Christian Hardtke
    Department of Biology
    christian.hardtke@mcgill.ca
William C. Galley
    Department of Chemistry
    william.galley@mcgill.ca
Gregory Brown
    Department of Biology
    gregory.brown@mgill.ca
    
Main
Introduction
Student Comments
Online Seminar
Fritz Lipmann
The High-Energy Phosphate
Caveats
Semantics
Bond Making & Breaking Tutorial
Hydrophobic Bonding
EXBAN Supporters
Research on Misconception
References
 
Contact Us
 
   

Introduction

Over a span of several years more than 600 biological science students, entering an introductory physical chemistry, have been questioned on their knowledge of the energetics of bond breaking and making. Seventy five percent of the students consistently indicate that reactions are exothermic as a result of bond breaking. When these students are questioned specifically about the high energy phosphate bond in ATP, this number rose to 90%. The notion of exothermic bond breaking persists among students in that they are misinformed at the high school, junior college and university levels in chemistry, as well as in biology courses, as to the nature of the bond breaking and forming process. Further support for the exothermic bond breaking misconception appears in the form of abbreviated and incorrect descriptions of the process in texts that these students would have encountered. This site is dedicated to examining and correcting the persistent and widespread misconception that energy release results from the rupture of covalent bonds.

This EXBAN site permits the user to link to a publication in the Journal of Chemical Education, and/or a seminar online, that provide the survey data for student belief in this decades-old exothermic bond breaking misconception. These data are supported by a list of student opinions as to where in their learning, they felt there were led astray or became confused, about the energy changes associated with the formation and rupture of covalent bonds. Chemistry teachers at all levels, particularly those who are unfamiliar with molecular aspects of biology, are very often unaware that a significant fraction of the students in their classes, even in the upper undergraduate years, believe that bond breaking is an exothermic process, or are at best confused on the issue. One aim of the present site is to create awareness among those teachers as to why students often have chemistry turned upside-down, when it comes to considering energy changes. The EXBAN site is also directed toward those students, particularly in the biological sciences, who either believe in the exothermic bond breaking misconception in general, or that molecules behave differently in biology and chemistry. It is hoped that students who are directed to this site will become aware of the magnitude of the confusion with regard to this issue that exists in the classroom and in textbooks. It is anticipated that by working through the materials presented here including on the history of the "exothermic bond breaking misconception" (Fritz Lipmann, high energy phosphates), and by running through the program in which the energy changes associated with bond breaking and making, can be followed in a graphic manner, much of the confusion centered around topics involving, for example, the energy flow in the cell, will be eliminated. The quotation below from Franklin M. Harrod's book, "The Vital Force, A Study of Bioenergetics", published in 1986 alludes to the widespread and long-standing nature of the confusion surrounding the nature of the terms "energy-rich phosphates" and the "high energy phosphate bond", in the minds of students:

"The term 'energy-rich' phosphates was to prove unfortunate misleading generations of beginning students (including this author) who understood it to imply some special kind of bond that releases energy when broken. In fact, energy must be expended to break a bond, and phosphate compounds are no exception."

Our recent surveys of undergraduates suggests that the problem is now even more widespread than that suggested in this quote in that the "exothermic bond-breaking" misconception is not restricted to the "high energy phosphate bond". However, our experience indicates that when students are made aware of the rampant nature of the misconception and are reminded of the basis of the energy changes associated with chemical and biochemical reactions, they themselves become more careful in their reading and critical of what they encounter in texts and lectures.

Finally, this EXBAN website is directed to teachers who teach the "exothermic bond breaking" misconception and to authors who present it in textbooks. It is evident both from students and from personal experience, that exothermic bond breaking is taught not only in the biological sciences, but in chemistry at the introductory levels as well. It is hoped that teachers in these areas of science teaching will become acquainted with this website and references that are contained here, and as a consequence contribute to harmonizing the teaching of energy changes associated with molecular processes in chemistry and biology. Students treat what they are taught in the classroom and read in textbooks, as fact. The brief descriptions and semantics that are employed, in particular in introductory biology texts, contribute in no small way to the confusion that exists in this area. In other cases, incorrect descriptions appear which clearly reveal that the author(s) prescribe to the exothermic bond breaking myth. Included in an accompanying list that contains caveats alerting the reader to the potential for confusion in the consideration of "high energy phosphates". The user will find a page (high energy phosphates) devoted to texts that have over the years, considered the problem in greater detail.

We hope the user finds this EXBAN site informative and useful. Comments on its contents and suggestions for improvement are welcomed (contact us). Users who have struggled with the "exothermic bond breaking" misconception over the years, as well as others who would like to offer their support for our efforts to correct this misconception, may want to over advice, and/or add their names to a list of EXBAN SUPPORTERS. W.C.G is grateful to Prof. Todd Silverstein for drawing attention to typographical errors and for his suggestions for improvements in clarity in the website.

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2005 McGill University