Inorganic Chemistry

Gary Wulfsberg

Preface

This textbook is intended for the undergraduate or introductory graduate Inorganic Chemistry course or sequence of courses, such as the one-semester junior-senior level Advanced Inorganic Chemistry course.  It is intended to fill the gap between advanced inorganic textbooks that are encyclopedias of chemical reactions and those that are mainly textbooks of theoretical or physical inorganic chemistry.  It covers virtually all topics suggested for the core inorganic requirement for a professional chemistry degree by the American Chemical Society Division of Inorganic Chemistry Ad-hoc Subcommittee.[i]

The text is divided into two parts.  Part I of the text, "Inorganic Ions and Simple Molecules in Chemistry and in our Environment," corresponds approximately to the first third of most advanced inorganic texts, but differs in that the chemical concepts and reactions of Part I can be explained using Valence Bond theory, so that it is accessible to students who have had only general and organic chemistry courses.  Part II of the text, "Inorganic Substances and Materials:  Theory and Applications,” includes the remainder of the topics that are standard for an Advanced Inorganic course:  symmetry, Molecular Orbital theory, materials chemistry, organometallic chemistry, bioinorganic chemistry, inorganic reaction mechanisms.  This part of the text is at a more advanced level appropriate for students who have had physical chemistry.

Use of The Text in One-Semester Advanced Inorganic Chemistry Courses.

We anticipate that most junior-senior level Advanced Inorganic students will be able to go quickly and selectively through Part I, and will spend most of their time in Part II, which we discuss first.[ii]  Part II begins with chapters introducing the theoretical tools (symmetry, group theory, molecular orbital theory) needed for advanced study.  Chapter 10 on Molecular Orbital theory is designed to help students visualize molecular orbitals in important classes of molecules and materials, including cluster compounds and even bulk metals.  This chapter is then immediately followed by chapters in which Molecular Orbital theory can be applied and reinforced extensively:  Chapter 11 on transition-metal organometallic chemistry; Chapter 12 on the elements and their clusters.

Chapter 12 begins a sequence of chapters (12 on the elements; 13 on oxides; 14 on halides, nitrides, and sulfides; 15 on hydrides) that deal with the important area of inorganic materials.  These are introduced by key sections (12.1, 12.2, 13.1, 14.1) which help a student understand why (and even to predict whether) some compounds (e.g., SiO2, TiO2 and ReO3) have extended structures that make them of potential interest as materials or in geochemistry, while others (e.g., SO2 and OsO4) have molecular structures and are therefore important in other areas of chemistry (e.g., environmental chemistry).  In each chapter, different sections compare and contrast the physical and chemical properties and uses of the molecular compounds with those of the macromolecular materials, giving students a good picture of the importance of overall structure on properties and uses. 

In order to stimulate student interest early in the course, other interesting applications of the principles of inorganic chemistry are integrated throughout the textbook, rather than leaving them confined to the back of the book.  The subheadings of the chapters suggest the locations of these applications:  environmental, geological, and aquatic inorganic chemistry appear in Chapters 3-6, 13, and 16; bioinorganic and medicinal inorganic chemistry and chemical safety are found in Chapters 5, 6, 8, 11, 16, and 17.  Mechanisms of reactions are likewise discussed to varying degrees throughout the text, most prominently in Chapters 8, 9, 11, 12, 16, and 17.  It is likely that students have had enough background in mechanisms in their organic course, and in kinetics in their physical chemistry course, to follow the mechanisms in the earlier chapters, but if not, the main chapter on kinetics and mechanisms, Chapter 16, can easily be moved to an early position in Part II of the text.

Part I

In this textbook, Part I contains topics that can be understood without using Molecular Orbital theory; a one-semester advanced inorganic course may include at least some of these topics, particularly those in Chapters 1 (periodicity of fundamental atomic properties) and 8 (Transition Metal Complexes).  Chapter 8 can be placed after Chapter 10 if the instructor wishes to make use of symmetry and molecular orbital theory in developing the ligand field theory for transition metal complexes.

