Protactinium (formerly protoactinium) is a chemical element with the symbol Pa and atomic number 91. Im Periodensystem steht es in der Gruppe der Actinoide (7. 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. Das Isotop von Uran-234 ist ein Mitglied der Uranreihe. [57] As with oxides, protactinium forms mixed halides with alkali metals. Die Bestimmung von Protactinium-233 Hildegard Pluskal Fresenius' Zeitschrift für analytische Chemie volume 162 , pages 127 – 128 ( 1958 ) Cite this article Dieses ist selbst radioaktiv und verwandelt sich innerhalb von 24 Tagen zur Hälfte in das Element Protactinium-234, welches noch rascher zerfällt. („zerfällt“). These compounds can be obtained by evaporating a hydrofluoric acid solution containing these both complexes. Ich hoffe, dass ihr mir bei dieser Aufgabe helfen könnte, da ich es leider nicht verstehe. The coordination is the same in protactinium(V) chloride, but the color is yellow. In all these organs, protactinium promotes cancer via its radioactivity. Die Quantenmechanik wird nicht nur von Schülern … Der Kern wandelt sich dabei unter Aussendung von Teilchen in einen anderen Kern um oder ändert unter Energieabgabe seinen Zustand. Alphazerfall - Lexikon der Physi . [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. Det som er fænomenet her er at, U-234 som har en yderst lang halveringstid på 4,47 mia. Cranston, Soddy, The parent of Actinium, Nature, Band 100, 1918, S. 498–499. [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. Protactinium 234 .... etc. Die von der Radioaktivität ausgehenden Gefahren gehören nicht zu den einzustufenden Eigenschaften nach der GHS-Kennzeichnung. [23] Im Jahre 1934 isolierte er erstmals elementares Protactinium aus 0,1 Milligramm Pa2O5. His method was still used in the 1950s to isolate 23490Th and 23491Pa from uranium compounds. It is found in the form of two isotopes – 231Pa and 234Pa, with the isotope 234Pa occurring in two different energy states. This bright yellow solid is stable to heating to 800 °C in vacuum. Eine kurze Beschreibung : Die Zahl vor dem Element steht für die Atommasse, gemessen in u. [60] However, the possibility of criticality of 231Pa has been ruled out since then. In Bezug auf weitere Gefahren wurde dieses Element entweder noch nicht eingestuft oder eine verlässliche und zitierfähige Quelle hierzu wurde noch nicht gefunden. [18][24] For many years, this was the world's only significant supply of protactinium, which was provided to various laboratories for scientific studies. [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. Protactinium 233Pa ist ein Zwischenprodukt im Brutprozess von Thorium 232Th zu Uran 233U in Thorium-Hochtemperaturreaktoren. 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. 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. The new name meant "(nuclear) precursor[5] of actinium" and reflected that actinium is a product of radioactive decay of protactinium. Aber wie kann ein Elektron aus dem Kern kommen? Dmitri Mendelejew postulierte im Jahre 1871 die Existenz eines Elements zwischen Thorium und Uran. 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. Im Periodensystem steht es in der Gruppe der Actinoide (7. Protactinium also has two nuclear isomers, 217mPa (half-life 1.2 milliseconds) and 234mPa (half-life 1.17 minutes). 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. år, kan henfalde til Pa-234 som har en halveringstid på kun 71 sekunder. [33], Protactinium is paramagnetic and no magnetic transitions are known for it at any temperature. [20], Aristid von Grosse produced 2 milligrams of Pa2O5 in 1927,[21] and in 1934 first isolated elemental protactinium from 0.1 milligrams of Pa2O5. 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. 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+. Boris F. Myasoedov, Harold W. Kirby, Ivan G. Tananaev: Diese Seite wurde zuletzt am 14. Heating the product to about 900 °C eliminates the reaction by-products such as hydrofluoric acid, sulfur trioxide and phosphoric anhydride. [31], Protactinium-233 is formed upon neutron capture by 232Th. Angol Főnév. Bij temperaturen onder 1,4 kelvin vertoont het supergeleidende eigenschappen. [13][14][15][16], Das langlebige 231Pa (t½ = 32.760 Jahre) wurde 1917 von Otto Hahn und Lise Meitner gefunden (veröffentlicht 1918), sie nannten es Protoactinium (von griechisch πρῶτος = protos: das Erste, der Vorhergehende, das chemische Element, das in der Zerfallsreihe des Uran-235 vor dem Actinium steht). 