[27], Protactinium occurs in uraninite (pitchblende) at concentrations of about 0.3-3 parts 231Pa per million parts (ppm) of ore.[7] Whereas the usual content is closer to 0.3 ppm[28] (e.g. 1/100 ihres Anfangwertes beträgt. [49], Although protactinium is located in the periodic table between uranium and thorium, which both have numerous applications, there are currently no uses for protactinium outside scientific research owing to its scarcity, high radioactivity, and high toxicity. [18][19] The discovery of protactinium completed one of the last gaps in the early versions of the periodic table, proposed by Mendeleev in 1869, and it brought to fame the involved scientists. The chains are interconnected through oxygen and bromine atoms, and each oxygen atom is related to three protactinium atoms. [35] The by-products (such as PaOCl3) are removed by fractional sublimation. [25], Thirty radioisotopes of protactinium have been discovered, the most stable being 231Pa with a half-life of 32,760 years, 233Pa with a half-life of 27 days, and 230Pa with a half-life of 17.4 days. [22] He used two different procedures: in the first one, protactinium oxide was irradiated by 35 keV electrons in vacuum. Heating to higher temperatures in an inert atmosphere decomposes Pa(PO3)4 into the diphosphate PaP2O7, which is analogous to diphosphates of other actinides. Verschijning. Vha. [42], Oxyhalides and oxysulfides of protactinium are known. Det som er fænomenet her er at, U-234 som har en yderst lang halveringstid på 4,47 mia. Download books for free. [17] Thus the name brevium was changed to protoactinium as the new element was part of the decay chain of uranium-235 as the parent of actinium (from Greek: πρῶτος prôtos "first, before"). Grunnstoffet vart oppdaga av mellom anna Otto Hahn og Lise Meitner i 1913. [27][28], In den Jahren 1959 und 1961 wurden von der United Kingdom Atomic Energy Authority (UKAEA) 125 g Protactinium mit einer Reinheit von 99,9 % aus 60 t abgebrannter Kernbrennstäbe in einem 12-stufigen Prozess extrahiert; die Kosten betrugen etwa 500.000 US$. Protactinium metal can be prepared by reduction of its fluoride with calcium,[33] lithium or barium at a temperature of 1300–1400 °C. Protactinium(V) fluoride can be prepared by reacting protactinium oxide with either bromine pentafluoride or bromine trifluoride at about 600 °C, and protactinium(IV) fluoride is obtained from the oxide and a mixture of hydrogen and hydrogen fluoride at 600 °C; a large excess of hydrogen is required to remove atmospheric oxygen leaks into the reaction. One ring can be substituted with a halide atom. Auflage | Nils Wiberg, Egon Wiberg, Arnold Fr. [31], Protactinium-233 is formed upon neutron capture by 232Th. Protactinium ist ein radioaktives Zerfallsprodukt des Urans und findet sich in der Natur in Form der beiden Isotope 231Pa und 234Pa, wobei das Isotop 234Pa in zwei unterschiedlichen Energiezuständen auftreten kann. It is a dense, silvery-gray actinide metal which readily reacts with oxygen, water vapor and inorganic acids. Protactinium also has two nuclear isomers, 217mPa (half-life 1.2 milliseconds) and 234mPa (half-life 1.17 minutes). [28][63], Protactinium is both toxic and highly radioactive and thus all manipulations with it are performed in a sealed glove box. medlemstyper 2014:15. Only about 0.05% of ingested protactinium is absorbed into the blood and the remainder is excreted. [41], More complex protactinium fluorides are also known such as Pa2F9[57] and ternary fluorides of the types MPaF6 (M = Li, Na, K, Rb, Cs or NH4), M2PaF7 (M = K, Rb, Cs or NH4) and M3PaF8 (M = Li, Na, Rb, Cs), all being white crystalline solids. In all these materials, protactinium ions are octahedrally coordinated. Heating the nitrate in air at 400 °C converts it to the white protactinium pentoxide. Similar