Transmutation

Transmutation is the process where one element is artificially changed into another element. Rutherford conducted the first transmutation experiment in 1919 when he bombarded nitrogen atoms with alpha particles. The nitrogen was transmuted into oxygen and hydrogen according to the reaction  

The process of transmutation produces most of the known isotopes. In fact, only about 10% of the approximately 3,000 known isotopes occur naturally. The rest are synthesized in large instruments called particle accelerators. 

Another design for particle accelerators is based on a circular arrangement. A cyclotron is similar to a linear accelerator wound into a spiral. A series of electromagnets causes the particles to move in a circle as they are accelerated by the electric field. According to Einstein s theory of relativity, an object s mass increases as it accelerates. In particle accelerators this is a problem because as the mass increases, the particle slows down and becomes out of sync with the changing electric field. A synchrotron is a cyclotron in which the electric field increases to compensate for the change in 

Particle accelerators are used to produce most isotopes by transmutation. All elements greater than uranium, known as the transuranium elements, have been produced in particle accelerators. For example. 

Pu-241 is produced when U-238 collides with an alpha particle  

Transmutation is the act of changing a substance, tangible or intangible, from one form or state into another. To the alchemists of old, this meant the conversion of one physical substance into another, particularly base metals such as lead into valuable silver and gold. To the modern scientists, this means the transformation of one element into another by one or a series of nuclear decays or reactions. 

Because each element has a different but fixed number of protons in the nucleus of the atom, which is the atomic number, the transmutation of one chemical element into another involves changing that number. Such a nuclear reaction requires millions of times more energy than was available through chemical reactions. Thus, the alchemist s dream of transmuting lead into gold was never chemically achievable. 

Although the alchemists failed to find a method for the transmntation of base metals into precious metals, a number of important chemical processes resulted from their efforts. For example, they extracted metals from ores produced a number of inorganic acids and bases that later became commercially important and developed the techniques of fusion, calcination, solution, filtration, crystallization, sublimation, and, most importantly, distillation. During the Middle Ages, they began to try to systematize the results of their primitive experiments and their fragments of information in order to explain or predict chemical reactions between substances. Thns the idea of chemical elements and the first primitive forms of the chemical Periodic Table appeared. 

Ironically, nuclear transmutations were taking place virtually under the noses of the alchemists (or nnder their feet), bnt they had neither the methods to detect nor the knowledge to use these happenings. The discovery of the nuclear transmutation process was closely linked to the discovery of radioactivity by Henri Becqnerel in 1896. Nnclear transmutations occnr dnring the spontaneous radioactive decay of naturally occurring thorium and uranium (atomic numbers 90 and 92, respectively) and the radioactive 

The idea of transmutation of elements in the natural decay chains did not accompany the discovery of radioactivity by Becquerel. However, Marie and Pierre Curie extended the investigations of Becquerel using a variety of 

The elements that come after uranium in the periodic table (atomic number 93) are called transuranium elements. These elements have all been produced in the laboratory using induced transmutation, and they all are radioactive. Scientists continue to work to produce new transuranium elements. 

Write a balanced nuclear equation for the induced transmutation of beryllium-9 into carbon-13 by alpha particle bombardment. 

Identify each participant in the reaction. Use the periodic table as needed and write the balanced equation. 

Complete the nuclear equation for each of the following induced transmutation reactions. 

Amount remaining = (Initial amount) y j where = the number of half-lives that has passed 

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. 

Transuranium elements The elements immediately following uranium in the periodic table—elements with atomic numbers 93 and greater—are known as the transuranium elements. All transuranium elements have been produced in the laboratory by induced transmutation and are radioactive. 

The main Tevatron ring has a diameter of more than 0.8 km and a circumference of about 6.4 km. The accelerator uses conventional and superconducting magnets to accelerate particles to high speeds and high energies. 

If you read through the names of the transuranium elements, you ll notice that many of them have been named in honor of their discoverers or the laboratories at which they were created. There are ongoing efforts throughout the world s major scientific research centers to synthesize new transuranium elements and study their properties. 

---

The new elements neptunium and plutonium have been produced in quantity by neutron bombardment of uranium. Subsequently many isotopes have been obtained by transmutation and synthetic isotopes of elements such as Ac and Pa are more easily obtained than the naturally occurring species. Synthetic species of lighter elements, e.g. Tc and Pm are also prepared. 

The transformations of the radioactive elements, whereby, e.g. uranium ultimately becomes lead, are not usually regarded as instances of transmutation because the processes are spontaneous, and cannot be controlled by the experimenter. 

Ernest O. Lawrence, inventor of the cyclotron) This member of the 5f transition elements (actinide series) was discovered in March 1961 by A. Ghiorso, T. Sikkeland, A.E. Larsh, and R.M. Latimer. A 3-Mg californium target, consisting of a mixture of isotopes of mass number 249, 250, 251, and 252, was bombarded with either lOB or IIB. The electrically charged transmutation nuclei recoiled with an atmosphere of helium and were collected on a thin copper conveyor tape which was then moved to place collected atoms in front of a series of solid-state detectors. The isotope of element 103 produced in this way decayed by emitting an 8.6 MeV alpha particle with a half-life of 8 s. 

Each of the elements has a number of isotopes (2,4), all radioactive and some of which can be obtained in isotopicaHy pure form. More than 200 in number and mosdy synthetic in origin, they are produced by neutron or charged-particle induced transmutations (2,4). The known radioactive isotopes are distributed among the 15 elements approximately as follows actinium and thorium, 25 each protactinium, 20 uranium, neptunium, plutonium, americium, curium, californium, einsteinium, and fermium, 15 each herkelium, mendelevium, nobehum, and lawrencium, 10 each. There is frequently a need for values to be assigned for the atomic weights of the actinide elements. Any precise experimental work would require a value for the isotope or isotopic mixture being used, but where there is a purely formal demand for atomic weights, mass numbers that are chosen on the basis of half-life and availabiUty have customarily been used. A Hst of these is provided in Table 1. 

