Radioactive decomposition

See the clear exposition given the process of radioactive decomposition by M. Born, Zeits. f. Physik 58, 306 (1929). 

The science of kinetics deals with the mathematical description of the rate of the appearance or disappearance of a substance. One of the most common types of rate processes observed in nature is the first-order process in which the rate is dependent upon the concentration or amount of only one component. An example of such a process is radioactive decay in which the rate of decay (i.e., the number of radioactive decompositions per minute) is directly proportional to the amount of undecayed substance remaining. This may be written mathematically as follows ... 

Radioactive decomposition of labile elements (such as uranium, thorium or... 

It is now accepted as a proved fact that the element radium decomposes with the formation of other elements, the simplest of which is apparently helium, and the experiments of Sir William Ramsay have indicated that the energy liberated by radium can effect the transmutation of other elements into one another but in such cases man can only watch the changes that go on, and cannot control or vary them. But in the building-up process that has apparently now been discovered, the energy for the change is artificially supplied and controlled, and the changes are thus of a different order from the radioactive decompositions of a decaying element. 

Radioactive decompositions are first order reactions. The specific rate in this discipline is called the decay constant,... 

Uranium is a while metal, ductile, malleable, and capable of taking a high polish, but tarnishes readily on exposure to the atmosphere. Finely divided uranium burns upon exposure to air, and the compact metal burns when heated in air at 170 0 Uranium metal slowly decomposes water at ordinary temperatures and rapidly at 100 0 is soluble in HC1 and in HN03 and is nnattacked by alkalis. Chemically related to chromium, molybdenum, and tungsten and, like thorium, is radioactive. In the radioactive decomposition radium is formed. Discovered by Klaproth in 1789. 

The nucleus is stable, so that this nuclear reaction does not lead to the production of artificial radioactivity. Many other eleuicnts, hotsever, undergo similar reactions with the production of unstable nuclei, which then undergo radioactive decomposition. 

During and since World War II some quantity of the isotope Pu has been manufactured. This isotope is relatively stable it has a half-life of about 24,000 years. It slowly decomposes with the emission of alpha particles. It is made by the reaction of the principal isotope of uranium, U- , with a neutron, to form which then undergoes spontaneous radioactive decomposition with emission of an electron to form Np , which in turn emits an electron spontaneously, forming... 

This isotope slowly undergoes radioactive decomposition, with emission of alpha particles. Its half-life is 500 years. Curium is made from... 

We have summarized in the previous pages the recent developments (prior to 1980 ) of new soft ionization techniques and of various peripherals. These aspects often responded to the need to obtain molecular ions, in order to determine the molecular masses of these often thermo-labile biological molecules, leading to the development of soft ionization methods and to obtain sufficient vaporization (or desorption) of the sample studied. Among other methods, field desorption (and DCI), the use of lasers and radioactive decomposition of Cf have been introduced. 

In the following three sections we shall discuss four applications of quantum mechanics to miscellaneous problems, selected from the very large number of applications which have been made. These are the van der Waals attraction between molecules (Sec. 47), the symmetry properties of molecular wave functions (Sec. 48), statistical quantum mechanics, including the theory of the dielectric constant of a diatomic dipole gas (Sec. 49), and the energy of activation of chemical reactions (Sec. 50). With reluctance we omit mention of many other important applications, such as to the theories of the radioactive decomposition of nuclei, the structure of metals, the diffraction of electrons by gas molecules and crystals, electrode reactions in electrolysis, and heterogeneous catalysis. 

Ishikawa et al. (1976) investigated the persistence and degradation of radiolabelled benthiocarb in sandy clay loam soil. Twenty radioactive decomposition products were detected, the major products being desethyl benthiocarb, benthiocarb sulfoxide, 3-chlorobenzoic acid, 2-hydroxybenthiocarb and 4-chIoro-benzylmethyl sulfon, while 4-chlorobenzylmethyl sulfoxide and 4-chlorobenzyl alcohol were detected in small amounts. 

The most important class of first-order reactions is the radioactive decomposition of atomic nuclei. Each nucleus of radium 226 or other radio-nucleide has a probability of decomposition in unit time that is independent of the concentration (in general, of the presence of other particles), and in consequence the process of radioactive decay is represented by Equations 10-1 and 10-4. 

The symbol used for the photon is y (the Greek letter gamma). This symbol was originally used for y-rays, which are photons of high energy liberated in the course of the radioactive decomposition of nuclei. 

In 1934 Fermi developed his theory of /3 decay, in order to explain the puzzling observation that some radioactive nucleides shoot out an electron in the course of radioactive decomposition, although they were supposed to be composed only of protons and neutrons. He pointed out that atoms emit photons when they change from one quantum state to another, although it is not believed that the atoms contain the photons instead, it is accepted that the photon is created at the time when it is emitted. Fermi suggested that the electrons, the (3 particles, are created when the radioactive nucleus undergoes decomposition, and that at the same time one of the neutrons inside the nucleus becomes a proton, and a neutrino (or, rather, an antineutrino) is emitted. 

The following radioactive decompositions are examples of the different ways in which an unstable nucleus can decompose ... 

RADIOTOXICITY The potential of an isotope to cause damage to living tissue by the depositing of the energy of the radioactive decomposition into that tissue. 

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