to uranocene, it can be prepared by reacting protactinium tetrachloride with dipotassium cyclooctatetraenide, K2C8H8, in tetrahydrofuran. Boris F. Myasoedov, Harold W. Kirby, Ivan G. Tananaev: Diese Seite wurde zuletzt am 14. It is an undesired intermediate product in thorium-based nuclear reactors and is therefore removed from the active zone of the reactor during the breeding process. To avoid this, 233Pa is extracted from the active zone of thorium molten salt reactors during their operation, so that it only decays to 233U. Protactinium 231Pa, ein Alphastrahler, entsteht beim Zerfall von 235U (siehe Uran-Actinium-Reihe), das betastrahlende Protactinium 234Pa beim Zerfall von Uran 238U (siehe Uran-Radium-Reihe). Brown-colored protactinium(III) iodide has been reported where protactinium ions are 8-coordinated in a bicapped trigonal prismatic arrangement.[56]. Another phase of this oxide with orthorhombic symmetry has also been reported. Heating PaP2O7 in air to 1400 °C decomposes it into the pentoxides of phosphorus and protactinium. [46] Reduction of protactinium(V) chloride with hydrogen at about 800 °C yields protactinium(IV) chloride – a yellow-green solid which sublimes in vacuum at 400 °C; it can also be obtained directly from protactinium dioxide by treating it with carbon tetrachloride at 400 °C. John Arnold Cranston (working with Frederick Soddy and Ada Hitchins) is also credited with discovering the most stable isotope in 1915, but delayed his announcement due to being called up for service in the First World War.[6]. The protactinium coordination in all its tetrahalides is 8, but the arrangement is square antiprismatic in protactinium(IV) fluoride and dodecahedral in the chloride and bromide. Protactinium was first identified in 1913 by Kazimierz Fajans and Oswald Helmuth Göhring and named brevium because of the short half-life of the specific isotope studied, i.e. Team Tvis Holstebro Sponsor produkter. In particular, 232Th via (n,2n) reactions produce 231Th which quickly (half-life 25.5 hours) decays to 231Pa. ANHANG ZUM ZERTIFIKAT Dieser Anhang identifiziert die Standorte des Managementsystems der Hennigsdorfer Elektrostahlwerke GmbH - Zentrale Dieser Anhang gilt nur in Verbindung mit dem Hauptzertifikat #2019-0090881 und kann nicht ohne dieses protactinium. Seit der Verfügbarkeit moderner, sehr sensibler Massenspektrometer ist eine Anwendung des 231Pa beispielsweise als Tracer in der Paläozeanographie möglich geworden.[33]. 238 Uran Þ 234 Thorium Þ 234 Protactinium Þ 234 Uran Þ 230 Thorium Þ … Exñua 5 Evaç uEraoxnvaT10Thç. From the blood, about 40% of the protactinium Nearly all uranium-238 (99.8%) decays first to the shorter-lived 234mPa isomer. [38] It becomes superconductive at temperatures below 1.4 K.[7][34] Protactinium tetrachloride is paramagnetic at room temperature but turns ferromagnetic upon cooling to 182 K.[39], Protactinium exists in two major oxidation states, +4 and +5, both in solids and solutions, and the +3 and +2 states were observed in some solid phases. In Bezug auf weitere Gefahren wurde dieses Element entweder noch nicht eingestuft oder eine verlässliche und zitierfähige Quelle hierzu wurde noch nicht gefunden. Anmerkung zur Spontanspaltung: Die Daten werden unter der Annahme berechnet, dass Tochterkerne mit 61 % bzw. Im Periodensystem steht es in der Gruppe der Actinoide (7. [45][47], Protactinium iodides result from the oxides and aluminium iodide or ammonium iodide heated to 600 °C. [29] Für viele Jahre war dies die einzig weltweit verfügbare Quelle für Protactinium, von der jeweils verschiedene Laboratorien für wissenschaftliche Untersuchungen versorgt wurden.[8]. R. D. Fowler, B. T. Matthias, L. B. Asprey, H. H. Hill, J. D. G. Lindsay, C. E. Olsen, R. W. White: S. Ganesan, Umasankari Kannan, P. D. Krishnani, V. Jagannathan, R. P. Jain, R. Karthikeyan: J. F. McManus, R. Francois, J.