The purpose of this study was to investigate Grade 12 students' understandings of the nature of chemical bonds and energetics elicited across five familiar chemical reactions following a course of instruction. Based on a chemist's analysis of the conceptual area, a list of relevant concepts involved was identified, and the range of five reactions was chosen. These then served as the framework for drawing up a semistructured interview protocol, which was administered to 48 students. The students' responses revealed a range of conceptions at variance with the chemist's view, some of which have not yet been reported in the literature. The implications of the research are that grasping chemistry concepts and principles from the students' perspective is full of pitfalls. There are numerous ways in which students can misconstruct concepts and principles. Teachers, curriculum developers, and textbook writers must be aware of the various ways in which material presented could be misconstrued and hence be a hindrance to student learning. © 1998 John Wiley & Sons, Inc. J Res Sci Teach 35: 569–581, 1998.