Uranium disintegration series

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

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

The uranium disintegration series. iU decays by a series of alpha (a) and beta (p) emissions to the stable nuclide Pb. 

The series of Radioactive disintegrations the uranium-radium series, the uranium-actinium series, the thorium series, and the neptunium series. The age of the earth. The fundamental particles electron, proton, positron, neutron, positive, negative, and neutral mesons, neutrino. The photon (light quantum) the energy of a photon, hv. Planck s constant. The wave-particle duality of light and of matter. The wavelengths of electrons. 

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

The disintegration of a radioactive nucleus is often the beginning of a radioactive decay series, which is a sequence of nuclear reactions that ultimately result in the formation of a stable isotope. Table 23.3 shows the decay series of naturally occurring uranium-238, which involves 14 steps. This decay scheme, known as the uranium decay series, also shows the half-lives of all the products. 

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. 

M Figure 21.4 Nuclear disintegration series for uranium-238. The nucleus decays to oTh. Subsequent decay processes eventually form the stable gfPb nucleus. Each blue arrow corresponds to the loss of an alpha particle each red arrow corresponds to the loss of a beta particle. 

A few such series are known to occur in nature. Two begin with isotopes of uranium, and and one begins with Th. All three of these end with a stable isotope of lead (Z = 82). Table 22-4 outlines in detail the and Th disintegration series,... 

Other short-lived isotopes can, however, still be detected in nature. The element number 86, radon (Rn), has several isotopes, the most long-lived of which has a half-life of only 3.8 days. How is it then possible that we have radon problems in our mines and our houses The answer is that radon certainly disintegrates rapidly but is also being formed continuously. Radon is part of the radioactive uranium decay series ... 

Write the nuclear equation for the changes that occur in the uranium-238 disintegration series when gfRa ejects an a-particle. Ra is the symbol for radium, one of the elements discovered by Pierre and Marie Curie in their study of radioactivity. 

When thorium emits alpha particles, it disintegrates into other daughter radionuclides (radioactive materials), such as radium-226 and radon-222 (from thorium-230 in the uranium-238 decay series) or radium-228 and thoron (radon-220 from thorium-232 in the thorium decay series). It eventually decays to stable lead-208 or -206, which is not radioactive. More information about the decay of thorium can be found in Chapter 3. The toxicological characteristics of radon, radium, and lead are the subject of separate ATSDR Toxicological profiles. 

There is also a sixth member of this series, known as uranium Y (46, 50, 56, 59), which was discovered in 1911 by G. N. Antonoff, who was working under Sir Ernest Rutherford at the University of Manchester. He afterward returned to St. Petersburg. Uranium Y, like uranium Z, belongs to a subordinate branch of the family. Frederick Soddy attributed Antonoff s success, not to the special chemical process adopted, but to the lapse of a suitable period of time between successive separations" (75). Thus in the uranium series uranium 1 breaks down to form uranium Xj, and this in turn disintegrates to form the successive products uranium X2, uranium Z, uranium 2, and uranium Y. 

Radioactive decay usually does not immediately lead to a stable end product, but to other unstable nuclei that form a decay series (Kiefer 1990). The most important examples of unstable nuclei are started by very heavy, naturally occurring nuclei. Because the mass number changes only with a decay, all members of a series can be classified according to their mass numbers (see the uranium-238 decay series in Figure 32.2). A total of three natural decay series — formed at the birth of our planet — are named after their parent isotope Th, and (Figure 32.3). Several shorter decay series also exist. For example, Sr decays with a Tb 1/2 of 28 years by [3 emission to °Y, which in turn disintegrates (P emission) with a Tb 1/2 of 64 h to the stable °Zr (Kiefer 1990). Other examples of known radionuclides since the Earth s origin include " °K and Rb. In hazard assessments, all members of a decay series must be considered. 

The radium isotope of mass number 226 occurs in the uranium (2n + 2) alpha-decay series. Its half-life is 1.620 years, and it yields radon-222 by o-disintegration. Other naturally occurring isotopes of radium are "v Ra in... 

The fake Vermeers were eventually dated to the 1930s and 40s by Bernard Keisch at the Brookhaven National Laboratories in 1968. He analysed the radioactivity in the paintings and showed that the lead white that van Meegeren had used was relatively new. Lead contains a little radioactive uranium-238 which disintegrates through a series of... 

The radioactive decay of uranium and thorium results in the formation of a series of isotopes that are radiogenic by themselves and keep disintegrating into stable lead isotopes. These radioactive disintegrations are accompanied by the emissions of 4He atoms. Three such radioactive series exist ... 

Radium was discovered by Marie Curie (1867-1934) in pitchblende, a uranium ore. Radium is produced from a series of disintegrations, starting with and each producing an alpha particle or a beta particle (and possibly a gamma particle). Without looking at any figure or table, but using the mass number of l Ra, deduce how many alpha particles have been emitted from to produce this isotope of radium. 

The Uranium Series o Radioactive Disintegrations. When an alpha particle (He++) is emitted by an atomic nucleus the nuclear charge decreases by two units the element hence is transmuted into the element two columns to the left in the periodic table. Its mass number (atomic weight) decreases by 4, the mass of the alpha particle. 

The Uranium Series.—Ordinary uranium preparations emit a-, j8-, and y-rays. The a-rays alone come from the element uranium, the j8- and y-rays coming from products of its disintegration. By expulsion of one a-particle, the atom of uranium, of atomic -weight 238, produces an atom of a new element, kno vn as uranium X, of atomic w eight 234. This new atom is more unstable than the original uranium atom and emits a jS-partide, producing an atom of another new element, knowm as uranium Xg, of the same atomic weight as uranium X. ... 

Discovery and Nature of Radioactivity—Radioactive Constants—The Uranium Series—The Disintegration Products of Uranium and their Separation— Uranium I—Uranium Xj—Uranium Xj—Uranium Z—Uranium II— Ionium—Uranium Y—Protoaetinium. 

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