Chemistry
Transmutation
Transmutation is the process of changing one element into another by altering the number of protons in the nucleus. This can be achieved through nuclear reactions such as radioactive decay, fusion, and fission. Transmutation has important applications in nuclear energy and medicine.
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8 Key excerpts on "Transmutation"
eBook - PDF- James E. Martin(Author)
- 2013(Publication Date)
- Wiley-VCH(Publisher)
21 3 Radioactive Transformation "Don¢t call it Transmutation...they¢ll have our heads off as alchemists." Ernest Rutherford (1902) Much of what has been learned about atomic and nuclear physics is based on this remarkable property by which certain nuclei transform themselves spontaneously from one value of Z and N to another. Discovery of the emissions of alpha and beta particles established that atoms are not indivisible, but are made up of more fundamental particles. Use of the emitted particles as projectiles to transform nuclei led eventually to some of the greatest discoveries in physics. The process of radioactive transformation was recognized by Rutherford as Transmutation of one element to another. It is also quite common to use the term radioactive decay, but transformation is a more accurate description of what actu- ally happens; decay suggests a process of disappearance when what actually hap- pens is an atom with excess energy transforms itself to another atom that is either stable or one with more favorable conditions to proceed on to stability. 3.1 Processes of Radioactive Transformation Atoms undergo radioactive transformation because constituents in the nucleus are not arrayed in the lowest potential energy states possible; therefore, a rear- rangement of the nucleus occurs in such a way that this excess energy is emitted and the nucleus is transformed to an atom of a new element. The transformation of a nucleus may involve the emission of alpha particles, negatrons, positrons, electromagnetic radiation in the form of x-rays or gamma rays, and, to a lesser extent, neutrons, protons, and fission fragments. Such transformations are spon- taneous, and the Q-values are positive; if the array of nuclear constituents is in the lowest potential energy states possible, the transformation yields a stable atom; if not, another transformation must occur.
eBook - ePub- James E. Martin(Author)
- 2013(Publication Date)
- Wiley-VCH(Publisher)
3Radioactive Transformation
“Don’t call it Transmutation…they’ll have our heads off as alchemists.” Ernest Rutherford (1902)Much of what has been learned about atomic and nuclear physics is based on this remarkable property by which certain nuclei transform themselves spontaneously from one value of Z and N to another. Discovery of the emissions of alpha and beta particles established that atoms are not indivisible, but are made up of more fundamental particles. Use of the emitted particles as projectiles to transform nuclei led eventually to some of the greatest discoveries in physics.The process of radioactive transformation was recognized by Rutherford as Transmutation of one element to another. It is also quite common to use the term radioactive decay, but transformation is a more accurate description of what actually happens; decay suggests a process of disappearance when what actually happens is an atom with excess energy transforms itself to another atom that is either stable or one with more favorable conditions to proceed on to stability.3.1Processes of Radioactive Transformation
Atoms undergo radioactive transformation because constituents in the nucleus are not arrayed in the lowest potential energy states possible; therefore, a rearrangement of the nucleus occurs in such a way that this excess energy is emitted and the nucleus is transformed to an atom of a new element. The transformation of a nucleus may involve the emission of alpha particles, negatrons, positrons, electromagnetic radiation in the form of x-rays or gamma rays, and, to a lesser extent, neutrons, protons, and fission fragments. Such transformations are spontaneous, and the Q-values are positive; if the array of nuclear constituents is in the lowest potential energy states possible, the transformation yields a stable atom; if not, another transformation must occur.
