Density was not measured directly but calculated from the lattice parameters. 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. Thus, instead of rapidly decaying to the useful 233U, a significant fraction of 233Pa converts to non-fissile isotopes and consumes neutrons, degrading the reactor efficiency. [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. Commons har multimedia som gjeld: Protactinium. Vha. Man weiß, dass bei diesem ß-Zerfall Protactinium 234 mit 91 Protonen entsteht. [42], Oxyhalides and oxysulfides of protactinium are known. 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. Hopp til navigering Hopp til søk. [8] For a long time chemists searched for eka-tantalum as an element with similar chemical properties to tantalum, making a discovery of protactinium nearly impossible. Das Isotop von Uran-234 ist ein Mitglied der Uranreihe. 2, Fluorinated materials for energy conversion, "The Preparation of Some Protactinium Compounds and the Metal", Solid state physics: advances in research and applications, Concise encyclopedia of magnetic and superconducting materials, Journal of the Chemical Society, Dalton Transactions, Nuclear Instruments and Methods in Physics Research A, "A Re-calculation of Criticality Property of, "Collapse and rapid resumption of Atlantic meridional circulation linked to deglacial climate changes", https://en.wikipedia.org/w/index.php?title=Protactinium&oldid=996514786, Chemical elements predicted by Dmitri Mendeleev, Short description is different from Wikidata, Creative Commons Attribution-ShareAlike License, This page was last edited on 27 December 2020, at 01:49. These compounds easily hydrolyze in water. [7] The actinide element group was unknown at the time. [51] The monoxide PaO has only been observed as a thin coating on protactinium metal, but not in an isolated bulk form. 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. Bis in die 1950er Jahre wurde das Periodensystem in dieser Form dargestellt. In Bezug auf weitere Gefahren wurde dieses Element entweder noch nicht eingestuft oder eine verlässliche und zitierfähige Quelle hierzu wurde noch nicht gefunden. und irgendwann zerfällt; Polonium 210 zu Blei 206 und Blei 206 ist stabil. [60] However, the possibility of criticality of 231Pa has been ruled out since then. For the small alkali cations like Na, the crystal structure is tetragonal, whereas it lowers to orthorphombic for larger cations K+, Rb+, Cs+ or NH4+. Protactinium oxides are known for the metal oxidation states +2, +4 and +5. [33][37] The thermal expansion coefficient of the tetragonal phase between room temperature and 700 °C is 9.9×10−6/°C. It is obtained by reacting protactinium(V) chloride with a mixture of hydrogen sulfide and carbon disulfide at 900 °C. Protactinium (formerly protoactinium) is a chemical element with the symbol Pa and atomic number 91. [7][10][11] Crookes dissolved uranium nitrate in ether, and the residual aqueous phase contains most of the 23490Th and 23491Pa. 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“. 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 ). Es ist silbrig metallisch und wird supraleitend unterhalb von 1,4 K. Es ist radioaktiv und kommt in der … Bemerkungen: Uran-234 (historisch: Uran II, U II) wird durch β--Zerfall von Protactinium-234 als Zwischenglied der Uran-Radium-Reihe gebildet. etc. Man kann also ver-einfacht sagen, dass sich die Hälfte der Menge des Elements Uran-238 innerhalb von 4,47 Milliarden Jahren in das Element Blei-206 verwandelt. Das zuerst entstehende Nuklid wird Tochternuklid genannt, das dem Tochternuklid folgende Enkelnuklid, das dem Enkelnuklid folgende Urenkelnuklid usw. a) Bestimmen Sie mit einer grafischen Darstellung die Zerfallskonstante λ und die Halbwertszeit. Protactinium also has two nuclear isomers, 217mPa (half-life 1.2 milliseconds) and 234mPa (half-life 1.17 minutes). [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. [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. Juli 2020 um 18:41 Uhr bearbeitet. Zerfallsreihen können oft über viele Elemente hinweg reichen. [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. All of the remaining isotopes have half-lives shorter than 1.6 days, and the majority of these have half-lives less than 1.8 seconds. Tantalum's heavier analogue was later found to be the transuranic element dubnium – which, however, does not react like tantalum, but like protactinium. [45] PaOS is a light-yellow non-volatile solid with a cubic crystal lattice isostructural to that of other actinide oxysulfides. Die von der Radioaktivität ausgehenden Gefahren gehören nicht zu den einzustufenden Eigenschaften nach der GHS-Kennzeichnung. [35][51] The black dioxide PaO2 is obtained from the pentoxide by reducing it at 1550 °C with hydrogen. 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. [40] Other known protactinium ions include PaCl2+2, PaSO2+4, PaF3+, PaF2+2, PaF−6, PaF2−7 and PaF3−8.