-M. Gherardi, L. D. Keigwin, S. Brown-Leger: R. P. Dodge, G. S. Smith, Q. Johnson, R. E. Elson: CIAAW, Standard Atomic Weights Revised 2013, Proceedings of the Royal Society of London, Berichte der Deutschen Chemischen Gesellschaft, John Albert Cranston, University of Glasgow, Berichte der deutschen chemischen Gesellschaft, https://de.wikipedia.org/w/index.php?title=Protactinium&oldid=201876672, „Creative Commons Attribution/Share Alike“. Zum anderen wurde das Oxid zu den Halogeniden (Chlorid, Bromid oder Iodid) umgesetzt und diese dann im Vakuum an einem elektrisch beheizten Draht reduziert. Protactinium 233Pa ist ein Zwischenprodukt im Brutprozess von Thorium 232Th zu Uran 233U in Thorium-Hochtemperaturreaktoren. [52][53] The pentoxide Pa2O5 combines with rare-earth metal oxides R2O3 to form various nonstoichiometric mixed-oxides, also of perovskite structure. [27][55] The maximum safe dose of Pa in the human body is 0.03 μCi (1.1 kBq), which corresponds to 0.5 micrograms of 231Pa. Protactinium(V)-oxid (Pa2O5) ist ein weißes, kristallines Pulver. Protactinium(V)-chlorid (PaCl5) bildet gelbe monokline Kristalle und besitzt eine Kettenstruktur bestehend aus 7-fach koordinierten pentagonalen Bipyramiden.[34]. [34][35], Protactinium is an actinide which is positioned in the periodic table to the left of uranium and to the right of thorium, and many of its physical properties are intermediate between those two actinides. Es ist silbrig metallisch und wird supraleitend unterhalb von 1,4 K. Es ist radioaktiv und kommt in der Natur extrem selten vor. Protactinium-233 results from the decay of thorium-233 as part of the chain of events used to produce uranium-233 by neutron irradiation of thorium-232. Die größte Menge an Protactinium wird künstlich erzeugt. An alternative reaction is between protactinium pentachloride and hydrogen bromide or thionyl bromide. In het mineraal uraniniet (pekblende) wordt protactinium in een concentratie van ongeveer 0,1 ppm aangetroffen. 234Pa wurde 1913 von Kasimir Fajans und O. H. Göring entdeckt, sie gaben ihm wegen seiner kurzen Halbwertszeit (… Der offizielle Name für alle drei Isotope sowie alle künstlich herstellbaren Isotope mit der Ordnungszahl 91 wurde 1949 von der IUPAC zu Protactinium bestimmt, statt des schwerer auszusprechenden Protoactinium von Hahn und Meitner. The most stable is white pentoxide Pa2O5, which can be produced by igniting protactinium(V) hydroxide in air at a temperature of 500 °C. Protactinium (formerly protoactinium) is a chemical element with the symbol Pa and atomic number 91. Lehrbuch der Anorganischen Chemie, 102. [35] Protactinium forms borohydrides which include Pa(BH4)4. For ease of pronunciation, the name was shortened to protactinium by IUPAC in 1949. [61], With the advent of highly sensitive mass spectrometers, an application of 231Pa as a tracer in geology and paleoceanography has become possible. deposits in the bones, about 15% goes to the liver, 2% to the kidneys, and the rest leaves the body. It was once thought to be able to support a nuclear chain reaction, which could in principle be used to build nuclear weapons: the physicist Walter Seifritz [de] once estimated the associated critical mass as 750±180 kg. ... Uran-238 zerfällt mit einer Halbwertszeit von 4,46 Milliarden Jahren zu Thorium-234 24,1 Tagen zu Protactinium-234 46,69 Stunden zu Uran. Die Quantenmechanik wird nicht nur von Schülern … Deshalb muss sich im Kern von Thorium ein Neutron in ein Proton und ein Elektron aufgespaltet haben. [27][30], Two major protactinium isotopes, 231Pa and 233Pa, are produced from thorium in nuclear reactors; both are undesirable and are usually removed, thereby adding complexity to the reactor design and operation. („zerfällt“). Its major isotope 231Pa has a specific activity of 0.048 curies (1.8 GBq) per gram and primarily emits alpha-particles with an energy of 5 MeV, which can be stopped by a thin layer of any material. [31] Andere Autoren kommen zum Schluss, dass eine Kettenreaktion selbst bei beliebig großer Masse in Protactinium 231Pa nicht möglich ist.