The way in which electrons are arranged around a nucleus and the effect that this has on chemical behavior are the subject of the next chapter.

At the moment, notice only the trend from metals, to nonmetals, to an inert gas, and the beginning of a repetition of properties with the inert gas neon and the soft metal sodium.

Chemical properties are periodic functions of the atomic number - in a listing of elements by increasing atomic number, similar properties are encountered again and again at regular intervals.

This is one of the most important generalizations in chemistry.