This paper from Chemistry: A European Journal by Manolis Manos and Mercouri Kanatzidis (link provided below in Web Resources) describes the ion-exchange chemistry of a layered sulfide (KMS-1) that exhibits an enhanced preference for soft metal cations (Cd2+, Pb2+, and Hg2+) replacing K+ in between the metal sulfide layers of KMS-1. Not only does this paper provide a practical application of hard-soft acid-base theory (HSAB), but it provides an accessible introduction to the technical literature for undergraduates, particularly at the first or second-year level. This learning object was used to illustrate hard-soft acid-base theory, the structures of extended solids, solid solution formation, ion-exchange chemistry, and the analysis of structural changes by X-ray powder diffraction.
Students in a second-year inorganic chemistry course were asked to read this paper in preparation for a class discussion (see further details in implementation notes). For many students, this was a first or second exposure to reading the primary literature.
After reading and discussing this paper, a student will be able to:
• Articulate the underlying problem and motivations driving the research presented in the paper
• Explain the collection of experimental data that lead to figures and tables presented in the paper and describe the interpretation of these results by the authors
• Discuss the relative importance of various thermodynamic factors predicting the favorability of ion-exchange reactions
• Gain confidence reading a paper from the primary literature in inorganic chemistry
Students in a second-year inorganic chemistry course read the paper "Sequestration of Heavy Metals from Water with Layered Metal Sulfides" prior to a class discussion. The pdf file was posted to the course Moodle, and students were asked to “Annotate” their copy (either in printed or electronic form) to highlight terms or sections of text that they did not understand. At the end of the class discussion, they turned in either a printed or an electronic copy of the annotated paper.
A series of questions that I used to guide the discussion are attached below as a Word document. While I typically give out these types of discussion questions in advance and ask students to answer them prior to the discussion, in this case I did not. The timing of this literature discussion immediately followed an exam, so I was just wanted to ensure that students had read the paper prior to our class discussion. Making them turn in the annotated copy of the article was generally successful in achieving that outcome.
A second Word document is attached below containing the list of unfamiliar terms that were marked as unfamiliar by my students. Most of these terms were highlighted by the majority of the class. In some cases, I explained the meaning of the term in the course of our discussion, for example energy dispersive spectroscopy, but in other cases, the concepts were not central for a basic understanding of the paper and we never addressed them.