Radioactive decay series, natural

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. 

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. 

Uranium-238 is the parent of a natural radioactive decay series that can be used to determine the ages of rocks. 

Table 2.1 The natural radioactive decay series from to 82Pb (see Figure 2.3) (yr = year d = day min = minute s = second).

Because all long natural radioactive decay series end up in lead, Pb made from different ores contain slightly different isotopic abundances of lead isotopes. An imusual use of this fact was made by Andrasko et. al. to identify smears and fragments from lead bullets used in a homicide case, so that the suspect could be bound to the case, as the isotopic composition of lead bullets can be identified not only by manufacturer but also by manufacturing date. 

We use X to indicate any element defined by its nuclear charge, Z and Z-2 in this equation. Examples are given in Ch. 1, and can be found e.g. in the natural radioactive decay series, see next chapter. 

As the detection technique for radioactivity has been refined, a number of long-lived radionuclides have been discovered in nature. The lightest have been motioned in 5.1. The heavier ones, not belonging to the natural radioactive decay series of uranium and thorium, are listed in Table 5.2. is the nuclide of lowest elemental specific activity ( 0.(XX)1 Bq/g) while the highest are Rb and Re (each —900 Bq/g). As our ability to make reliable measurements of low activities increases, the number of elem ts between potassium and lead with radioactive isotopes in nature can be expected to increase. 

In addition to stable elements, radioactive elements are also produced in stars. There are four natural radioactive decay series Th (Ti/2 = 1.405 10 yr),... 

Details of the natural radioactive decay series are particularly important for several radioactive dating methods (O Chap. 17 of this Volume). These methods depend on differences in chemical properties of chain components in a geological environment and ongrowth-and-decay among the components. See Chap. 7 in Vol. 1. 

Uranium-238 is the parent of a natural radioactive decay series. 

Table 22-4 Emissions and Half-Lives of the Natural Radioactive Decay Series ...

Radioactive nuclei emit a particles, 13 particles, positrons, or y rays. The equation for a nuclear reaction includes the particles emitted, and both the mass numbers and the atomic numbers must balance. Uranium-238 is the parent of a natural radioactive decay series. A number of radioactive isotopes, such as and C, can be used to date objects. Artificially radioactive elements are created by the bombardment of other elements by accelerated neutrons, protons, or a particles. Nuclear fission is the splitting of a large nucleus into smaller nuclei plus neutrons. When these neutrons are captured efficiently by other nuclei, an uncontrollable chain reaction can occur. Nuclear reactors use the heat... 

FIGURE 8-2 A natural radioactive decay series. Alpha decay is shown by arrows that go down and to the left. Beta decay is shown by arrows to the right. The half-life is shown for each decay process. 

Tables 1-3 give the members, half-lives, decay constants and modes of decay of the natural radioactive decay series of U, and Th, respectively.

Natural Radioactive Decay Series—Nuclear Equations... 

The two disintegrations described in Equations 20.2 and 20.3 are only the first two of 14 steps that begin with 23 u. There are eight a-particle emissions and six /3-particle emissions, leading ultimately to a stable isotope of lead, 2° Pb. This entire natural radioactive decay series is described in Figure 20.11. There are two other natural disintegration series. One begins with 2 Th and ends with 2° Pb, and the other passes from 23 u to Pb. 

In addition to the natural radioactive decay series that begins with U-238 and ends with Pb-206, there are natural radioactive decay series that begin with U-235 and Th-232. Both of these series end with nuchdes of Pb. Predict the likely end product of each series and the number of a decay steps that occur. 

The natural radioactive decay series for 9 U (uranium series)... 

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