1.3. Quantum numbers and quantization of matter

Quantization is the concept that matter, particles, and other physical quantities, such as charge, energy, and magnetic spin, can have only certain countable values. These certain countable values can be either discrete or continuous variables. Discrete values are defined as countable in a finite amount of time. Continuous values are defined as countable in an infinite amount of time. Whether or not a quantum system is discrete or continuous depends on the physical system or the observable quantity.

We will discuss the particles that are most associated with quantum chemistry: protons, neutrons, electrons, and hydrogen atoms. The neutrons and protons comprise the nucleus of atoms and are held together by the strong nuclear force, and they do not have a measurable angular momentum quantum number within the nucleus. In contrast, free protons and neutrons not bound within a nucleus can be in motion and then possess an angular momentum...