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Astatine
Astatinemelting point: 302°C Astatine is a radioactive halogen (the heaviest of the halogen elements) and is a solid at room temperature. Dale R. Carson, K. R. MacKenzie, and Emilio Segrè of the University of California produced the element in 1940 by bombarding an isotope of bismuth (209Bi) with alpha particles. The origin of the name "astatine" is the Greek word astatos, which means "unstable." Astatine is found in only vanishingly small amounts in nature—it is believed that only 30 grams (1 ounce) of the element are present in Earth's crust at any one time. It is produced naturally when the elements uranium and thorium decay. Astatine can also be produced in a nuclear reactor by the method used by its discoverers, according to the following reaction: 209 83Bi + 42 He → 211 85At + 2 10n The most stable isotope of astatine is 210At, which has a half-life of 8.1 hours. Other isotopes have mass numbers ranging from 193 to 223 and half-lives ranging from 125 nanoseconds (213At) to 7.2 hours (211At). Astatine is known to form interhalogen compounds with bromine (AtBr), chlorine (AtCl), and iodine (AtI). Additional compounds (HAt and CH3At) have also been detected. Because of its scarcity and short half-life, there were no commercial uses for astatine as of 2003. Researchers are investigating astatine as a means of treating various cancers (e.g., lethal brain tumors) and diseases. Because of its similarities to iodine, which accumulates in the thyroid, it is believed that the element could be utilized to treat certain thyroid diseases. see also Halogens; Radioactivity. Stephanie Dionne Sherk BibliographyLide, David R., ed. (2003). The CRC Handbook of Chemistry and Physics, 84th edition. Boca Raton, FL: CRC Press. Internet ResourcesGagnon, Steve. "It's Elemental: Astatine." Jefferson Lab. Available from <http://education.jlab.org/itselemental/iso085.html>. |
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Sherk, Stephanie Dionne. "Astatine." Chemistry: Foundations and Applications. 2004. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. Sherk, Stephanie Dionne. "Astatine." Chemistry: Foundations and Applications. 2004. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1G2-3400900042.html Sherk, Stephanie Dionne. "Astatine." Chemistry: Foundations and Applications. 2004. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3400900042.html |
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astatine
astatine (symbol At) Semimetallic radioactive element that is one of the halogens (group VII of the periodic table). It is rare in nature, and is found in radioactive decay. At211 will collect in the thyroid gland and is used in medicine as a radioactive tracer. Properties: at.no. 85; r.a.m. 211; m.p. 302°C (575.6°F); b.p. 377°C (710.6°F); most stable isotope At210 (half-life 8.3hr).
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"astatine." World Encyclopedia. 2005. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. "astatine." World Encyclopedia. 2005. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O142-astatine.html "astatine." World Encyclopedia. 2005. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O142-astatine.html |
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Periodic Table of the Elements: Astatine
Periodic Table of the Elements: Astatine
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"Periodic Table of the Elements: Astatine." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. "Periodic Table of the Elements: Astatine." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1E1-At-ptblTABLE.html "Periodic Table of the Elements: Astatine." The Columbia Encyclopedia, 6th ed.. 2011. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1E1-At-ptblTABLE.html |
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astatine
astatine
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"astatine." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. "astatine." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O233-astatine.html "astatine." Oxford Dictionary of Rhymes. 2007. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O233-astatine.html |
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