Nuclear chemistry elements

Another area where controlled-potential coulometry has found application is in nuclear chemistry, in which elements such as uranium and polonium can be determined at trace levels. Eor example, microgram quantities of uranium in a medium of H2SO4 can be determined by reducing U(VI) to U(IV) at a mercury working electrode. 

Elemental boron is used in very diverse industries from metallurgy (qv) to electronics. Other areas of appHcation include ceramics (qv), propulsion, pyrotechnics, and nuclear chemistry. Boron is nontoxic. Workplace hygienic practices, however, include a voiding the breathing of boron dust or fine powder. 

Nuclear reactions involving technetium have been actively studied until today. Our interest in the nuclear chemistry of technetium is based on various reasons. Technetium was the first artificially produced element in the periodic table, a weighable amount of technetium ("Tc) is now available, and 99mTc is one of the most important radionuclides in nuclear medicine. In addition, technetium is an element of importance from a nuclear safety point of view. 

Bigazzi, G., Meloni, S., Oddone, M. and Radi, G. (1986). Provenance studies of obsidian artefacts trace elements and data reduction. Journal of Radio-analytical and Nuclear Chemistry Articles 98 353-363. 

Farnum, J. F., Glascock, M. D., Sandford, M.K., and Gerritsen, S. (1995). Trace-elements in ancient human bone and associated soil using NAA. Journal of Radioanalytical and Nuclear Chemistry 196 267-274. 

Zheng, J., Goessler, W., Geiszinger, A., et al. (1997). Multi-element determination in earthworms with instrumental neutron activation analysis and inductively coupled plasma mass spectrometry a comparison. Journal of Radioanalytical and Nuclear Chemistry 223 149-155. 

This useful technique has made many contributions to radio- and nuclear chemistry, although primarily for investigational purposes rather than those of separation for its own ends. Thode and his co-workers have made many investigations into the inert gases produced in fission and it was by these means that the fine structure of fission was first discovered (79), (121). Since then several other elements, the rare-earths, strontium, caesium, zirconium, and molybdenum (35), (50), (132) have been investigated, and the isotopic ratios obtained provide relative values of fission-yields which are more accurate than can be obtained by standard radiochemical means. The latter technique, however, requires rather less heavily irradiated material than the former. 

Iskander, F. Y. (1994). Measurements of 27 elements in garden and lawn fertilizers using instrumental neutron-activation. Journal of Radioanalytical and Nuclear Chemistry-Articles 180(1) 25-28. 

Up to this point, we have been describing single atoms and their electrons. Chemical reactions occur when electrons from the outer shells of atoms of two or more different elements interact. Nuclear reactions involve interactions of particles in the nucleus (mainly protons and neutrons) of atoms, not the atoms electrons. This distinction is fundamental. The former is atomic chemistry (or electron chemistry), and the latter is nuclear chemistry (or nuclear physics). 

Gladney ES, Perrin DR, Robinson RD, et al. 1984. Multitechnique determination of elemental concentrations in NBS urban air particulate SRM 1648 and evaluation of its use for quality assurance. Journal of Radioanalytical and Nuclear Chemistry 83 379-386. 

Polasek, M. Jervis, R. E. 1994. Elements in car and truck tires and their volatilization upon incineration. Journal of Radioanalytical and Nuclear Chemistry, Articles, 179, 205-209. 

Chemists and physicists have collaborated since the middle of the twentieth century to make new elements substances never before seen on Earth. They are expanding the Periodic Table, step by painful step, into uncharted realms where it becomes increasingly hard to predict which elements might form and how they might behave. This is the field of nuclear chemistry. Instead of shuffling elements into new combinations - molecules and compounds - as most chemists do, nuclear chemists are coercing subatomic particles (protons and neutrons) to combine in new liaisons within atomic nuclei. 

How would you know if you have made a new element Neutron irradiation of a small sample of uranium could be expected to produce only an extremely tiny amount of element 93, perhaps a thousand atoms or so. Because they are radioactive, such atoms should be easy to spot with a Geiger counter. But first you need to separate them from the uranium, which is radioactive too. This is why the nuclear physicists needed the help of chemists. From its beginning with the work of the Curies, nuclear chemistry or radiochemistry has had to work with incredibly tiny samples of rare elements, and has required a skill at analysis - separating substances into their elemental components - that Antoine Lavoisier could never have dreamed of. 