[41][42]. Das bedeutet, dass sich innerhalb dieses Zeitraums genau die Hälfte der ursprünglich vorhandenen Stoffmenge an Uran-238 ("Mutter-Nuklid") in das Element Thorium-234 ("Tochter-Nuklid") umwandelt. The longest-lived and most abundant (nearly 100%) naturally occurring isotope of protactinium, protactinium-231, has a half-life of 32,760 years and is a decay product of uranium-235. [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 7 of protactinium originates from the 5 halide atoms and two bonds to protactinium atoms belonging to the nearby chains. It interacts with the intermediate filament protein vimentin, a substrate for the PKC family of protein kinases, and with hPKCI-1, an inhibitor of the PKCs. Much smaller trace amounts of the short-lived protactinium-234 and its nuclear isomer protactinium-234m occur in the decay chain of uranium-238. So, nun habe ich aber bei einer anderen Seite gesehen, dass die Halbwertszeit von Protactinium 71s beträgt. Tryggleik. The coordination is the same in protactinium(V) chloride, but the color is yellow. PaOBr3 has a monoclinic structure composed of double-chain units where protactinium has coordination 7 and is arranged into pentagonal bipyramids. Im Periodensystem steht es in der Gruppe der Actinoide (7. Alphazerfall - Lexikon der Physi . Protactinium reagerer langsomt med atmosfærisk luft. The estimated shear modulus of protactinium is similar to that of titanium. There, within one polymeric chain, all the halide atoms lie in one graphite-like plane and form planar pentagons around the protactinium ions. Protactinium, ein radioaktives Zerfallsprodukt des Urans, findet sich in der Natur in Form der beiden Isotope 231Pa und 234Pa, wobei das Isotop 234Pa in zwei unterschiedlichen Energiezuständen auftreten kann. deposits in the bones, about 15% goes to the liver, 2% to the kidneys, and the rest leaves the body. Auch Letzteres gilt nur, wenn es sich um eine dafür relevante Stoffmenge handelt. This bright yellow solid is stable to heating to 800 °C in vacuum. Team Tvis Holstebro Sponsor produkter. Beim Protactinium 234 besteht dabei eine Kernisomerie (di erente innere Zustände bei glei- cher Kernladungs- und Massenzahl), die zu zwei unterschiedlichen Halbwertszeiten führen. Subscription will auto renew annually. [23] Im Jahre 1934 isolierte er erstmals elementares Protactinium aus 0,1 Milligramm Pa2O5. [18][24] For many years, this was the world's only significant supply of protactinium, which was provided to various laboratories for scientific studies. Brown-colored protactinium(III) iodide has been reported where protactinium ions are 8-coordinated in a bicapped trigonal prismatic arrangement.[56]. år, kan henfalde til Pa-234 som har en halveringstid på kun 71 sekunder. 234 U: 2.195 MeV Bemerkungen: Das Nuklid Protactinium-234 (historisch: Uran Z, UZ) entsteht natürlich durch IT-Zerfall (γ-Emmission) des Protactinium-234m, oder aus dem β--Zerfall des Thorium-234 als Zwischenglied der Uran-Radium-Zerfallsreihe. Radioaktives Gleichgewicht von Uran-234. 1/100 ihres Anfangwertes beträgt. Auflage | Nils Wiberg, Egon Wiberg, Arnold Fr. The most stable is white pentoxide Pa2O5, which can be produced by igniting protactinium(V) hydroxide in air at a temperature of 500 °C. Similar to uranocene, it can be prepared by reacting protactinium tetrachloride with dipotassium cyclooctatetraenide, K2C8H8, in tetrahydrofuran. Die kritische Masse beträgt nach Angabe von Walter Seifritz 750±180 kg. [57] As with oxides, protactinium forms mixed halides with alkali metals. Protactinium er det 91. grundstof i det periodiske system, og har det kemiske symbol Pa: Under normale temperatur- og trykforhold optræder dette actinid som et sølvskinnende, radioaktivt metal. Immediate online access to all issues from 2019. [28][63], Protactinium is both toxic and highly radioactive and thus all manipulations with it are performed in a sealed glove box. Verschijning. Zum anderen wurde das Oxid zu den Halogeniden (Chlorid, Bromid oder Iodid) umgesetzt und diese dann im Vakuum an einem elektrisch beheizten Draht reduziert. 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) [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. matematiske faciliteter kan vi måle halveringstiden for Pa-234 selv, ved at lave nogle beregninger, og ændre … It is found in the form of two isotopes – 231Pa and 234Pa, with the isotope 234Pa occurring in two different energy states. Sein Analogon in der Reihe der Lanthanoide ist das Praseodym. [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. [57] The pentachloride melts at 300 °C and sublimates at even lower temperatures. 