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. PaOBr3 has a monoclinic structure composed of double-chain units where protactinium has coordination 7 and is arranged into pentagonal bipyramids. [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$. In 1871, Dmitri Mendeleev predicted the existence of an element between thorium and uranium. In het mineraal uraniniet (pekblende) wordt protactinium in een concentratie van ongeveer 0,1 ppm aangetroffen. Beim Protactinium 234 besteht dabei eine Kernisomerie (di erente innere Zustände bei glei- cher Kernladungs- und Massenzahl), die zu zwei unterschiedlichen Halbwertszeiten führen. [64] The maximum allowed concentrations of 231Pa in the air in Germany is 3×10−4 Bq/m3. [12], 234mPa wurde 1913 von Kasimir Fajans und Oswald Helmuth Göhring entdeckt, sie gaben ihm wegen seiner kurzen Halbwertszeit (1,17 Minuten) den Namen Brevium (lateinisch brevis ‚kurz‘). Évaç onro- nugvwrÉÇ Y, Exnua öjar.popc- E,nirTÉða. [7] The actinide element group was unknown at the time. [10][11] Crookes löste Uranylnitrat in Ether, die verbleibende wässrige Phase enthielt größtenteils die Nuklide 234Th und 234Pa. [57] The pentachloride melts at 300 °C and sublimates at even lower temperatures. Hovudartikkelen for denne kategorien er Protactinium. und irgendwann zerfällt; Polonium 210 zu Blei 206 und Blei 206 ist stabil. Among those, most remarkable is Na3PaF8 where protactinium ion is symmetrically surrounded by 8 F− ions which form a nearly perfect cube. [35] The dioxide can be converted back to pentoxide by heating in oxygen-containing atmosphere to 1100 °C. In particular, 232Th via (n,2n) reactions produce 231Th which quickly (half-life 25.5 hours) decays to 231Pa. Aristid von Grosse isolierte im Jahre 1927 aus Abfällen der Radiumherstellung 2 Milligramm Protactinium(V)-oxid (Pa2O5). 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. Protactinium (Symbol Pa) ass e cheemescht Element mat der Uerdnungszuel 91 am Periodesystem vun den Elementer. [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. 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. The estimated shear modulus of protactinium is similar to that of titanium. Die folgenden Elemente sind Thorium, Protactinium, Uran und Thorium in dieser Reihenfolge. 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). [48], Protactinium(V) fluoride forms white crystals where protactinium ions are arranged in pentagonal bipyramids and coordinated by 7 other ions. Sein Analogon in der Reihe der Lanthanoide ist das Praseodym. Die Zerfallsreihe von Uran-238 bis Blei-206: 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- 234 245'500 Jahren zu Thorium-230 75'400 Jahren zu. Schlauerfuchs ... Berechne die Zerfallskonstante "lambda" und die Halbwertszeit. In another method, called the van Arkel–de Boer process, the oxide was chemically converted to a halide (chloride, bromide or iodide) and then reduced in a vacuum with an electrically heated metallic filament:[18][23], In 1961, the United Kingdom Atomic Energy Authority (UKAEA) produced 127 grams of 99.9% pure protactinium-231 by processing 60 tonnes of waste material in a 12-stage process, at a cost of about US$500,000. Kategori:Protactinium. There is about 500 times more protactinium in sandy soil particles than in water, even the water present in the same sample of soil. The corresponding values for kidneys are 20% (10 days) and 80% (60 days). Bemerkungen: Uran-234 (historisch: Uran II, U II) wird durch β--Zerfall von Protactinium-234 als Zwischenglied der Uran-Radium-Reihe gebildet. 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. Anmerkung zur Spontanspaltung: Die Daten werden unter der Annahme berechnet, dass Tochterkerne mit 61 % bzw. Another phase of this oxide with orthorhombic symmetry has also been reported. [28][63], Protactinium is both toxic and highly radioactive and thus all manipulations with it are performed in a sealed glove box. The MPaF6 formula can be represented as a combination of MF and PaF5. 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. 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. Protactinium metal can be prepared by reduction of its fluoride with calcium,[33] lithium or barium at a temperature of 1300–1400 °C. [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. Dazu wurde jeweils eine Spatelspitze des Metalls bzw. The chains are interconnected through oxygen and bromine atoms, and each oxygen atom is related to three protactinium atoms. 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. [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. Protactinium oxides are known for the metal oxidation states +2, +4 and +5. Wegen seiner Seltenheit, hohen Radioaktivität und Giftigkeit findet Protactinium außer in der Forschung keine praktische Anwendung. [35], Protactinium forms mixed binary oxides with various metals. 