Protactinium occurrence

The occurrence of fission in uranium is due to the presence of 2llU, which makes up only 0.07% of natural uranium. Other elements including thorium, protactinium, neptunium, and plutonium are also capable of undergoing fission, and fission may be induced not only by neutrons but also by protons, deutrons, alpha particles, and even gamma rays. 

The terrestrial occurrence of Ac, Pa, U, and Th is due to the half-lives of the isotopes 235U, 238U and 232Th which are sufficiently long to have enabled the species to persist since genesis. They are the sources of actinium and protactinium formed in the decay series and found in uranium and thorium ores. The half-lives of the most stable isotopes of the trans-uranium elements are such that any primordial amounts of these elements appear to have disappeared long ago. However, neptunium and plutonium have been isolated in traces from uranium13 minerals in which they are formed continuously by neutron reactions such as... 

Propionohydroxamic acid metal complexes, 506 Propylenediamine metal complexes, 34 Protactinium complexes cupferron, 510 Proteins electron transfer active sites, 525 metal complexes, 759-774 binding sites, 769,771 naturally occurring, 974 occurrence, 962 Proton exchange amine ligands, 24 Protonolysis metal alkoxides, 352 Prussian blue, 7, 8 Pseudocubanes structure... 

Protactinium see also Elements electrical resistivity, 12-39 to 40 electron configuration, 1-18 to 19 heat capacity, 4-135 history, occurrence, uses, 4-1 to 42 ionization energy, 10-203 to 205 isotopes and their properties, 11-56 to 253 magnetic susceptibility, 4-142 to 147 physical properties, 4-133 to 134 thermal properties, 12-201 to 202 vapor pressure, high temperature, 4-136 to 137... 

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See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

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