(BQ) Part 2 book "Physical chemistry" has contents: Free energy and chemical potential, introduction to chemical equilibrium, equilibria in single component systems, equilibria in multiple component systems, electrochemistry and ionic solutions, introduction to quantum mechanics,.and other contents. | 12 Synopsis Spin The Helium Atom Spin Orbitals and the Pauli Principle Other Atoms and the Aufbau Principle Perturbation Theory Variation Theory Linear Variation Theory Comparison of Variation and Perturbation Theories Simple Molecules and the Born-Oppenheimer Approximation Introduction to LCAO-MO Theory Properties of Molecular Orbitals Molecular Orbitals of Other Diatomic Molecules Summary Atoms and Molecules W E HAVE SEEN HOW QUANTUM MECHANICS provides tools for understanding some simple systems, up to and including the hydrogen atom itself. An understanding of the H atom is a crucial point because it is real, not a model system. Quantum mechanics showed that it can describe the hydrogen atom like Bohr’s theory did. It also describes other model systems that have applications in the real world. (Recall that all of the model systems—particle-in-a-box, 2-D and 3-D rigid rotors, harmonic oscillators— could be applied to real systems even if the real systems themselves weren’t exactly ideal.) As such, quantum mechanics is more applicable than Bohr’s theory and can be considered “better.” We will conclude our development of quantum mechanics by seeing how it applies to more complicated systems: other atoms and even molecules. What we will find is that explicit, analytic solutions to these systems are not possible, but quantum mechanics does supply the tools for understanding these systems nonetheless. Synopsis In this chapter, we will consider one more property of the electron, which is called spin. Spin has dramatic consequences for the structure of matter, consequences that could not have been considered by the standards of classical mechanics. We will see that an exact, analytic solution for an atom as simple as helium is not possible, and so the Schrödinger equation cannot be solved analytically for larger atoms or molecules. But there are two tools for studying larger systems to