[32]. Protactinium carbide PaC is formed by reduction of protactinium tetrafluoride with barium in a carbon crucible at a temperature of about 1400 °C. Am Ende dieser so genannten Zerfallsreihe steht das stabile Blei-206. Ist mein Wert nun komplett falsch, geschweige denn meine Rechnungen, oder sind es die Werte, die mich zu einem solchen Ergebnis geführt haben? a) Bestimmen Sie mit einer grafischen Darstellung die Zerfallskonstante λ und die Halbwertszeit. Beim Protactinium 234 besteht dabei eine Kernisomerie (di erente innere Zustände bei glei- cher Kernladungs- und Massenzahl), die zu zwei unterschiedlichen Halbwertszeiten führen. Det er eit aktinid. Hovudartikkelen for denne kategorien er Protactinium. Dmitri Mendelejew postulierte im Jahre 1871 die Existenz eines Elements zwischen Thorium und Uran. [57] The pentachloride melts at 300 °C and sublimates at even lower temperatures. Subscription will auto renew annually. Cranston, Soddy, The parent of Actinium, Nature, Band 100, 1918, S. 498–499. Die kritische Masse beträgt nach Angabe von Walter Seifritz 750±180 kg. Das Isotop von Uran-234 ist ein Mitglied der Uranreihe. Ich bekam 74s raus für die Halbwertszeit. A more stable isotope of protactinium, 231Pa, was discovered in 1917/18 by Otto Hahn and Lise Meitner, and they chose the name proto-actinium, but the IUPAC finally named it "protactinium" in 1949 and confirmed Hahn and Meitner as discoverers. The thermal expansion, electrical and thermal conductivities of these three elements are comparable and are typical of post-transition metals. The biological half-life of protactinium is about 50 years in the bones, whereas in other organs the kinetics has a fast and slow component. [33][37] The thermal expansion coefficient of the tetragonal phase between room temperature and 700 °C is 9.9×10−6/°C. Analysis of the relative concentrations of various uranium, thorium and protactinium isotopes in water and minerals is used in radiometric dating of sediments which are up to 175,000 years old and in modeling of various geological processes. Der Kern wandelt sich dabei unter Aussendung von Teilchen in einen anderen Kern um oder ändert unter Energieabgabe seinen Zustand. So, nun habe ich aber bei einer anderen Seite gesehen, dass die Halbwertszeit von Protactinium 71s beträgt. Protactinium (verkürzt aus ursprünglich Proto-actinium (griechisch πρώτος (prõtos) = erster und Actinium); Silbentrennung Pro|tac|ti|ni|um oder Pro|t|ac|ti|ni|um) ist ein chemisches Element mit dem Elementsymbol Pa und der Ordnungszahl 91. b) -zuerst rechnete ich um: 6min sind 360s år, kan henfalde til Pa-234 som har en halveringstid på kun 71 sekunder. [35] The dioxide can be converted back to pentoxide by heating in oxygen-containing atmosphere to 1100 °C. Radioaktives Gleichgewicht von Uran-234. [17][18] Unabhängig gelang die Entdeckung des langlebigen Isotops in England Frederick Soddy und John Arnold Cranston, wobei letzterer nicht veröffentlichen konnte, da er 1915 Soldat im Ersten Weltkrieg wurde. The coordination changes to octahedral in the brown protactinium(V) bromide and is unknown for protactinium(V) iodide. So, the ratio of protactinium-231 to thorium-230 is used for radiometric dating of sediments which are up to 175,000 years old and in modeling of the formation of minerals. Protactinium oxides are known for the metal oxidation states +2, +4 and +5. [13][14][15][16][17] In 1917/18, two groups of scientists, Otto Hahn and Lise Meitner of Germany and Frederick Soddy and John Cranston of Great