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. For ease of pronunciation, the name was shortened to protactinium by IUPAC in 1949. Man weiß, dass bei diesem ß-Zerfall Protactinium 234 mit 91 Protonen entsteht. [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. in Jáchymov, Czech Republic[29]), some ores from the Democratic Republic of the Congo have about 3 ppm. Ist mein Wert nun komplett falsch, geschweige denn meine Rechnungen, oder sind es die Werte, die mich zu einem solchen Ergebnis geführt haben? Im Periodensystem steht das Protactinium mit der Ordnungszahl 91 in der Reihe der Actinoide, sein Vorgänger ist das Thorium, das nachfolgende Element ist das Uran. 1/100 ihres Anfangwertes beträgt. [26], Später stellte er auch metallisches Protactinium aus Protactinium(V)-iodid (PaI5) dar. Nearly all natural protactinium is protactinium-231. 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. auf Blei wurde versucht, das Protactinium auf Mangan- AM = Zerfallskonstante der hluttersubstanz (=Th) Granalien [I] und Mangandiox~d (Merck-Ragens P- = Zerfallskonstante der Tochtersubstanz (234mPa) abzuscheiden. b) Berechnen Sie die Zählrate nach 6min. These compounds easily hydrolyze in water. Radioaktives Gleichgewicht von Uran-234. [59] Another organometallic complex is golden-yellow bis(π-cyclooctatetraene) protactinium, or protactinocene, Pa(C8H8)2, which is analogous in structure to uranocene. Heating the nitrate in air at 400 °C converts it to the white protactinium pentoxide. Protactinium (formerly protoactinium) is a chemical element with the symbol Pa and atomic number 91. Th234 besitzt 90 Protonen und 144 Neutronen. protactinium. 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. [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. [7] Oak Ridge National Laboratory in the US provided protactinium at a cost of about US$280/gram. De product pagina's zijn in Engels, maar brochures en gebruiksaanwijzingen kunt u ook in het Nederlands downloaden. Für den ß-Zerfall betrachten das Thorium-Isotop mit 234 Nukleonen. [35] Protactinium forms borohydrides which include Pa(BH4)4. Ugrás a navigációhoz Ugrás a kereséshez. [45] PaOS is a light-yellow non-volatile solid with a cubic crystal lattice isostructural to that of other actinide oxysulfides. În cazul în care alegeți să continuați să utilizați website-ul nostru, sunteți de acord cu utilizarea modulelor noastre cookie. [9] Für lange Zeit suchten Chemiker nach Eka-Tantal mit ähnlichen chemischen Eigenschaften zum Tantal. Die Werte für die Eigenschaften (Infobox) sind, wenn nicht anders angegeben, aus. [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"). 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. Protactinium(V)-oxid (Pa2O5) ist ein weißes, kristallines Pulver. [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. Other articles where Protactinium-233 is discussed: nuclear reactor: Fissile and fertile materials: …decays through electron emission to protactinium-233, whose half-life is 26.967 days. 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 ). [32] 233Pa has a relatively long half-life of 27 days and high cross section for neutron capture (the so-called "neutron poison"). The structure changes to face-centered cubic (fcc) upon cooling from high temperature, at about 1200 °C. 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. protactinium-234. Am Ende dieser so genannten Zerfallsreihe steht das stabile Blei-206. [26], Protactinium is one of the rarest and most expensive naturally occurring elements. [42], Oxyhalides and oxysulfides of protactinium are known. The protactinium-233 nuclide in turn decays through electron emission to yield uranium-233. Density was not measured directly but calculated from the lattice parameters. [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. Subscription will auto renew annually. b) -zuerst rechnete ich um: 6min sind 360s Vha. Heating to higher temperatures in an inert atmosphere decomposes Pa(PO3)4 into the diphosphate PaP2O7, which is analogous to diphosphates of other actinides. Radioaktives Gleichgewicht von Uran-234. It is not readily soluble in either dilute or concentrated nitric, hydrochloric or sulfuric acids, but easily dissolves in hydrofluoric acid. In all these materials, protactinium ions are octahedrally coordinated. So, nun habe ich aber bei einer anderen Seite gesehen, dass die Halbwertszeit von Protactinium 71s beträgt. [26], The primary decay mode for the most stable isotope 231Pa and lighter (211Pa to 231Pa) is alpha decay, producing isotopes of actinium. This antibody recognizes a 66 kDa protein, which is identified as Tripartite motif-containing protein 29 (TRIM29). [54], Protactinium oxides are basic; they easily convert to hydroxides and can form various salts, such as sulfates, phosphates, nitrates, etc. As the electron configuration of the neutral atom is [Rn]5f26d17s2, the +5 oxidation state corresponds to the low-energy (and thus favored) 5f0 configuration. Much smaller trace amounts of the short-lived protactinium-234 and its nuclear isomer protactinium-234m occur in the decay chain of uranium-238. [45][47], Protactinium iodides result from the oxides and aluminium iodide or ammonium iodide heated to 600 °C. Die Zerfallskonstante . 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.