the United States, Canada, Peru, and Japan. See here.Commercial-grade tellurium is usually marketed as minus 200-mesh powder but is also available as slabs, ingots, sticks, or lumps. The year-end price for tellurium in 2000 was US$14 per pound. In recent years, tellurium price was driven up by increased demand and limited supply, reaching as high as US$100 per pound in 2006. See also here.See also: Telluride, Colorado, category:Telluride minerals

[edit] Compounds

Tellurium is in the same series as sulfur and selenium and forms similar compounds. A compound with metal or hydrogen and similar ions is called a telluride. Gold and silver tellurides are considered good ores. Compounds with tellurate ions complexes TeO42- or TeO66- are known as tellurates. Also tellurites TeO32-. Also tellurols –TeH, named with prefix tellanyl- or suffix -tellurol.See also: Category:Tellurium compoundsEnlarged view of tellurium crystal

[edit] Isotopes

Main article: isotopes of telluriumThere are 30 known isotopes of tellurium with atomic masses that range from 108 to 137. Naturally found tellurium consists of eight isotopes (listed in the table to the right); three of them are observed to be radioactive. 128Te has the longest known half-life, 2.2×1024 years[7], among all radioactive isotopes.[8]

[edit] Precautions

Tellurium and tellurium compounds should be considered to be mildly toxic and need to be handled with care.Acute poisoning is rare.[9] Tellurium is not reported to be carcinogenic.[9]Humans exposed to as little as 0.01 mg/m3 or less in air develop "tellurium breath", which has a garlic-like odor.[10] The garlic odor that is associated with human intake of tellurium compounds is caused from the tellurium being metabolized by the body. When the body metabolizes tellurium in any oxidation state, the tellurium gets converted into dimethyl telluride. Dimethyl telluride is volatile and produces the garlic-like smell. Even though the metabolic pathways of tellurium are not known, it is generally assumed that they resemble those of the more extensively studied selenium, because the final methylated metabolic products of the two elements are similar.

[edit] References

^ George, Micheal W. (2007). "Mineral Yearbook 2007: Selenium and Tellurium". United States geological Survey.^ Journal of Crystal Growth 93: 744–749. 1988. doi:10.1016/0022-0248(88)90613-6. ^ U.S. Patent 5,117,021  Method for purification of tellurium and selenium alkyls^ Farivar, Cyrus (2006-10-19). "Panasonic says that its 100GB Blu-ray discs will last a century". Retrieved on 2008-11-13.^ Kenichi Nishiuchi, Hideki Kitaura, Noboru Yamada and Nobuo Akahira (1998). "Dual-Layer Optical Disk with Te–O–Pd Phase-Change Film". Jpn. J. Appl. Phys. 37: 2163-2167. doi:10.1143/JJAP.37.2163. ^ Diemann, Ekkehard; Müller, Achim; Barbu, Horia (2002). "Die spannende Entdeckungsgeschichte des Tellurs (1782 - 1798) Bedeutung und Komplexität von Elemententdeckungen". Chemie in unserer Zeit 36 (5): 334–337. doi:10.1002/1521-3781(200210)36:5<334::AID-CIUZ334>3.0.CO;2-1. ^ "WWW Table of Radioactive Isotopes: Tellurium". Nuclear Science Division, Lawrence Berkeley National Laboratory (2008).^ "Noble Gas Research". Laboratory for Space Sciences, Washington University in St. Louis (2008).^ a b Harrison, W; S Bradberry, J Vale (1998-01-28). "Tellurium" (HTML). International Programme on Chemical Safety. Retrieved on 2007-01-12.^ "Tellurium" (HTML). Los Alamos National Laboratory (2003-12-15). Retrieved on 2007-01-12.

[edit] External links

Sister projectWikimedia Commons has media related to: TelluriumLook up tellurium inWiktionary, the free dictionary.WebElements.com – TelluriumUSGS Mineral Information on Selenium and TelluriumSelenium Tellurium Development AssociationComprehensive Data on Telluriumv • d • ePeriodic tableH HeLiBe BCNOFNeNaMg AlSiPSClArKCa ScTiVCrMnFeCoNiCuZnGaGeAsSeBrKrRbSr YZrNbMoTcRuRhPdAgCdInSnSbTeIXeCsBaLaCePrNdPmSmEuGdTbDyHoErTmYbLuHfTaWReOsIrPtAuHgTlPbBiPoAtRnFrRaAcThPaUNpPuAmCmBkCfEsFmMdNoLrRfDbSgBhHsMtDsRgUubUutUuqUupUuhUusUuoUueUbn Alkali metalsAlkaline earth metalsLanthanoidsActinoidsTransition metalsOther metalsMetalloidsOther nonmetalsHalogensNoble gasesRetrieved from "http://en.wikipedia.org/wiki/Tellurium" Categories: Metalloids | Chalcogens | Chemical elements | TelluriumHidden categories: All articles with unsourced statements | Articles with unsourced statements since October 2008 Views Article Discussion Edit this page History Personal tools Log in / create account if (window.isMSIE55) fixalpha(); Navigation Main page Contents Featured content Current events Random article Search   Interaction About Wikipedia Community portal Recent changes Contact Wikipedia Donate to Wikipedia Help Toolbox What links here Related changesUpload fileSpecial pages Printable version Permanent linkCite this page Languages Afrikaans العربية Azərbaycan বাংলা Беларуская Bosanski Български Català Česky Corsu Dansk Deutsch Eesti Ελληνικά Español Esperanto Euskara Français Furlan Gaeilge Gaelg Galego 한국어 Հայերեն हिन्दी Hrvatski Ido Bahasa Indonesia Íslenska Italiano עברית Basa Jawa ಕನ್ನಡ Kiswahili Latina Latviešu Lëtzebuergesch Lietuvių Lojban Magyar മലയാളം मराठी Nederlands 日本語 ‪Norsk (bokmål)‬ ‪Norsk (nynorsk)‬ Occitan O'zbek Plattdüütsch Polski Português Română Runa Simi Русский Sicilianu Simple English Slovenčina Slovenščina Српски / Srpski Srpskohrvatski / Српскохрватски Suomi Svenska தமிழ் ไทย Tiếng Việt Türkçe Українська 中文 Powered by MediaWiki Wikimedia Foundation This page was last modified on 14 November 2008, at 16:15. All text is available under the terms of the GNU Free Documentation License. (See Copyrights for details.) Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a U.S. registered 501(c)(3) tax-deductible nonprofit charity. Privacy policy About Wikipedia Disclaimers if (window.runOnloadHook) runOnloadHook();
 

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