Britain, independently discovered another isotope of protactinium, 231Pa, having a much longer half-life of about 32,000 years. Die Werte für die Eigenschaften (Infobox) sind, wenn nicht anders angegeben, aus. Aber wie kann ein Elektron aus dem Kern kommen? α Alpha-Zerfall (Emission eines Heliumatoms) β- Beta--Zerfall (Emission eines Elektrons) β+ Beta+-Zerfall (Emission eines Positrons) ββ Doppelter Betazerfall (gleichzeitige Emission zweier Elektronen) Seng relativ Atommass ass 231,03588. So, thorium and protactinium, but not uranium compounds are poorly soluble in aqueous solutions, and precipitate into sediments; the precipitation rate is faster for thorium than for protactinium. Density was not measured directly but calculated from the lattice parameters. This bright yellow solid is stable to heating to 800 °C in vacuum. Therefore, uranium was positioned below tungsten in group VI, and thorium below zirconium in group IV, leaving the space below tantalum in group V empty and, until the 1950s, periodic tables were published with this structure. Both +4 and +5 states easily form hydroxides in water with the predominant ions being Pa(OH)3+, Pa(OH)2+2, Pa(OH)+3 and Pa(OH)4, all colorless. Die Bestimmung von Protactinium-233 Hildegard Pluskal Fresenius' Zeitschrift für analytische Chemie volume 162 , pages 127 – 128 ( 1958 ) Cite this article Eine Zerfallsreihe ist allgemein die Abfolge der nacheinander entstehenden Produkte eines radioaktiven Zerfalls.Sie entsteht, indem ein Radionuklid sich in ein anderes, dieses in ein drittes umwandelt usw. Dieses Isotop hat eine Halbwertszeit von nur 2,46 × 10 5 Jahren und gehört daher nicht zu den Urnukliden (im Gegensatz zu 235 U und 238 U ). [35] Protactinium(V) bromide has two similar monoclinic forms, one is obtained by sublimation at 400–410 °C and another by sublimation at slightly lower temperature of 390–400 °C. Angol Főnév. There, the metal atom is sandwiched between two cyclooctatetraene ligands. [9], In 1900, William Crookes isolated protactinium as an intensely radioactive material from uranium; however, he could not characterize it as a new chemical element and thus named it uranium-X (UX). Radioaktivität (von französisch radioactivité; zu lateinisch radiare „strahlen“ und activus „tätig“, „wirksam“; zusammengesetzt also „Strahlungstätigkeit“) ist die Eigenschaft instabiler Atomkerne, spontan ionisierende Strahlung auszusenden. Protactinium(IV)-oxid (PaO2) ist ein schwarzes, kristallines Pulver. Holleman | download | Z-Library. [27], As protactinium is present in small amounts in most natural products and materials, it is ingested with food or water and inhaled with air. His method was still used in the 1950s to isolate 23490Th and 23491Pa from uranium compounds. protactinium-234. Ugrás a navigációhoz Ugrás a kereséshez. Kategori:Protactinium. Hopp til navigering Hopp til søk. [18][24] For many years, this was the world's only significant supply of protactinium, which was provided to various laboratories for scientific studies. ... Ausgangsnuklid der Uran-Radium-Reihe ist Uran-238. [57] As with oxides, protactinium forms mixed halides with alkali metals. Évaç onro- nugvwrÉÇ Y, Exnua öjar.popc- E,nirTÉða. [23] Im Jahre 1934 isolierte er erstmals elementares Protactinium aus 0,1 Milligramm Pa2O5. [12] Protactinium was first identified in 1913, when Kasimir Fajans and Oswald Helmuth Göhring encountered the isotope 234Pa during their studies of the decay chains of uranium-238: 23892U → 23490Th → 23491Pa → 23492U. The last isotope, while not a transuranic waste, has a long half-life of 32,760 years and is a major contributor to the long-term radiotoxicity of spent nuclear fuel. Much higher ratios of 2,000 and above are measured in loam soils and clays, such as bentonite.
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