We describe the logical flaws, experimental contradictions, and unfortunate educational repercussions of common student misconceptions regarding the shapes and properties of lone pairs, inspired by overemphasis on “valence shell electron pair repulsion” (VSEPR) rationalizations in current freshman-level chemistry textbooks. VSEPR-style representations of orbital shape and size are shown to be fundamentally inconsistent with numerous lines of experimental and theoretical evidence, including quantum mechanical “symmetry” principles that are sometimes invoked in their defense. VSEPR-style conceptions thereby detract from more accurate introductory-level teaching of orbital hybridization and bonding principles, while also requiring wasteful “unlearning” as the student progresses to higher levels. We include specific suggestions for how VSEPR-style rationalizations of molecular structure can be replaced with more accurate conceptions of hybridization and its relationship to electronegativity and molecular geometry, in accordance both with Bent's rule and the consistent features of modern wavefunctions as exhibited by natural bond orbital (NBO) analysis.

An instructional unit is described for integrating computational molecular modeling into the undergraduate organic chemistry laboratory curriculum. The approach emphasizes use of computational modeling as a readily available, efficient tool for understanding structure and reactivity, predicting products, and rationalizing the results of organic reactions performed in the laboratory. This approach has been used in a large organic chemistry lab program for five semesters with favorable results. Through individual hands-on experience with computational modeling, students gain a more complete and correct understanding of structure, bonding, and reactivity.

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This article outlines the recent transformation of an intermediate undergraduate organic synthesis laboratory course at the University of Wisconsin–Madison. This course has had a unique design for over 30 years, with structured experiments performed in the teaching laboratory only for the first half of the course. In the second half of the course, students are assigned to projects in graduate research laboratories. The classroom component of the course, however, did not provide students with many of the skills essential for success in the research laboratory. Over the academic years 2003–2005, we systematically changed the classroom and laboratory components of this course so that it now provides experience using modern chemistry experimental techniques and chemical information resources, instruction in scientific writing and the use of chemical drawing software, and awareness of basic scientific ethics. Here, we outline our rationale behind each course component change, describe how the changes were implemented, and discuss how the effects on student learning were assessed. Overall, these changes have been greeted with enthusiasm by our students, faculty, and staff, and we believe this course provides a curricular model exportable to other chemistry departments.