J Ju elements in the periodic table exist in unstable versions called radioisotopes (see Chapter 3 for details). These radioisotopes decay into other (usually more stable) elements in a process called radioactive decay. Because the stability of these radioisotopes depends on the composition of their nuclei, radioactivity is considered a form of nuclear chemistry. Unsurprisingly, nuclear chemistry deals with nuclei and nuclear processes. Nuclear fusion, which fuels the sun, and nuclear fission, which fuels a nuclear bomb, are examples of nuclear chemistry because they deal with the joining or splitting of atomic nuclei. In this chapter, you find out about nuclear decay, rates of decay called half-lives, and the processes of fusion and fission. 

All the chemical changes and many of the physical changes that we have studied so far involve alterations in the electronic structures of atoms. Electron-transfer reactions, emission and absorption spectra, and X rays result from the movement of electrons from one energy level to another. In all of these, the nuclei of the atoms remain unchanged, and different isotopes of the same element have the same chemical activity. Nuclear chemistry, or radioactivity, differs from other branches of chemistry in that the important changes occur in the nucleus. These nuclear changes also are represented by chemical equations. However, because the isotopes of the same element may, from a nuclear standpoint, be very different in reactivity, it is necessary that the equations show which isotopes are involved. 

Element 106 has been named Seaborgiutn (Sb) in honor of the Glenn T. Scaborg. the father ot nuclear chemistry and discoverer of plutonium. 

In nuclear chemistry, the term mole fraction may be used to indicate the number of atoms of a given isotope in an isotopic mixlure. as a fraction of the total number of atoms of that element in the mixture. 

Nuclear chemistry consists of a four-pronged endeavor made up of (a) studies of the chemical and physical properties of the heaviest elements where detection of radioactive decay is an essential part of the work, (b) studies of nuclear properties such as structure, reactions, and radioactive decay by people trained as chemists, (c) studies of macroscopic phenomena (such as geochronology or astrophysics) where nuclear processes are intimately involved, and (d) the application of measurement techniques based upon nuclear phenomena (such as nuclear medicine, activation analysis or radiotracers) to study scientific problems in a variety of fields. The principal activity or mainstream of nuclear chemistry involves those activities listed under part (b). 

As a branch of chemistry, the activities of nuclear chemists frequentiy span several traditional areas of chemistry such as organic, analytical, inorganic, and physical chemistry. Nuclear chemistry has ties to all branches of chemistry. For example, nuclear chemists are frequently involved with the synthesis and preparation of radiolabeled molecules for use in research or medicine. Nuclear analytical techniques are an important part of the arsenal of the modem analytical chemist. The study of the actinide and transactinide elements has involved the joint efforts of nuclear and inorganic chemists in extending knowledge of the periodic table. Certainly, the physical concepts and reasoning at the heart of modem nuclear chemistry are familiar to physical chemists. In this book we will touch on many of these interdisciplinary topics and attempt to bring in familiar chemical concepts. 

The chemical elements are the building blocks of nature. All substances are combinations of these elements. There are (as of 2005) 113 known chemical elements with the heaviest naturally occurring element being uranium (Z = 92). The 22 heaviest chemical elements, the transuranium elements, are manmade. The story of their synthesis, their properties, their impact on chemistry and physics, and their importance to society is fascinating. This story is of particular importance to nuclear chemistry because most of our knowledge of these elements and their properties comes from the work of nuclear chemists, and such work continues to be a major area of nuclear chemical research. One of us (GTS) has been intimately involved in the discovery and characterization of these transuranium elements. 

Freitas, M.C. and Pacheco, A.M.G. (2007) Elemental concentrations of aerosols near Portuguese power plants by INAA and PIXE. Journal of Radioanalytical and Nuclear Chemistry, 271(1), 185-89. 

Kutle, A., OreSCanin, V., ObhodaS, J. and Valkovid, V. (2004) Trace element distribution in geochemical environment of the island Krk and its influence on the local population. Journal of Radioanalytical and Nuclear Chemistry, 259(2), 271-76. 

Lin, X. and Henkelmann, R. (2003) Contents of arsenic, mercury and other trace elements in Napoleon s hair determined by INAA using the ko-method. The Journal of Radioanalytical and Nuclear Chemistry, 257(3), 615-20. 

Olmez, E.I., Kut, D., Bilge, A.N. and Olmez, I. (2004) Regional elemental signatures related to combustion of lignites. The Journal of Radioanalytical and Nuclear Chemistry, 259(2), 227-31. 

If we understand nuclear chemistry to mean the study of the effects of nuclear transformations, especially of proton number (i.e., transformation of one element to another), then from the physicist s or chemist s viewpoint the nuclear chemistry of noble gases is neither more nor less interesting than any other group of elements, and there is no reason to distinguish noble gases from any other elements. From the geochemist s viewpoint, which defines the scope of this book, particular interest is attached to natural nuclear chemistry effects, which involve enough nuclear transformations to produce observable variations in elemental or, more commonly,... 

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