Transmutation reactions

To transmute a substance is to change it into a different substance. Early alchemists attempted unsuccessfully to transmute lead into gold. The reason that they failed is because lead and gold are both elements. An element is identified by the number of protons found in its nucleus. The methods the alchemists used were ordinary chemical reactions that only involved interactions among the electrons in atoms, not changes to the nuclei of the atoms. To change one element into another element requires that the number of protons 

Transmutation means change or transformation. The term is used to describe what happens when one element is changed into another element. 

Today s chemists have succeeded in changing lead into gold. They have even changed platinum into gold. The costs are prohibitive, however, so there is no practical reason for doing either one. 

Ernest Rutherford (1871-1937) was the British physicist who performed the first nuclear transmutation. In 1911, Rutherford bombarded nitrogen nuclei with alpha particles and succeeded in converting nitrogen into oxygen, as shown in the following equation  

Since that time nuclear reactors around the world have produced hundreds of isotopes of most of the elements in the periodic table. As discussed in Chapter 13, some of these isotopes are used daily in nuclear medicine. Technetium-99m is a gamma ray emitter used daily in hospitals. Tc-99m is produced from the beta decay of molybdenum-99 as shown in the following reaction  

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In a transmutation reaction, the incident neutron is absorbed, forming a compound nucleus that decays so that the residual nucleus is different from the target nucleus and the outgoing channel typically includes two particles. A transmutation reaction can be written as... 

Complete the following nuclear equations for transmutation reactions ... 

V I those with atomic numbers higher than uranium, do not occur naturally but are produced by nuclear transmutation reactions, discussed in Section 22.7. 

The fast neutrons will cause atomic displacement and transmutation reactions in the wall material. For example after 20 years of operation, a niobium wall would contain 10 at % Zr, 0.06 at % Y, 0.28 at % He, and 0.5 at %H53h The impact on the mechanical properties of construction materials due to displacement damage and radioactive transformation is under intensive study but does not properly fall under the subject matter of this chapter. 

In almost all of the previous examples, we have looked at nuclear reactions that occur by spontaneous decay. There are other types of nuclear reactions that can occur, known as transmutation reactions. These reactions can be induced by forcing a reaction between the nucleus of an element and nuclear particles (such as neutrons), or nuclei. Ernest Rutherford carried out the first transmutation by bombarding nitrogen-14 nuclei with alpha particles. This resulted in the production of oxygen-17 and a proton, as shown below ... 

Boyle made it clear that chemists principles were not permanent, but transmutable. As Kuhn has pointed out, Boyle s dynamic atomism entailed transmutation reactions of not simply gold from lead, but anything from almost anything. Boyle exploited the polemical utility of... 

The discovery that a transmutation had happened started a flood of research. Soon after Harkins and Blackett had observed a nitrogen atom forming oxygen, other transmutation reactions were discovered by bombarding various elements with alpha particles. As a result, chemists have synthesized, or created, more elements than the 93 that occur naturally. These are synthetic elements. All of the transuranium elements, or those with more than 92 protons in their nuclei, are synthetic elements. To make them, one must use special equipment, called particle accelerators, described below. 

All the nuclear reactions that have been described thus far are examples of radioactive decay, where one element is converted into another element by the spontaneous emission of radiation. This conversion of an atom of one element to an atom of another element is called transmutation. Except for gamma emission, which does not alter an atom s atomic number, all nuclear reactions are transmutation reactions. Some unstable nuclei, such as the uranium salts used by Henri Becquerel, undergo transmutation naturally. However, transmutation may also be forced, or induced, by bombarding a stable nucleus with high-energy alpha, beta, or gamma radiation. 

In 1919, Ernest Rutherford performed the first laboratory conversion of one element into another element. By bombarding nitrogen-14 with high-speed alpha particles, an unstable fluorine-18 occurred, and then oxygen-17 was formed. This transmutation reaction is illustrated below. 

You are given all of the particles involved in an induced transmutation reaction, from which you must write the balanced nuclear equation. Because the alpha particle bombards the aluminum atom, they are reactants and must appear on the reactant side of the reaction arrow. Obtain the atomic number of aluminum and phosphorus from the periodic table. Write out the nuclear reaction, being sure to include the alpha particle (reactant) and the neutron (product). 

For more practice with transmutation reactions, go to Supplemental Practice Problems in Appendix A. 

Describe the process of induced transmutation. Give two examples of induced transmutation reactions that produce transuranium elements. 

Define transmntation. Are all nnclear reactions also transmutation reactions Explain. (25.3)... 

Rutherford, Sir Ernest (1871-1937). First to prove radioactive decay of heavy elements and to carry out a transmutation reaction (1919). Discovered half-life of radioactive elements. Nobel Prize 1908. 

In fission reactors the transmutation reactions of principal importance involving neutrons are capture and fission. All nuclides (except He) take part in the radiative capture reaction ( , y), an example of which is... 

Lord Rutherford and his group of scientists were the first persons to produce and detect artificial nuclear transmutations in 1919. He bombarded nitrogen in the air with the a-particles emitted in the decay of Po. The transmutation reaction involved the absorption of an a-particle by the nuclei to produce and a proton (a hydrogen nucleus). This reaction can be written as... 

With the development of nuclear reactors and charged particle accelerators (commonly referred to as atom smashers ) over the second half of the twentieth century, the transmutation of one element into another has become commonplace. In fact some two dozen synthetic elements with atomic numbers higher than naturally occurring uranium have been produced by nuclear transmutation reactions. Thus, in principle, it is possible to achieve the alchemist s dream of transmuting lead into gold, but the cost of production via nuclear transmutation reactions would far exceed the value of the gold. SEE ALSO Alchemy Nuclear Chemistry Nuclear Fission Radioactivity Transactinides. 

As an example of a nuclear transmutation reaction, let us consider the following ... 

Induced Transmutation Reaction Equations Write a balanced nuclear equation for the induced transmutation of oxygen-16 into nitrogen-13 by proton bombardment. An alpha particle is emitted from the nitrogen atom in the reaction. 

You are given all of the particles involved in an induced transmutation reaction. Because the proton bombards the oxygen atom, they are reactants and must appear on the reactant side of the reaction arrow. 

In an FRP, all these reactions are susceptible to occur, but in a concentrated monomer environment, the dominating reactions are the addition (propagation) and termination by disproportionation or coupling. The fragmentation, abstraction, and transmutation reactions are detrimental for the chain formation however, sometimes they can be induced to regulate the degree of polymerization. 

For the minor actinides, the transmutation process consists of the capture of one or more neutrons until a more fissionable isotope is formed. For the actinides, the most important transmutation reaction is fission because it results in the removal of the isotope from the minor actinide inventory and replaces it with two typically shorter-lived, less toxic fission fragments. With more energetic neutrons, the (n,2n) reaction is also useful because this reaction transforms fertile actinides with low fission probabilities to more fissile actinides with higher fission probabilities. Neutron capture reactions that produce less fissionable isotopes merely add to the inventory of minor actinides. 

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