In the Classroom
Revised First-Year Curriculum with an Inorganic Chemistry Course
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Kenneth M. Long Department of Chemistry, Westminster College, New Wilmington, PA 16172;
[email protected] For many years Westminster College offered a traditional, modern, full-year, general chemistry course. Because of faculty dissatisfaction with the usual laboratory programs, the lab was converted to a more investigative approach as a first step in improving the course, making it into a real scientific experience (1, 2). Students acquire data and observations of chemical systems and propose logical explanations before the systems are studied in the classroom. Two long-continuing problems were not affected by these changes in the laboratory. The first problem was that some students were bored with the first semester of general chemistry. Things sounded familiar and these students thought that they understood it without doing much work.1 The second problem was that other students did not seem to have the tools to be successful in a course designed for science majors. Many in this group lacked mathematical and problem-solving skills and also lacked an understanding of the basic chemical concepts that colleges expect students to learn in high school chemistry. Finally, a third problem was that the faculty decided that there was not enough inorganic chemistry in the traditional first-year course. A survey of college general chemistry courses indicated that nationally an average of only 7.8% of the time in such courses was devoted to descriptive chemistry (3). To satisfactorily meet the guidelines of the ACS Committee on Professional Training (4), a new course was needed earlier in the curriculum. New Curriculum The faculty decided to become agents of change (5). Three new courses were designed and first taught in 1996– 1997: Principles of Chemistry for the “bored” students, followed by The Chemistry of the Elements, an inorganic course; and Foundations of Chemistry for those students who were not prepared for the Principles of Chemistry course. All students who have had a high school chemistry course take a placement test. Those with acceptable scores are assigned to the one-semester Principles of Chemistry course. Those with low scores are assigned to Foundations of Chemistry. Those with intermediate scores are allowed to chose their entry level, in consultation with their academic advisors. Foundations of Chemistry In Foundations of Chemistry, students are introduced (or reintroduced) to the basic concepts of chemistry: measurement, energy, atoms, formulas, reactions, stoichiometry, bonding, states of matter, and solutions. Students who successfully complete the Foundations course are now able to succeed in Principles of Chemistry.
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Principles of Chemistry Students in Principles of Chemistry initially review stoichiometry, atomic structure, and bonding. Most of the course, however, is devoted to nuclear chemistry, equilibrium, kinetics, thermodynamics, and electrochemistry. In this course, students soon realize that they are not repeating their high school chemistry and are challenged by the concepts and problems. Students who successfully complete Principles of Chemistry are eligible to enroll in Chemistry of the Elements.2 This course utilizes the principles learned in the previous course to understand inorganic chemistry. Chemistry of the Elements Most general chemistry texts include an introduction to the chemistry of the transition elements late in the book and this topic is frequently omitted. To emphasize that this is a different course, Chemistry of the Elements begins with study of the transition elements. Here the students learn about the structures of coordination compounds and how to use the crystal field model to rationalize the properties of these materials. After consideration of factors affecting the stability of the compounds, they focus on applications of coordination chemistry in areas such as detergents and bioinorganic chemistry. To introduce students to solid state chemistry, they build models of metal lattices and lattices of some simple ionic compounds. These ideas are then utilized to examine a number of inorganic solid-state structures, including some defect structures. This segment concludes with study of the energetics of the solid state, using Born–Haber cycles. To emphasize that the bases of the periodic law and the periodic table are the chemical and physical properties of the elements, students spend three weeks in the lab investigating periodic trends in periods and families. In class they then learn a network of ideas that can be used to understand the trends (and anomalies) they have observed. The periodic table becomes an organizing principle for the course (6). Class work on a family begins with a look at a table of properties of the elements in the family. Students are asked to use their knowledge of atomic structure and the periodic law to explain both observed trends and anomalies in trends, for example, the alternation of electronegativity values in the boron family. In class, students are also concerned with the uses of the elements and their compounds in everyday life. In the laboratory all data and observations are recorded in a bound notebook. On occasions when students need to share lab data, they utilize the campus network to share it electronically. All reports are written in the notebook or printed with a word processor.
Journal of Chemical Education • Vol. 80 No. 10 October 2003 • JChemEd.chem.wisc.edu
In the Classroom
Conclusions
Notes
Student evaluations of the courses have been positive. Students like learning something different from their previous experiences. They particularly like opportunities to investigate systems by methods they devise without specific directions from an instructor or laboratory text. Making these changes has allowed the senior-level inorganic course to become a truly advanced course since descriptive chemistry is now primarily in the first-year course. Time is now available for chemical applications of group theory and for more advanced treatment of spectra and magnetic properties than before. More advanced treatment of boranes, kinetics and reaction mechanisms, organometallic compounds, catalysis, and bioinorganic chemistry has also become possible (7). The chemistry faculty are pleased with these changes. A larger fraction of our students are successful in first-year chemistry and go on to further success in subsequent courses. W
Supplemental Material
More detailed descriptions of each of these courses are available in this issue of JCE Online.
1. Many of these students were shocked to discover halfway through the semester that they were facing a rather poor grade. 2. Students majoring in chemistry, environmental science, or physics, plus students preparing for admission to a professional school in the health sciences are required to take Chemistry of the Elements.
Literature Cited 1. 2. 3. 4.
Barrow, G. M. J. Chem. Educ. 1994, 71, 874–878. Herman, C. J. Chem. Educ. 1998, 75, 70–72. Taft, H. L. J. Chem. Educ. 1997, 74, 595–599. Undergraduate Professional Education in Chemistry: Guidelines and Evaluation Principles, American Chemical Society Committee on Professional Training: Washington, DC, 1999; pp 6–9. 5. Lagowski, J. J. J. Chem. Educ. 1996, 73, 599. 6. Woodgate, S. D. J. Chem. Educ. 1995, 72, 618–622. 7. Pesterfield, L. L.; Hendrickson, C. H. J. Chem. Educ. 2001, 78, 677–679.
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