Chapters 2-7 include reviews and extensions of topics covered briefly in General Chemistry and then developed further in the early parts of most Advanced Inorganic texts.  The fact that these chapters are written to be understood without a prior mastery of physical chemistry or molecular orbital theory means that they can be covered relatively quickly.  Students who have had physical chemistry but nonetheless need further study of certain topics likely can do this on their own outside of class time; we believe that the many applications in environmental and medical fields found in Part I will interest these students enough so that they will do this.  Students have commented to me that Part I helps them actually understand procedures that were learned by rote in General Chemistry; it is thus especially valuable for beginning graduate students who aspire to teach General Chemistry. 

Much of the inorganic chemistry needed by analytical chemists, biochemists, industrial chemists, and environmental chemists is reaction chemistry of simple ions in aqueous solution, which can be treated quite well without the use of advanced bonding concepts.  Aqueous reaction chemistry and its periodicity have traditionally been given very inadequate treatment in freshman chemistry (often being omitted for lack of time), while being omitted as well from Advanced Inorganic texts.  A major goal of Part I of this text is to give this important area its due, while improving the presentation over the traditional deadly dull march through the groups of the periodic table.  Instead, inorganic reactivity is organized by familiar broad categories:  acid-base reactivity in Chapters 2 and 3, precipitation processes in Chapter 4, complexation in Chapter 5, and redox chemistry in Chapter 6.  In each chapter, general principles are developed which allow the student to classify reactive ions (and simple molecules) and then predict and explain how reactive they will be in the type of reaction under discussion.  This organization was widely acclaimed when first presented in the author's earlier Principles of Descriptive Inorganic Chemistry (University Science Books, 1991), to which Part I of this text is closely related.  The student who can apply and extend the principles of aqueous reactivity from Part I of the text will also gain several new insights into the more advanced chemistry covered in Part II, such as the chemistry of inorganic materials.

A number of new references and pedagogical improvements have been incorporated in the other partially-reorganized chapters of Part I; perhaps the most notable of these is the introduction of redox predominance diagrams in Chapter 6 as a visual representation of standard reduction potentials which also helps the student build up to the use of the more complex E°/pH or Pourbaix diagrams for redox chemistry.

Other Uses of This Text

This book is structured with an ascending level of difficulty as it progresses from Part I to Part II.  This organization should allow it to be especially useful in international settings which have the tradition of teaching some inorganic chemistry each year of the undergraduate curriculum, and is ideal for those American schools having both a "sophomore" and a senior-level inorganic course.

Many teachers with introductory inorganic chemistry courses are finding these to be populated more and more by students from a variety of fields--geology, environmental science, industrial chemistry, materials and polymer science, metallurgy, chemical safety, medicinal chemistry, molecular biology--who are finding that their field involves inorganic materials and reactivity.  Part I of this textbook emphasizes the fundamentals of inorganic chemistry that these students can use, for example, to anticipate and prevent new environmental problems, not just react to known ones.  Such a course can develop a substantial enrollment as a valuable part of a chemistry minor.  Optional sections at the ends of chapters (indicated by stars) may readily be omitted for these students.

If the inorganic chemists at a university want to tap into the market for an introductory inorganic chemistry courses serving chemistry minors from allied sciences, we might suggest that this course, using Part I of this text, also be available as an elective for majors; the applications of inorganic chemistry are also subjects that chemistry majors find fascinating and rewarding to study, and such study will prepare these students for the growing opportunities for interdisciplinary collaboration with the allied sciences.  Having one text with a consistent approach for both courses would serve as a financial and intellectual incentive to students from each course to consider taking the other. 

Another possible usage is at universities which have a rigorous freshman-level course for chemistry majors which is intended to include significant coverage of descriptive inorganic chemistry.  In such a course, Part I could be begun at the freshman level,[iii] then the textbook kept for later use in the Advanced Inorganic course.

Other Aids to Learning

 The text has an unusually large selection of challenging practice exercises (about 40 to 70 per chapter); each chapter also has several worked-out examples and a list of concepts or study objectives.  Exercises that are starred (*) have answers provided in Appendix B at the back of the book; the answers to the other exercises are provided in the Instructor's Manual available from the publisher.

