Actinium 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. 

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) ... 

In the first steps of its radioactive decay series, thorium-232 decays to radium-228, which then decays to actinium-228. What are the balanced nuclear equations describing these first two decay steps ... 

FlC- 1-2, The three naturally occurring radioactive decay series and the man-made neptunium series. Although (which is the parent to the actinium series) and (which is the parent to the thorium series) have been discovered in nature, die decay series shown here begin with the most abundant Icmg-Uved nuclides. 

The exponential laws of radioactive-series decay and growth of radionuclides were first formulated by Rutherford and Soddy in 1902, to explain their results (Rutherford and Soddy 1902,1903) on the thorium series of radionuclides. In 1910, Bateman (Bateman 1910) derived generalized mathematical expressions that were used to describe the decay and growth of the naturally occurring actinium, uranium, and thorium series until the discovery of nuclear fission and other new radioactive decay series were found in the 1940s. For the description of half-lives and decay constants, activities and number of radionuclides involved in the decay of two radionuclides, Friedlander et al. (1981) have given a representative overview (see also O Chap. 5 in Vol. 1). 

The chain of radioactive decay that begins with continues through a number of steps of a and j8 emission until it eventually terminates with a stable isotope of lead— 82 1. The entire scheme is outlin in Figure 25-2. All naturally occurring radioactive nuclides of high atomic number belong to one of three radioactive decay series the uranium series just described, the thorium series, or the actinium series. (The actinium series actually begins with uranium-235, which was once called actino-uranium.)... 

Various radium isotopes are derived through a series of radioactive decay processes. For example, Ra-223 is derived from the decay of actinium. Ra-228 and Ra-224 are the result of the series of thorium decays, and Ra-226 is a result of the decay of the uranium series. 

One of the most important observations of atoms is the set of relationships between elements that belong to one of the series of radioactive decays. The parent elements of uranium, thorium and actinium decay through many intermediates to the stable element lead. The Nobel Prize in Chemistry for 1921 was awarded in 1922 to Frederick Soddy for his complete characterization of these processes. The story is beautifully told in his Nobel Lecture entitled The origins of the conception of isotopes (25). 

I he atomic wcighi varies because of natural variations in the isotopic composition of the element, caused by the various isotopes having different origins - I h is the end product of the thorium decay scries, while Ph and " Pb arise Irom uranium as end products of the actinium and radium series respectively. Lead-204 has no existing natural radioactive precursors. Electronic configuration l.v 2s lfc22/j"3v 3//,3i/l"4v- 4/, 4l/" 4/ IJ5v- 5/ "5t/l"bv />-. Ionic radius Pb I.IX A. Pb 1 0.7(1 A. Metallic radius 1.7502 A. Covalent radius (ip i 1.44 A. First ionization potential 7.415 cV second. 14.17 eV. Oxidation... 

PROTACTINIUM. [CAS 7440-13-13], Chemical element, symbol Pa, at. no. 91, at. wt, 231.036, radioactive metal of the Actinide Series, mp is estimated at less than 1600°C, All isotopes arc radioactive. The most stable isotope is 23IPa with a half-life of 3,43 v 104 years, The latter is a second-generation daughter of a5U and a member of the actinium (2n + 3) decay series, See also Radioactivity, Electronic configuration... 

The radioactive decay of produces stable lead-207 after the emissions of seven a particles and four P particles and constitutes the actinium series (A = 4n+3). The process may be represented as... 

This analysis can, for example, be applied to multistep radioactive decay reactions and to isomerization reactions. In such multistep processes, every step is by definition a first-order process. An example of multistep radioactive decay is the Actinium series (see Lederer et ah, 1968), in which Bi alpha-decays to ° T1, which beta-decays to ° Pb with respective half-lives of 2.14 and 4.77 min. Therefore, in this two-step consecutive process, k J ki =/9 = 2.14/4.77 = 0.449, very close to the Acme point. Similarly, in the Radium series, Pb beta-decays to which beta-decays to Po, which then alpha-decays very rapidly (with a half-life of only 0.16 ms) to ° Pb. This multistep decay can be closely approximated by two steps, the first with a half-life of 27 min, the second with a half-life... 

Once it became clear that radioactive elements were decaying to new elements, which were themselves radioactive, a great deal of effort was expended in working out the decay sequences. In most cases the new elements were at first obtained in quantities too small to be weighed and were distinguished from each other only by the type of decay they exhibited and the rate at which the decay occurred. Three decay series were elucidated the uranium series proceeded through radium and terminated with the stable radium G the thorium series ended in the stable thorium D and the actinium series ended in actinium D. Between them, these series contained around 25 new radioelements. 

Other natural decay series originate with thorium and actinium. Radon is also an intermediate link in the former, the radioactive thorium decay series ... 

Two methods to secure very small samples of francium for examination use the decay processes of other radioactive elements. One is to bombard thorium with protons. The second is to start with radium in an accelerator, where, through a series of decay processes, the radium is converted to actinium, which in turn rapidly decays into thorium, and finally, thorium decays naturally into francium. Following is a schematic of the decay process used for the production of small amounts of Fr-223 which, in turn, after several more decay processes ends up as stable lead (Pb) ... 

Actinium decays via a series of short-lived isotopes, eventually ending with stable lead. The presence of these radioactive daughters, particularly Th (which is a strong y-emitter), necessitates the use of lead-lined gloved boxes and remote control manipulators. Consequently, the metallurgy of actinium has been little studied and, due to the great expense and trouble involved, probably will not be studied extensively in the future. 

ACTINON. The name of the isotope of radon (emanation), which occurs in the naturally occurring actinium, series being, produced by alpha-decay of actinium X, which is itself a radium isotope. Achnon has an atomic number of 86, a mass number of 219, and a half-life of 3.92 seconds, emitting an alpha particle to form polonium-215 (Actinium A). See also Chemical Elements and Radioactivity. 

Radiation Hazard Natural isotope (Actinium-X, Actinium Series), Tl/2 = 11.4 days, decays to radioactive by alphas of... 

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