Two daunting questions face the authors of prospective textbooks. (1) For whom is the book intended? (2) What makes it different from other books intended for the same audience? We first address these questions.

One might think from counting the mathematical equations that the book is intended for a theoretical physicist. This is partially true, for indeed we hope the subject is presented in a way that will satisfy a rigorously inclined mathematical physicist that “valency and bonding” is not just murky chemical voodoo, but authentic science grounded in the deepest tenets of theoretical physics.

Beyond Chapter 1 the reader may be relieved to find few if any equations that would challenge even a moderately gifted high-school student. The emphasis on orbital diagrams and “doing quantum mechanics with pictures” might then suggest that the book is intended for undergraduate chemistry students. This is also partially true. For example, we believe that our treatment of homonuclear diatomic molecules (Section 3.2.9) should be accessible to undergraduates who commonly encounter the topic in introductory chemistry courses.

Our principal goal has been to translate the deepest truths of the Schrödinger equation into a visualizable, intuitive form that “makes sense” even for beginning students, and can help chemistry teachers to present bonding and valency concepts in a manner more consistent with modern chemical research. Chemistry teachers will find here a rather wide selection of elementary topics discussed from a high-level viewpoint.