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 primary mode for the heavier isotopes (232Pa to 240Pa) is beta decay, producing isotopes of uranium. This isotope is 2.5×108 times more toxic than hydrocyanic acid. Die Zerfallskonstante . For example, 70% of the protactinium in the liver has a biological half-life of 10 days, and the remaining 30% for 60 days. Im Periodensystem steht es in der Gruppe der Actinoide (7. [64] The maximum allowed concentrations of 231Pa in the air in Germany is 3×10−4 Bq/m3. The protactinium-233 nuclide in turn decays through electron emission to yield uranium-233. Lehrbuch der Anorganischen Chemie, 102. Ich hoffe, dass ihr mir bei dieser Aufgabe helfen könnte, da ich es leider nicht verstehe. [35], Protactinium(V) chloride is prepared by reacting protactinium oxide with carbon tetrachloride at temperature of 200–300 °C. The hydride is obtained by direct action of hydrogen on the metal at 250 °C, and the nitride is a product of ammonia and protactinium tetrachloride or pentachloride. Grunnstoffet vart oppdaga av mellom anna Otto Hahn og Lise Meitner i 1913. Aber wie kann ein Elektron aus dem Kern kommen? [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$. ... Ausgangsnuklid der Uran-Radium-Reihe ist Uran-238. Protactinium er eit radioaktivt grunnstoff med kjemisk symbol Pa, atomnummer 91 og atommasse (231). [35], Protactinium bromides are produced by the action of aluminium bromide, hydrogen bromide, carbon tetrabromide or a mixture of hydrogen bromide and thionyl bromide on protactinium oxide. In a simplified scenario, lithium selectively reduces protactinium salts to protactinium metal which is then extracted from the molten-salt cycle, and bismuth is merely a carrier. Folosim cookie-uri pentru a personaliza conținutul, anunțurile și pentru a analiza traficul. Protactinium(V) fluoride and protactinium(V) chloride have a polymeric structure of monoclinic symmetry. Protactinium 231, ein Alphastrahler, entsteht beim Zerfall von 235U (siehe Uran-Actinium-Reihe), das betastrahlende Protactinium 234 beim Zerfall von Uran-238 (siehe Uran-Radium-Reihe). Protactinium 233Pa ist ein Zwischenprodukt im Brutprozess von Thorium 232Th zu Uran 233U in Thorium-Hochtemperaturreaktoren. 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. [18] Protactinium is homogeneously dispersed in most natural materials and in water, but at much lower concentrations on the order of one part per trillion, that corresponds to the radioactivity of 0.1 picocuries (pCi)/g. ekra > dek ekra a Þde certificat dekra dekra raÞd dekra kra iso 9001 :2015 dekra kra dekra ekra dekra dek dekra dekra ra de dekra ra>d kra dekr [28] In particular, its evaluation in oceanic sediments allowed to reconstruct the movements of North Atlantic water bodies during the last melting of Ice Age glaciers. [36] Protactinium is a metal with silvery-gray luster that is preserved for some time in air. In der Erde befindet sich das Isotop U-234. Die größte Menge an Protactinium wird künstlich erzeugt. [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. 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). The MPaF6 formula can be represented as a combination of MF and PaF5. 238 Uran Þ 234 Thorium Þ 234 Protactinium Þ 234 Uran Þ 230 Thorium Þ … These elements have 6, 5 and 4 valence electrons and thus favor +6, +5 and +4 oxidation states, respectively, and show different physical and chemical properties. 227Ac, in turn, decays into lighter isotopes with even shorter half-lives and much greater specific activities (SA), as summarized in the table below showing the decay chain of protactinium-231. [52][53] The pentoxide Pa2O5 combines with rare-earth metal oxides R2O3 to form various nonstoichiometric mixed-oxides, also of perovskite structure. Die Werte für die Eigenschaften (Infobox) sind, wenn nicht anders angegeben, aus. [59] Another organometallic complex is golden-yellow bis(π-cyclooctatetraene) protactinium, or protactinocene, Pa(C8H8)2, which is analogous in structure to uranocene. It forms various chemical compounds in which protactinium is usually present in the oxidation state +5, but it can also assume +4 and even +3 or +2 states. Periode, f-Block). Det som er fænomenet her er at, U-234 som har en yderst lang halveringstid på 4,47 mia. These compounds can be obtained by evaporating a hydrofluoric acid solution containing these both complexes. Besides, the concentration analysis for both protactinium-231 (half-life 32,760 years) and thorium-230 (half-life 75,380 years) allows to improve the accuracy compared to when only one isotope is measured; this double-isotope method is also weakly sensitive to inhomogeneities in the spatial distribution of the isotopes and to variations in their precipitation rate. 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. [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. [62] Some of the protactinium-related dating variations rely on the analysis of the relative concentrations for several long-living members of the uranium decay chain – uranium, protactinium, and thorium, for example. Only about 0.05% of ingested protactinium is absorbed into the blood and the remainder is excreted. Protactinium 234 .... etc. Radioaktivität (von französisch radioactivité; zu lateinisch radiare „strahlen“ und activus „tätig“, „wirksam“; zusammengesetzt also „Strahlungstätigkeit“) ist die Eigenschaft instabiler Atomkerne, spontan ionisierende Strahlung auszusenden. The thermal expansion, electrical and thermal conductivities of these three elements are comparable and are typical of post-transition metals. protactinium. Nowadays, it is mostly produced as an intermediate product of nuclear fission in thorium high-temperature reactors: The 231 isotope can be prepared by radiating thorium-230 with slow neutrons, converting it to the beta-decaying thorium-231, or by irradiating thorium-232 with fast neutrons, generating thorium-231 and 2 neutrons.