EDUCATION
Freshman chemistry curriculum should include nuclear concepts • NUCLEAR - Should nuclear con cepts be included in the freshman chemistry curriculum? Yes, because they provide a unified approach to modern concepts of structure of all forms of matter—nuclei, atoms, and molecules—several scientists/educators told the Symposium on The Place of Nuclear Science Concepts in The Chemistry Curriculum. Moreover, they add, to develop a first (and many times last) course in chemistry at the university level, one should strive for an all-embracing view. This can be accomplished by looking for the common ingredient. The quantum nature of matter is be ing proposed as that ingredient. The incorporation of nuclear phenomena, whenever possible, makes the course relevant for the student. This relevancy results, Prof. A. A. Caretto of Carnegie-Mellon University says, because nuclear and quantum concepts are modern and, moreover, the majority of research chemists to day are involved in the elucidation of problems of molecular structure in one form or another. Aside from pedagogical reasons, there are practical advantages which show the relevancy of nuclear con cepts. These concepts: • Provide a better understanding of NMR spectroscopy as used to eluci date nuclear structure and Mossbauer spectroscopy for determining molecu lar structure. • Permit the presentation of the meaning of excited states in a simple way. • Enable the presentation of the periodicity of nuclides. • Provide a means of explaining alpha and beta decay and the com parison of half-lives with relative in stabilities, the latter being important because of the increasing use of radio isotopes as research tools in all branches of chemistry and related fields. Going from the practical to particu lar areas, nuclear phenomena may be related, or presented as a foundation, germane to the development of con ventional chemical concepts, Dr. Ca retto adds. For example, in mass-en ergy relationships, a simple applica tion of Ε = MC 2 for a simple chemical reaction, such as H 2 + V 2 0 2 = H 2 0 , compared with a nuclear reaction, such as H i + η = H 2 , serves to illustrate the relative magnitudes of the energy 48 C&EN SEPT. 16, 1968
in both cases, the nature of the chemi cal (coulombic) force as compared to the nuclear, and the origin of the chemical term—heats of reaction. As to the manner in which nuclear ideas might be introduced in under graduate chemistry courses, Dr. Thomas T. Sugihara of Texas A&M University breaks down the introduc tion of various topics into three gen eral classes: • Phenomena which are quite gen erally discussed in chemistry courses and which are concerned with a nu clear property or may be, in part, a nuclear process. In such discussions, adequate treatment of the phenome non surely requires consideration of the nuclear property or process. For example, a description of the interac tion of a nuclear magnetic moment with an external magnetic field in NMR is hardly comprehensible unless the student knows some of the proper ties of nuclei. • Topics in which a nuclear exam ple might be the most interesting or most illuminating way of getting an idea across. A universally used exam ple to demonstrate barrier penetration is alpha decay, Dr. Sugihara points out. Other examples, he goes on to say, include: Nuclidic masses to clearly reveal mass-energy equiva lence; positronium or muonium may well prove as helpful as the hydrogen atom in solving the Schrodinger equa tion for a coulomb potential; the wave character of particles is illustrated by neutrons as well as electrons; radioac tive decay is commonly used to show the first-order rate law in kinetics. • The final class, Dr. Sugihara points out, alludes to the basic notion that too often chemistry students get the idea that the principles, theories, laws, and the like, which they are learning apply only to electrons or perhaps to atoms and molecules. For example, he adds, in many text books, one can find statements such as "no two electrons can have all their quantum numbers, including spin quantum number, the same." From this statement one might conclude that the Pauli principle is concerned only with electrons, Dr. Sugihara says. As this would be an erroneous conclu sion, the fact that the principles of chemistry do embrace nuclei should be stressed and discussed where rele vant. The degree to which nuclear con
cepts are introduced into freshman courses will vary from school to school. Accordingly, the depth of study will vary also. However, regardless of the extent, there are some unique as pects of nuclear and radiochemical phenomena when incorporated in gen eral chemistry demonstrations. According to Prof. Rolfe H. Herber, of Rutgers University, New Bruns wick, N.J., these unique aspects in clude:
Stimulation of student
interest:
Despite the fact that the atomic age is more than 25 years old, nuclear phe nomena still have associated with them a considerable amount of glamour and newness. This can be used to generate and enhance student interest. Broad utilization of equipment: In many instances, the same basic equip ment can be used in a number of dem onstrations. Accordingly, the students rapidly become familiar with the func tions of various "black boxes." Quantification of amounts: The detection of individual decay events makes it possible to obtain numerical data related to the quantity of a chem ical substance which is present. As progress is made up the ladder of the undergraduate curriculum, questions are often raised in the use of problems involving nuclear and radiochemistry in introducing undergradu ates to the methods of research. Dr. James W. Cobble of Purdue University responds to such questions by saying that due to the wide variety of techniques involved, the methods of research in radio and nuclear chemis try perhaps offer certain advantages over conventional methods. For example, Dr. Cobble points out, an undergraduate working in nuclear fission studies will very likely en counter heavy-element chemistry, ele ment chemistry, electrode position, rare-earth and transition element chemistry, inorganic separations to a high degree of sophistication, and many other techniques. As to how, when, where, and how much relative to the inclusion of nuclear concepts, there are no clearcut answers, the educators point out. However, they generally agree to and argue for a modest coverage of nu clear topics in undergraduate chemis try courses. If for no other reason than that the diversity of chemistry as an intellectual discipline should not be hidden from the students.
