Decay series, radioactive

Atoms with Z 83 are radioactive and decay in one or more steps involving primarily alpha and beta decay (with some gamma decay to carry away excess energy). For example, uranium (atomic number 92) is the heaviest naturally occurring element. Its most common isotope is U-238, an alpha emitter that decays to Th-234. 

A fikn-badge dosimeter consists of a piece of photographic fihn in a light-resistant container. The film s exposure in a given time is proportional to the amount of radiation it receives. 

Probably the most important chain reactions in geochemistry are the decay series 

Three decay chains are shown in Table 2-2, with all the reaction steps and the decay constants (rate coefficients). The decay chain of is used as an example for detailed discussion below. The U-series is a long and complicated decay chain starting from after 8 a-decays and 6 p-decays (in places there are different branches and paths), the final stable product is ° Pb. 

Every decay reaction in each decay chain is a first-order elementary reaction. To solve the concentration of each species in the decay series, the reaction rate laws for every species (ignoring the minor effect of different states of Pa) are written below  

The steps from to are 8 a-decays and 6 P-decays. The net reaction is - 206pb ( 3jg fjom Lockheed Martin (2002) and Firestone and Shirley (1996). The nuclide in 

The above set of differential equations (20 equations) can be solved with the help of linear algebra (matrix operation). Even though the math is not particularly  

In nature, the radioisotopes and each begin a cascade of daughter products referred 

Actinides and Their Daughter and Fission Products Chap. 13 

This simplification arises from the fact that, in most cases, the ultimate parents and Th) 

In the Th decay series there is a significant branch in the series at Bi, which undergoes either a- or -decay. The half-lives of the two decay modes of Bi both are given as 1.15 x 1y. This is the cumulative half-life of both types of decay. The other two decay series have minor branches O ss than 1% branch in all but one case), and are shown in simplified form in Table 13.2. 

The rate law given in Eq. (13.1) for simple one-step radioactive decay does not hold for decay series. I ecay series can be represented schematically as in Fig. 13.2 and in the form of a series of chemical reactions as 

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Polonium, completing the elements of Group 16, is radioactive and one of the rarest naturally occurring elements (about 3 x 10 " % of the Earth s crust). The main natural source of polonium is uranium ores, which contain about lO g of Po per ton. The isotope 210-Po, occurring in uranium (and also thorium) minerals as an intermediate in the radioactive decay series, was discovered by M. S. Curie in 1898. 

Natural lead, a metallic element, is a mixture of the following four isotopes lead-204, lead-206, lead-207, and lead-208. Only lead-204 is a primordial isotope of nonradiogenic origin all the others are radiogenic, each isotope being the end product of one of the radioactive decay series of isotopes of thorium or uranium, namely, uranium-238, uranium-235, and thorium-232 the decay series of the uranium isotopes are listed in Figure 12 ... 

The Development of Modern Chemistry. Harper and Row, New York, 1964, xii + 851 pp. including illustrations, Appendixes, (Discovery of the Elements, Discovery of Natural Radioactive Isotopes, Radioactive Decay Series, Nobel Prize Winners in Chemistry, Physics, and Medicine), and Bibliographic Notes. 

As already noted, while it is the intention for the rest of this chapter to give references to original literature, this will not be done for the (extensive) literature on studies of radioactive decay series which preceded the publication of the historic papers of Soddy and Fajans in 1913. This material was well reviewed by F. Soddy (NLC 1921 ) in his Nobel Lecture which is used as the sole reference here (Soddy 1922). 

Fig. 1.2 The three natural radioactive decay series as understood by F. Soddy and K. Fajans in the period 1913-1920...

The stage was now set for the 1913 papers published independently by Fajans (1913b) and by Soddy (1913a). The paper by Fajans was published a couple of weeks prior to that by Soddy. Soddy has stated that he had not seen the Fajans paper at the time when he wrote his paper. Both papers try to generalize experimental observations on the chemical identities of decay products in the three natural radioactive decay series. 

ISOTOPES There are 41 isotopes of polonium. They range from Po-188 to Po-219. All of them are radioactive with half-lives ranging from a few milliseconds to 102 years, the latter for its most stable isotope Po-209. Polonium is involved with several radioactive decay series, including the actinium series, Po-211 and Po-215 the thorium series, Po-212 and Po-216 and the uranium decay series, Po-210, Po-214, and Po-218. 

In treating the radioactive decay series of U, we explored the concepts of ratedetermining step and steady state, and learned how they are applied to treat... 

Radioactive decay series may be viewed as chain reactions. Section 2.2.1 summarized the three decay series series, series, and Th series. In the... 

An unstable parent nucleus may decay into either a stable or an unstable daughter. When the daughter is unstable, which is often the case, the daughter will decay. Often the journey from an unstable nucleus to a stable nucleus involves a long series of steps referred to as a radioactive decay series. One example is the decay series for radium (Figure 17.2). 

A suitable radioactive decay series in which both a and emission occur within a reasonable time is found in the heavier actinides where ... 

Daughters of alpha emitters The recoil method can also be useful for the separation of daughter products produced by a decay of a parent. This technique has been applied to studies of short-lived daughters In the radioactive decay series of uranium, thorium, and actinium (175) ... 

The element francium is formed in the natural radioactive decay series and in nuclear reactions. All its isotopes are radioactive with short half-lives. The ion behaves as would be expected from its position in the group. 

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