Kilogram amounts of neptunium ( Np) have been isolated as a by-product of the large-scale synthesis of plutonium in nuclear reactors that utilise 235u and 238u as fuel. The following transmutations occur ... 

Potential fusion appHcations other than electricity production have received some study. For example, radiation and high temperature heat from a fusion reactor could be used to produce hydrogen by the electrolysis or radiolysis of water, which could be employed in the synthesis of portable chemical fuels for transportation or industrial use. The transmutation of radioactive actinide wastes from fission reactors may also be feasible. This idea would utilize the neutrons from a fusion reactor to convert hazardous isotopes into more benign and easier-to-handle species. The practicaUty of these concepts requires further analysis. 

Helium-3 [14762-55-1], He, has been known as a stable isotope since the middle 1930s and it was suspected that its properties were markedly different from the common isotope, helium-4. The development of nuclear fusion devices in the 1950s yielded workable quantities of pure helium-3 as a decay product from the large tritium inventory implicit in maintaining an arsenal of fusion weapons (see Deuterium AND TRITIUM) Helium-3 is one of the very few stable materials where the only practical source is nuclear transmutation. The chronology of the isolation of the other stable isotopes of the hehum-group gases has been summarized (4). 

Neptunium has been recovered during the reprocessing of defense-related fuels. The is recycled back to a reactor where it is transmuted to... 

The stmcture of the particles inside the nucleus was the next question to be addressed. One step in this direction was the discovery of the neutron in 1932 by Chadwick, and the deterrnination that the nucleus was made up of positively charged protons and uncharged neutrons. The number of protons in the nucleus is known as the atomic number, Z. The number of neutrons is denoted by A/, and the atomic mass is thus A = Z - - N. Another step toward describing the particles inside the nucleus was the introduction of two forces, namely the strong force that holds the protons and neutrons together in spite of the repulsion between the positive charges of the protons, and the weak force that produces the transmutation by P decay. 

Electron Capture and /5" "-Decay. These processes are essentially the inverse of the j3 -decay in that the parent atom of Z andM transmutes into one of Z — 1 andM. This mode of decay can occur by the capture of an atomic electron by the nucleus, thereby converting a proton into a neutron. The loss of one lepton (the electron) requires the creation of another lepton (a neutrino) that carries off the excess energy, namely Q — — Z(e ), where the last term is the energy by which the electron was bound to the atom before it was captured. So the process is equivalent to... 

This reaction is occasionally used for doping crystals uniformly after they have been grown. The process is called transmutation doping (37). 

J. Guldberg, ed., Neutron-Transmutation-Doped Silicon, Proceedings of the Third International Conference on Transmutation Doping of Silicon, Copenhagen, Denmark, Plenum Press, Inc., New York, 1981. 

Sir Isaac Newton spent much of his life pursuing an elusive dream, the transmutation of base materials into gold. Though he was not successful during his lifetime, he did manage to discover the equations of motion that, tliree centuries later, make alchemy possible on a computer. To perfonn this feat, Newton s equations need only be supplemented by the modem technology of free energy simulations. 

The emission of y rays follows, in the majority of cases, what is known as P decay. In the P-decay process, a radionuclide undergoes transmutation and ejects an electron from inside the nucleus (i.e., not an orbital electron). For the purpose of simplicity, positron and electron capture modes are neglected. The resulting transmutated nucleus ends up in an excited nuclear state, which prompdy relaxes by giving offy rays. This is illustrated in Figure 2. 

Nuclear power reactors cause the transmutation of chemicals (uranium and plutonium) to fission products using neutrons as the catalyst to produce heat. Fossil furnaces use the chemical reaction of carbon and oxygen to produce CO2 and other wastes to produce heat. There is only one reaction and one purpose for nuclear power reactors there is one reaction but many puiposes for fossil-burning furnaces there are myriad chemical processes and purposes. 

Fullwood, R. R. and R. R. Jackson, 1980, Partitioning-Transmutation Program Final Report VI Short Term Risk Analyis Reprocessing, Refabrication, and Transportation," ORNL/TM6986, and ORNL/Sub-80/31048/1. 

First artificial transmutation of an element Nfa.pl gO 192S-8 First abundance data on stars (spectroscopy)... 

J. D. Cockroft (Harwell) and E. T. S. Walton (Dublin) pioneer work on the transmutation of atomic nuclei by artificially accelerated atomic particles. 

Kem-umwandlung, /. nuclear transformation, transmutation, -verknlipfung,/. linkage to a nucleus, -verschmelzimg, /. nuclear fusion, -weehselwirkung, /. nuclear interaction, -werkstoff, m. core material. -woUe,/. prime wool, -zahl, /. number of nuclei, -zelle, /. nuclear cell, -zerfall, m. nuclear disintegration. -zerplatzen, n. nuclear explosion or disintegration. 

Umwandltmg, /. conversion, transformation, change transmutation metamorphosis (GrammaT) inflection. 

Unstable isotopes decompose (decay) by a process referred to as radioactivity. Ordinarily the result is the transmutation of elements the atomic number of the product nucleus differs from that of the reactant. For example, radioactive decay of produces a stable isotope of nitrogen, N. The radiation given off (Figure 2.6) may be in the form of—... 

---