astatine atomic mass
, With oxygen, there is evidence of the species AtO− and AtO+ in aqueous solution, formed by the reaction of astatine with an oxidant such as elemental bromine or (in the last case) by sodium persulfate in a solution of perchloric acid. Any astatine present at the formation of the Earth has long since disappeared; the four naturally occurring isotopes (astatine-215, -217, -218 and -219) are instead continuously produced as a result of the decay of radioactive thorium and uranium ores, and trace quantities of neptunium-237.  The polyhalides PdAtI2, CsAtI2, TlAtI2, and PbAtI are known or presumed to have been precipitated. The electron configuration of the astatine is [Xe] 4f14 5d10 6s2 6p5. Boiling point: unknown 8. Astatine is a radioactive element and it is a member of group 17 and period 6 in the periodic table. Other physical properties have been predicted from theory and by extrapolation from the properties of other elements. Atomic Mass: (210.0) amu.  That would be consistent with the electronegativity of astatine on the Allred–Rochow scale (1.9) being less than that of hydrogen (2.2). An initial attempt to fluoridate astatine using chlorine trifluoride resulted in formation of a product which became stuck to the glass. Melting point of Astatine is 302 °C and its the boiling point is 337 °C. There are 39 known isotopes of astatine, with atomic masses (mass numbers) of 191–229. The atomic number of astatine is 85 and it is represented by symbol At. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope At-219 (Astatine, atomic number Z = 85, mass number A = 219). It is found on the periodic table as At, with it's atomic number of 85, and can be located at family (column) 17 and period (row) 6. Small amounts of astatine exist in nature as a result of the decay of uranium and thorium, although the total amount of astatine in the earth's crust at any particular time is less than 30 grams. Other designation techniques are sometimes used. Atomic mass is an absolute mass, relative isotopic mass is a number without proportions and without units. Ii vigyan article ek chhota panna hae. , The most stable isotope is astatine-210, which has a half-life of 8.1 hours. Astatine (At) Atomic Data for Astatine (At) Atomic Number = 85 Atomic Weight = 210 Reference E95 : Isotope : Mass : Abundance : Spin : Mag Moment : 210 At: 209.987126: 0: 5 : 221 At: 210.987469: 0: 9/2 : At I Ground State 1s 2 2s 2 2p 6 3s 2 3p 6 3d 1 0 4s 2 4p 6 … In a plasma ion source mass spectrometer, the ions [AtI]+, [AtBr]+, and [AtCl]+ have been formed by introducing lighter halogen vapors into a helium-filled cell containing astatine, supporting the existence of stable neutral molecules in the plasma ion state. However, wet extraction methods are being examined for use in production of larger quantities of astatine-211, as it is thought that wet extraction methods can provide more consistency. Noble Gases L−1. Unlike iodine, astatine also shows a tendency to be taken up by the lungs and spleen, possibly because of in-body oxidation of At– to At+. Name This means that, if decay modes other than alpha are omitted, then astatine-210 has an alpha decay half-life of 4,628.6 hours (128.9 days) and astatine-211 has one of only 17.2 hours (0.7 days). The astatine atomic number is 85. Chemistry of Astatine (Z=85) Last updated; Save as PDF Page ID 575; Contributors and Attributions; Astatine formerly known as alabamine.  Astatine is also thought to be capable of forming cations in salts with oxyanions such as iodate or dichromate; this is based on the observation that, in acidic solutions, monovalent or intermediate positive states of astatine coprecipitate with the insoluble salts of metal cations such as silver(I) iodate or thallium(I) dichromate. The algorithm used to generate the Allred-Rochow scale fails in the case of hydrogen, providing a value that is close to that of oxygen (3.5).  Oxidation of the element with dichromate (in nitric acid solution) showed that adding chloride turned the astatine into a molecule likely to be either AtCl or AtOCl. Higher temperatures of up to around 850 °C may increase the yield, at the risk of bismuth contamination from concurrent volatilization. Chlorine, Iodine and Bromine are the other elements in the halogen family. 1.  This cation exists as a coordination complex in which two dative covalent bonds separately link the astatine(I) centre with each of the pyridine rings via their nitrogen atoms. Beta particles have much greater penetrating power through tissues than do the much heavier alpha particles. It belongs to the halogen family. , In 1940, the Swiss chemist Walter Minder announced the discovery of element 85 as the beta decay product of radium A (polonium-218), choosing the name "helvetium" (from Helvetia, the Latin name of Switzerland). Contamination with astatine-210 is expected to be a drawback of this method. Phase at room temperature: solid 6. , Corson and his colleagues classified astatine as a metal on the basis of its analytical chemistry. A direct identification of some astatine compounds has been made by mass spectrometry. Astatine is an element in the periodic table with atomic no. "m1" means that this state of the isotope is the next possible one above – with an energy greater than – the ground state. Note that, each element may contain more isotopes, therefore this resulting atomic mass is calculated from naturally-occuring isotopes and their abundance. Astatine-211 has potential for targeted alpha-particle therapy, since it decays either via emission of an alpha particle (to bismuth-207), or via electron capture (to an extremely short-lived nuclide, polonium-211, which undergoes further alpha decay), very quickly reaching its stable granddaughter lead-207. 85 and atomic mass 210 gram/mol. , P Durbin, Human Radiation Studies: Remembering the Early Years, 1995, Several obstacles have been encountered in the development of astatine-based radiopharmaceuticals for cancer treatment. Copyright © 1996-2012 Yinon Bentor. Only a few compounds with metals have been reported, in the form of astatides of sodium, palladium, silver, thallium, and lead. Redistilling the condensate may be required to minimize the presence of bismuth (as bismuth can interfere with astatine labeling reactions). It has no stable isotopes and was first synthetically produced (1940) at the University of California. Astatine ek chemical element hae, jiske symbol At, atomic number 85, aur atomic weight 210 hae.  As mentioned, there are grounds for instead referring to this compound as astatine hydride. The reactions involved have been typically tested with dilute solutions of astatine mixed with larger amounts of iodine. The methods summarized below are modern adaptations of older procedures, as reviewed by Kugler and Keller. Astatine is extremely rare in nature, and in fact, there is only about an ounce (about a teaspoonful) in the earth's crust at any one moment. ) 5 82 ] Scientists tried to find it in nature ; its. Comprises of astatine have been prepared with At–B bonds, these being more than. 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