Alpha decay processes

Write balanced nuclear equations for beta decay, positron emission, electron capture, and alpha decay processes and calculate the maximum kinetic energies of particles emitted (Section 19.2, Problems 7-18). 

The study of the chemical behavior of concentrated preparations of short-Hved isotopes is compHcated by the rapid production of hydrogen peroxide ia aqueous solutions and the destmction of crystal lattices ia soHd compounds. These effects are brought about by heavy recoils of high energy alpha particles released ia the decay process. 

Such alpha-recoil plays a fundamental role in fractionating the nuclides from one another in the low-temperature environment. During igneous processes, on the other hand, alpha recoil is probably not important in the generation of disequilibria ( °Th, Ra, and Pa). Beattie (1993) pointed out that the time scale of annealing of alpha decay damage at high temperatures was much shorter than the time scale of decay of these nuclides. 

The alpha particles could be obtained from a natural decay process. At present, a variety of particles can be used to bombard nuclei (Table 22-3), some of which are raised to high energies in atom smashing machines. Again, nuclear equations can be written, in which the net charge and the total of the mass numbers on one side must be the same as their counterparts on the other side. 

He is found in natural gas deposits principally because alpha particles are produced during natural radioactive decay processes. These alpha particles are 4 He nuclei they obtain two electrons from the surrounding material to become helium atoms. This gaseous helium then accumulates with the natural gas trapped beneath the earth. Although other noble gases are produced by radioactive decay—notably 40 Ar—they are not produced in the large quantities that helium is. 

In the meantime, E. Rutherford (NLC 1908 ) studied the radioactivity discovered by Becquerel and the Curies. He determined that the emanations of radioactive materials include alpha particles (or rays) which are positively charged helium atoms, beta particles (or rays) which are negatively charged electrons, and gamma rays which are similar to x-rays. He also studied the radioactive decay process and deduced the first order rate law for the disappearance of a radioactive atom, characterized by the half-life, the time in which 50% of a given radioactive species disappears, and which is independent of the concentration of that species. 

Radium is extremely radioactive. It glows in the dark with a faint bluish light. Radiums radioisotopes undergo a series of four decay processes each decay process ends with a stable isotope of lead. Radium-223 decays to Pb-207 radium-224 and radium-228decay to Pb-208 radium-226 decays to Pb-206 and radium-225 decays to Pb-209. During the decay processes three types of radiation—alpha (a), beta ((5), and gamma (y)—are emitted. 

Uranium is the fourth metal in the actinide series. It looks much like other actinide metallic elements with a silvery luster. It is comparatively heavy, yet malleable and ductile. It reacts with air to form an oxide of uranium. It is one of the few naturally radioactive elements that is fissionable, meaning that as it absorbs more neutrons, it splits into a series of other lighter elements (lower atomic weights) through a process of alpha decay and beta emission that is known as the uranium decay series, as follows U-238—> Th-234—>Pa-234—>U-234—> Th-230 Ra-226 Rn-222 Po-218 Pb-2l4 At-218 Bi-2l4 Rn-218 Po-2l4 Ti-210—>Pb-210—>Bi-210 Ti-206—>Pb-206 (stable isotope of lead,... 

Dubnium s (Unp) most stable isotope, Db-268, is unstable with a half-life of 16 houts. It can change into lawtencium-254 by alpha decay ot into tuthetfotdium-268 by electton cap-tute. Both of these teactions occut thtough a series of decay processes and spontaneous fission (SF). Since so few atoms of unnilpentium (dubnium) are produced, and they have such a short half-life, its melting point, boiling point, and density cannot be determined. In addition, its valence and oxidation state are also unknown. 

Unnilseptium, or bohrium, is artificially produced one atom at a time in particle accelerators. In 1976 Russian scientists at the nuclear research laboratories at Dubna synthesized element 107, which was named unnilseptium by lUPAC. Only a few atoms of element 107 were produced by what is called the cold fusion process wherein atoms of one element are slammed into atoms of a different element and their masses combine to form atoms of a new heavier element. Researchers did this by bombarding bismuth-204 with heavy ions of chromium-54 in a cyclotron. The reaction follows Bi-209 + Cr-54 + neutrons = (fuse to form) Uns-262 + an alpha decay chain. 

Most of the chemical and physical properties of imniloctium (hassium) are unknown. What is known is that its most stable isotope (hassium-108) has the atomic weight (mass) of about 277. Hs-277 has a half-life of about 12 minutes, after which it decays into the isotope seaborgium-273 through either alpha decay or spontaneous fission. Hassium is the last element located at the bottom of group 8, and like element 107, it is produced by a cold fusion process that in hassium s case is accomplished by slamming iron (Fe-58) into particles of the isotope of lead (Pb-209), along with several neutrons, as follows ... 

Alpha particles are composed of two protons and two neutrons. Thus they have Z = 2, N = 2, and A = 4 and correspond to a helium nucleus He. The emission of a particles thus produces a decrease of 4 units in A. An unstable nuclide undergoing a decay may emit a particles of various energy and thus directly reach the ground level of the stable product. Alternatively, as in )3 emission, an intermediate excited state is reached, followed by y emission. Figure 11.7 shows, for example, the decay process of ioTh., which may directly attain the ground level of by emission of a particles of energy 5.421 MeV or intermediate excited states by emission of a particles of lower energy, followed by y emission. 

Allotrope different forms of an element characterized by different structures Alloy a mixture of two or more metals, for example, zinc + copper = brass Alpha Decay nuclear process in which an alpha particle is emitted by the nucleus... 

Many radioisotopes exist, but not all radioisotopes are created equal. Radioisotopes break down through three separate decay processes (or decay modes) alpha decay, beta decay, and gamma decay. The following sections show you equations detailing each type of decay. Note The symbols showing the isotope notation for each radioactive isotope cire as follows or 2 Y, where... 

The first type of decay process, called alpha decay, involves emission of an alpha pcirticle by the nucleus of an unstable atom. An alpha particle (a particle) is nothing more exotic than the nucleus of a helium atom, which is made of two protons and two neutrons. Emitting an alpha... 

ALPHA DECAY. The emission of alpha particles by radioactive nuclei. The name alpha particle was applied in the earlier years of radioactivity investigations, before it was fully understood what alpha particles are. It is known now that alpha particles are the same as helium nuclei. When a radioactive nucleus emits an alpha particle, its atomic number decreases by Z = 2 and its mass number by A = 4. The process is a spontaneous nuclear reaction, and the radionuclide that undergoes the emission is known as an alpha emitter. 

Alpha decay is characterized by the emission of an alpha particle from the parent nucleus. In this process, energy is released in the form of kinetic energy of the escaping alpha particle and the recoiling daughter nucleus. For example ... 

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