Disintegration series

A radioactive element may be designated as being in a collateral senes. In addition to the three main natural and one artificial disintegration series of radioactive elements, each has been round to have at least one parallel or collateral series. The main series and the collateral series have different parents, but become identical in the course of disintegration, when they have a member in common. 

Radioactive Disintegration Series The series of spontaneous changes that take place starting from the parent element (which has unstable nucleus) till the formation of an element with stable nucleus is called... 

The slowest step in any of the disintegration series generally determines the time in which half of the original parent is converted to the final, stable product. Eor example, if we add up the half-lives of all the isotopes in Figure 21.1a, we get a sum equal to the half-life of within the rules of significant digits. 

Create a graph for the disintegration series that starts with like that for in Figure 21.1b. 

Which of the four disintegration series disintegrates to the final stable isotope with a half-hfe different from the half-life of its original parent isotope (with due regard to significant digits) ... 

The following scheme represents the uranium disintegration series according to the present state of knowledge ... 

From the position of ionium in the disintegration series, its atomic weight should be approximately 230. Honigsehmid found 231-5 for thorium-ionium mixtures obtained from minerals poor in thorium. 

The properties of the elements of the uranium disintegration series are summarised in the accompanying table. 

There is no difference between the principles governing natural and artificial radioactivity. The classical disintegration series stem from radionuclides with long half-lives, exceeding 10 years. Their decay is almost entirely by a- and /9-emissions. 

Nuclei with Atomic Number Greater Than 83 Detection of Radiation Rates of Decay and Half-Life Disintegration Series Uses of Radionuclides Artificial Transmutations of Elements Nuclear Fission Nuclear Fission Reactors Nuclear Fusion... 

While studying radioactivity it was found thit hd obtained from the disintegration series of uranium hjs... 

Three isotopes of lead are the end products of the three natural disintegration series just considered. As these are inactive they accumulate in their radioactive mineral sources. 

FIGURE 21.3 Nuclear disintegration series for uranium-238. The decay... 

Some nuclei cannot gain stability by a single emission. Consequently, a series of successive emissions occurs as shown for uranium-238 in A FIGURE 21.3. Decay continues until a stable nucleus—lead-206 in this case—is formed. A series of nuclear reactions that begins with an unstable nucleus and terminates with a stable one is known as a radioactive series or a nuclear disintegration series. Three such series occur in nature uranium-238 to lead-206, uranium-235 to lead-207, and thorium-232 to lead-208. 

Radon-222 is a product of the nuclear disintegration series of uranium-238 (Figure 21.3) and is continuously generated as uranium in rocks and soil decays. As Figure 21.25 indicates, radon exposure is estimated to account for more than half the 360-mrem average annual exposure to ionizing radiation. 

SECTION 21.2 The neutron-to-proton ratio is an important factor determining nuclear stability. By comparing a nuclide s neutron-to-proton ratio with those in the band of stability, we can predict the mode of radioactive decay. In general, neutron-rich nuclei tend to emit beta particles proton-rich nuclei tend to either emit positrons or im-dergo electron capture and heavy nuclei tend to emit alpha particles. The presence of magic numbers of nucleons and an even number of protons and neutrons also help determine the stability of a nucleus. A nuclide may undergo a series of decay steps before a stable nuclide forms. This series of steps is called a radioactive series or a nuciear disintegration series. 

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