![]() ![]() Alternatively, the halogen may be removed from the target by chemical methods, such as dissolving in nitric acid, with the latter being removed by boiling.Īnother procedure involves the use of a metallic thorium target, which-after bombardment-is dissolved in concentrated hydrochloric acid containing hydrogen fluoride and chlorine. If an aqueous solution of astatine is desired, the element may be separated by washing with an appropriate aqueous solution. The free element begins to distill at 271 ☌ (520 ☏, or the melting point of bismuth), but the operation is best carried out at 800 ☌ (1,500 ☏) with subsequent redistillation. From this, astatine may readily be removed by distillation in air from a stainless-steel tube. Metallic bismuth may be used as a target material. Which indicates that bismuth-209 takes up one alpha particle and emits x neutrons to form an isotope of astatine, whose atomic weight depends on the number of neutrons lost. SpaceNext50 Britannica presents SpaceNext50, From the race to the Moon to space stewardship, we explore a wide range of subjects that feed our curiosity about space!ġ18 Names and Symbols of the Periodic Table Quiz.Learn about the major environmental problems facing our planet and what can be done about them! Saving Earth Britannica Presents Earth’s To-Do List for the 21st Century.100 Women Britannica celebrates the centennial of the Nineteenth Amendment, highlighting suffragists and history-making politicians.COVID-19 Portal While this global health crisis continues to evolve, it can be useful to look to past pandemics to better understand how to respond today.Student Portal Britannica is the ultimate student resource for key school subjects like history, government, literature, and more.This Time in History In these videos, find out what happened this month (or any month!) in history.#WTFact Videos In #WTFact Britannica shares some of the most bizarre facts we can find.Demystified Videos In Demystified, Britannica has all the answers to your burning questions.Britannica Classics Check out these retro videos from Encyclopedia Britannica’s archives.Britannica Explains In these videos, Britannica explains a variety of topics and answers frequently asked questions.There should be tiny quantities of astatine in the earth's crust as products of other radioactive decays, but their existence would be short-lived. Not much is known about the chemical properties of astatine but it is expected to react like the other halogens, although much less vigorously, and it should be more metallic than iodine. ![]() ![]() The most stable isotope of astatine is 210 which has a half-life of 8.1 hours. Astatine 211 is the product and has a half-life of 7.2 hours. The element can be produced by bombarding targets made of bismuth-209 with high energy alpha particles (helium nuclei). It is radioactive and its name, from the Greek astatos, means "unstable". Name Origin: From the Greek word astatos (unstable)Īstatine is the last of the known halogens and was synthesized in 1940 by Corson and others at the University of California. It has no stable isotopes and was first synthetically produced (1940) at the University of California. ![]()
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