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Protactinium-231 is the longest-lived isotope of protactinium, with a half-life of 32,760 years. In nature, it is found in trace amounts as part of the actinium series, which starts with the primordial isotope uranium-235; the equilibrium concentration in uranium ore is 46.55 231 Pa per million 235 U.
Nearly all natural protactinium is protactinium-231. It is an alpha emitter and is formed by the decay of uranium-235, whereas the beta radiating protactinium-234 is produced as a result of uranium-238 decay. Nearly all uranium-238 (99.8%) decays first to the shorter-lived 234m Pa isomer. [37]
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 ...
Pages in category "Isotopes of protactinium" ... Protactinium-235; Protactinium-236; Protactinium-237; Protactinium-238; Protactinium-239; Protactinium-240 ...
protactinium-223: 5.1 americium-223: 5.2 sodium-34: 5.5 lead-205m2: 5.55 neptunium-225: 6 uranium-218: 6 radon-195: 6 radon-195m: 6 carbon-22: 6.2 meitnerium-270: 6.3 rutherfordium-256: 6.4 bismuth-184: 6.6 thorium-209: 7 protactinium-213: 7 seaborgium-262: 7 neon-30: 7.3 protactinium-212: 8 sodium-33: 8 magnesium-37: 8 livermorium-290: 8.3 ...
Protactinium is more abundant (10 −12 %) in the Earth's crust than actinium. It was discovered in uranium ore in 1913 by Fajans and Göhring. [34] As actinium, the distribution of protactinium follows that of 235 U. [61] The half-life of the longest-lived isotope of neptunium, 237 Np, is negligible compared to the age of the Earth.
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The actinide series is a group of chemical elements with atomic numbers ranging from 89 to 102, [note 1] including notable elements such as uranium and plutonium.The nuclides (or isotopes) thorium-232, uranium-235, and uranium-238 occur primordially, while trace quantities of actinium, protactinium, neptunium, and plutonium exist as a result of radioactive decay and (in the case of neptunium ...