eBook - ePubNuclear and Radiochemistry
Fundamentals and Applications
- Jens-Volker Kratz(Author)
- 2021(Publication Date)
- Wiley-VCH(Publisher)
13 Chemical Effects of Nuclear Transmutations13.1 General Aspects
The chemical binding energies between atoms vary between about 40 and 400 kJ mol−1 , corresponding to about 0.4–4 eV (1 eV ≈ 96.5 kJ mol−1 ). The energies involved in nuclear reactions are on the order of several megaelectronvolts, and parts of these energies are transmitted to the atoms in the form of recoil and excitation energy. Therefore, chemical bonds are strongly affected by nuclear Transmutations. High kinetic energy of single atoms does not mean high temperature, because the temperature of a system is given by the mean kinetic energy of all the atoms or molecules, (for three degrees of freedom). However, deviating from the usual concept of temperature, the temperature equivalent of a single particle may be related to its kinetic energy by the equation(13.1)Because energies on the order of 1 eV−1 MeV are transmitted to the atoms by nuclear Transmutations, corresponding to temperature equivalents on the order of 104 –1010 K, these atoms are called “hot atoms” and their chemistry is called “hot‐atom chemistry,” or “recoil chemistry” if the recoil effects are considered.Chemical effects of nuclear Transmutations were first observed by L. Szilard and T.A. Chalmers in 1934 (Szilard and Chalmers 1934 ) when irradiating ethyl iodide with neutrons. They found several chemical species containing 128 I that are produced by the chemical effects of the nuclear reaction 127 I(n, γ)128 I. In the following years, the chemical effects of radioactive decay were observed in gaseous compounds, liquids, and solids. The chemical effects of nuclear reactions can be divided into primary effects taking place in the atom involved in the nuclear reaction, secondary effects in the molecules or other associations of atoms, and subsequent reactions. Primary and secondary effects are observed within about 10−11
eBook - ePubNuclear and Radiochemistry
Fundamentals and Applications
- Jens-Volker Kratz, Karl Heinrich Lieser(Authors)
- 2013(Publication Date)
- Wiley-VCH(Publisher)
13 Chemical Effects of Nuclear Transmutations13.1 General Aspects
The chemical binding energies between atoms vary between about 40 and 400 kJ mol−1 , corresponding to about 0.4–4 eV (1 eV ≈ 96.5 kJ mol−1 ). The energies involved in nuclear reactions are on the order of several megaelectronvolts, and parts of these energies are transmitted to the atoms in the form of recoil and of excitation energy. Therefore, chemical bonds are strongly affected by nuclear Transmutations. High kinetic energy of single atoms does not mean high temperature, because the temperature of a system is given by the mean kinetic energy of all the atoms or molecules, (for three degrees of freedom). However, deviating from the usual concept of temperature, the temperature equivalent of a single particle may be related to its kinetic energy by the equation(13.1)Because energies on the order of 1 eV to 1 MeV are transmitted to the atoms by nuclear Transmutations, corresponding to temperature equivalents on the order of 104 to 1010 K, these atoms are called “hot atoms ” and their chemistry is called “hot-atom chemistry ,” or “recoil chemistry” if the recoil effects are considered.Chemical effects of nuclear Transmutations were first observed by L. Szilard and T.A. Chalmers in 1934 [1] when irradiating ethyl iodide with neutrons. They found several chemical species containing 128 I that are produced by the chemical effects of the nuclear reaction 127 I(n, γ)128 I. In following years, the chemical effects of radioactive decay were observed in gaseous compounds, liquids, and solids. The chemical effects of nuclear reactions can be divided into primary effects taking place in the atom involved in the nuclear reaction, secondary effects in the molecules or other associations of atoms, and subsequent reactions. Primary and secondary effects are observed within about 10−11 s after the nuclear reaction.Primary effects comprise recoil of the nucleus and excitation of the electron shell of the atom. The excitation may be due to recoil of the nucleus, change of atomic number Ζ
eBook - PDF- Paul Flowers, Klaus Theopold, Richard Langley, William R. Robinson(Authors)
- 2019(Publication Date)
- Openstax(Publisher)
When a nuclear reaction occurs, the total mass (number) and the total charge remain unchanged. 21.3 Radioactive Decay Nuclei that have unstable n:p ratios undergo spontaneous radioactive decay. The most common types of radioactivity are α decay, β decay, γ emission, positron emission, and electron capture. Nuclear reactions also often involve γ rays, and some nuclei decay by electron capture. Each of these modes of decay leads to the formation of a new nucleus with a more stable n:p ratio. Some substances undergo radioactive decay series, proceeding through multiple decays before ending in a stable isotope. All nuclear decay processes follow first-order kinetics, and each radioisotope has its own characteristic half-life, the time that is required for half of its atoms to decay. Because of the large differences in stability among nuclides, there is a very wide range of half-lives of radioactive substances. Many of these substances have found useful applications in medical diagnosis and treatment, determining the age of archaeological and geological objects, and more. 21.4 Transmutation and Nuclear Energy It is possible to produce new atoms by bombarding other atoms with nuclei or high-speed particles. The products of these Transmutation reactions can be stable or radioactive. A number of artificial elements, including technetium, astatine, and the transuranium elements, have been produced in this way. Nuclear power as well as nuclear weapon detonations can be generated through fission (reactions in which a heavy nucleus is split into two or more lighter nuclei and several neutrons). Because the neutrons may induce additional fission reactions when they combine with other heavy nuclei, a chain reaction can result. Useful power is obtained if the fission process is carried out in a nuclear reactor. The conversion of light nuclei into heavier nuclei (fusion) also produces energy.
