If you look at any chemistry textbook, you will see Lewis structures introduced long before electronic and molecular geometries. This makes sense since you need Lewis structures to determine molecular geometry. Unfortunately, research has shown that students often do not recognize that the purpose of drawing Lewis structures is not to create the structure itself but to use it as tool to understand the properties of the molecule (Cooper, Grove, Underwood & Klymkowsky, 2010).
First, I would like to thank all those who commented on my last blog. For the record, I was wrong. Initially I looked at Linus Paulings early papers as he worked on electronegativity. Much of the work focused on connecting the concept to bond energy. There were some great comments posted to the blog. Probably one of the best was explaining how the concept of electronegativity presents a model for bonds. It is not an observable quantity. This really helped me explain it better to my students. As the commentor posted, all models have limitations. Second, the person commented that in Linus Pauling's General Chemistry book published in 1970 (Dover Publishing) that he does indeed talk about the differences in electronegativity to discuss a type of ionic and covalent character. I stand corrected.
Most chemistry teachers somehow teach Lewis dot structures. These structures are the foundation for VSEPR theory, three dimensional models and ultimately how the structure allows us to predict what happens on a large scale. Here is the crazy part...there are a number of different "rules" that really do not make a whole lot of sense. Do a quick search...everyone has there own rules.