The most basic level of understanding of phenomena of inorganic reactivity is the observation of them.  In Appendices A.1-A.7 we present several optional simple inorganic experiments appropriate for use in Part I in which students not only observe trends in inorganic reactivity, but are challenged to reason inductively from them to discover for themselves many of the main principles of the text.  These technically simple experiments include asking the student to design parts of the procedure, in which they must understand how to control multiple variables--these experiments are practice in the scientific method of a sort not normally encountered until students do research.[iv]  In courses which do not have laboratories, these can be done as demonstrations followed by discussion among small groups of students to try to design the procedure and reason inductively to the principles which they discover.  To make these more easily performed and more widely available, videos of two of these demonstration/discussions have been prepared.[v]  Other useful videodisc and other computer simulations of inorganic reactivity and its trends are also becoming more available.[vi]  If the course does have a laboratory, or for Advanced Inorganic laboratories, the instructor will want to add traditional synthesis and characterization experiments, such as those found in the laboratory manual by Girolami et al.[vii].

Acknowledgments

 I am much indebted to the following reviewers who provided useful and insightful comments on the manuscript: Robert Angelici, Roger DeKock, Art Ellis, Walther Ellis, Harry Gray, James Penner-Hahn, William Robinson, Alan Stolzenberg, William Trogler, David Tyler, and David Westmoreland.
            I also wish to thank William Ilsley for class-testing and error-checking the manuscript, thus providing an invaluable supplement to the author's own class-testing of almost all of the chapters of this manuscript.  Users of this text are encouraged to contact the author by e-mail (wulfsberg@mtsu.edu) about errors they find or with suggestions; I wish to thank such helpful readers in advance.  I also wish to thank Pekka Pyykkö, John Verkade, Clark Landis, Preston MacDougall, Martin Stewart, and Judith Iriarte-Gross for helpful suggestions related to their areas of specialization.  I am also indebted to Barry Farris, Michael Kearney, Paul H. Wulfsberg, Joanna Wulfsberg, Candace Stacey, Lisa Campbell, and Jennifer Watkins for assistance in proofreading and clerical chores, and Middle Tennessee State University for providing released time to work on the research for the manuscript.


NOTES

[i]  These are listed by J. G. Verkade, J. Chem. Educ., 68, 911 (1991), Table 2.

[ii]  We have had many students begin their use of this text with Part II; this has caused them no difficulties.

[iii]  In this case some of the more theoretical parts of Chapter 1 should be postponed until the Advanced Inorganic course.

[iv]  See also G. Wulfsberg, J. Chem. Educ., 60, 725 (1983).  We do not recommend doing all of these experiments, but doing only enough for the students to develop the ability to reason inductively and design a sound scientific experiment themselves.  We have found that our students, even the seniors, usually do not understand how to design an experiment in which two variables must be controlled.

[v]  Lyubov V. Hoffman, M.S. Thesis, Middle Tennessee State University, 1996.  Faculty who adopt this text may obtain copies of the video forms of Experiments A.1 and A.6 from the author by writing the author on letterhead stationery (Box 405, Chemistry Department, Middle Tennessee State University, Murfreesboro, TN 37132) and sending him two blank videocassette tapes.

[vi]  A useful device for some observations is the KC-Discoverer videodisc bank of pictures of reactions of the elements (A. Feng, J. W. Moore, W. Harwood, and R. Gayhart, J. Chem. Educ.: Software, 1B, 1 (1988);Many of the principles of Part I of this text have been incorporated into the program PIREXs (Predicting Inorganic Reactivity Expert System) (J. P. Birk, J. Chem. Educ.: Software, 3B, No. 1, Disks 1-3 (1990); see also J. P. Birk, ACS Symp. Ser. 408 (Expert System Applications in Chemistry), 20 (1988); J. P. Birk, J. Chem. Educ., 69, 294 (1992).  Birk has also developed an adjustable computer version of the Pourbaix diagrams of Chapter 6 which allows the student to superimpose the diagrams of two potentially-reacting species; this is also expected to be published in  J. Chem. Educ.: Software.

[vii]  G. Girolami, T. Rauchfuss, and R. Angelici, Synthesis and Technique in Inorganic Chemistry, 3rd Edition: Sausalito, CA, University Science Books, 1999.