eBook - PDF- Edward J. Neth, Paul Flowers, Klaus Theopold, Richard Langley, William R. Robinson(Authors)
- 2019(Publication Date)
- Openstax(Publisher)
When a nuclear reaction occurs, the total mass (number) and the total charge remain unchanged. 20.3 Radioactive Decay Nuclei that have unstable n:p ratios undergo spontaneous radioactive decay. The most common types of radioactivity are α decay, β decay, γ emission, positron emission, and electron capture. Nuclear reactions also often involve γ rays, and some nuclei decay by electron capture. Each of these modes of decay leads to the formation of a new nucleus with a more stable n:p ratio. Some substances undergo radioactive decay series, proceeding through multiple decays before ending in a stable isotope. All nuclear decay processes follow first-order kinetics, and each radioisotope has its own characteristic half-life, the time that is required for half of its atoms to decay. Because of the large differences in stability among nuclides, there is a very wide range of half-lives of radioactive substances. Many of these substances have found useful applications in medical diagnosis and treatment, determining the age of archaeological and geological objects, and more. 20.4 Transmutation and Nuclear Energy It is possible to produce new atoms by bombarding other atoms with nuclei or high-speed particles. The products of these Transmutation reactions can be stable or radioactive. A number of artificial elements, including technetium, astatine, and the transuranium elements, have been produced in this way. Nuclear power as well as nuclear weapon detonations can be generated through fission (reactions in which a heavy nucleus is split into two or more lighter nuclei and several neutrons). Because the neutrons may induce additional fission reactions when they combine with other heavy nuclei, a chain reaction can result. Useful power is obtained if the fission process is carried out in a nuclear reactor. The conversion of light nuclei into heavier nuclei (fusion) also produces energy.
- Martha Mackin(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
SEVENTEEN Nuclear chemistry OVERVIEW In previous chapters we studied chemical changes that occur as the result of changes in electron arrangements of atoms. In Chapter 17 we will study changes that occur in the nucleus of the atom. When the nuclei of unstable atoms disintegrate and give off radiation, the process is called radioactivity. These unstable atoms may occur in nature or may be produced artifically. This chapter defines the particles that are given off during the decay and explains how to write nuclear equations to represent the nuclear reactions that occur. Equations can be used to show the radioactive disintegration of both naturally occurring and artificial radioactive elements. They can also show the method by which artificial radioactive isotopes may be prepared. Half-life for radioisotopes is explained. Fission and fusion are nuclear changes in which mass is converted into large amounts of energy. Nuclear reactors utilizing fission produce heat energy, which is converted into electricity; fusion reactors are being developed as a commercial source of energy. Methods for and the units used in measuring radiation are included in the chapter. Various uses for radioisotopes, and the effects upon health of the radiation produced are also explained. **Specifics** 1. Definitions for the following terms should be learned: nuclear radiation accelerators radioactivity transuranium elements alpha radiation half-life beta radiation radiocarbon dating gamma radiation binding energy natural radioactivity fission radioactive disintegration series chain reaction artificial radioactivity critical mass radioisotopes breeder reactor neutron capture or fusion neutron activation radioactive tracer Transmutation 470 Chapter 17 Topical Outline 471 2. General concepts that should be learned: CHAPTER 17 TOPICAL OUTLINE I. Description and interpretation of nuclear reactions 17.1 Radioactivity A.
eBook - ePubChemistry
The Molecular Nature of Matter
- Neil D. Jespersen, Alison Hyslop(Authors)
- 2018(Publication Date)
- Wiley(Publisher)
compound nucleus , has excess energy that quickly becomes distributed among all of the nucleons, but the nucleus is nevertheless rendered somewhat unstable. To get rid of the excess energy, a compound nucleus generally ejects something (e.g., a neutron, proton, or electron) and often emits gamma radiation as well. This leaves a new nucleus of an isotope different from the original target, so a Transmutation has occurred overall.- Compound here refers only to the idea of combination, not to a chemical.
Ernest Rutherford observed the first example of artificial Transmutation. When he let alpha particles pass through a chamber containing nitrogen atoms, an entirely new radiation was generated, one much more penetrating than alpha radiation. It proved to be a stream of protons (Figure 20.11 ). Rutherford was able to show that the protons came from the decay of the compound nuclei of fluorine-18, produced when nitrogen-14 nuclei captured bombarding alpha particles:- The asterisk, *, symbolizes a high-energy nucleus—a compound nucleus.
Another example is the synthesis of alpha particles from lithium-7, in which protons are used as bombarding particles. The resulting compound nucleus, beryllium-8, splits into two alpha particles.+He 2 4alpha particle→N714nitrogen nucleus→F *918flourine( compound nucleus )+O817oxygen( a rare but stable isotope )p 1 1proton( high energy )+p 1 1proton→Li 3 7lithium→Be * 4 8beryllium2alpha particlesHe 2 4Figure 20.11 Transmutation of nitrogen into oxygen. When the nucleus of nitrogen-14 captures an alpha particle, it becomes a compound nucleus of fluorine-18. This then expels a proton and becomes the nucleus of oxygen-17.Modes of Decay
A given compound nucleus can be made in a variety of ways. Aluminum-27, for example, forms by any of the following routes:→He 2 4+Na 11 23Al * 13 27→p 1 1+Mg 12 26Al * 13 27→H 1 2+Mg 12 25Al * 13 27- H 1 2
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