So far, the focus in this book has been mostly on electrons. That is normal because electrons are important like nothing else for the physical properties of matter. Atomic nuclei appear in the story only as massive anchors for the electrons, holding onto the electrons with their positive electric charge. But then there is nuclear energy. Here the nuclei call the shots. Nuclei are discussed in this chapter.
The theory of nuclear structure is much less advanced than that of the electronic structure of atoms. Unlike the electromagnetic forces, the nuclear forces are very poorly understood. Examining them with well-understood electromagnetic probes is limited since nuclear forces are extremely strong, resisting manipulation. Accurate direct measurement of quantities of interest is usually not possible.
Nuclear physicists responded to that with a tidal wave of ingenious experiments, usually leveraging one accepted fact to deduce the next one (and at the same time check the old one). Much of this data is presented in this chapter in the form of overview figures. This is intended to allow you to understand the big picture.
Some important approximate quantum models have been developed by nuclear physicists to explain all that data. This chapter also tries to explain these models in relatively simple terms.
The first few sections of the chapter give an overview of key concepts important for understanding nuclei. It is highly recommended that you read these before reading any later sections in this chapter.
But first one word of caution about the figures. Most of their data has been carefully machine-read from standard nuclear data bases. However, the used data bases date from around the year 2003. So check any data you get from the figures for any more recent updates that may be available. Also note that various figures that depend on relatively delicate mathematical analysis were machine produced too. Typically this was done using reasonable simplifications and/or a priori assumptions. Use such figures to understand the big picture, but do not pick individual data from them without checking it. A simple automated procedure processing about 3 000 different nuclei from some key data using an approximate model cannot compete with a nuclear specialist analyzing a single nucleus based on all the extensive knowledge that is available for that one nucleus.