5. Gain and Loss of Electrons   Previous PageNext Page

The animation shows the essence of salt structure: positive and negative ions, attracted toward one another, and packed in a regular, geometric array into a three-dimensional solid with an alternation of positive and negative charges.

By contrast, in a metal all of the ions are positive ions, and these are held together by a sea of mobile electrons. We shall see how the arrangement of ions and electrons in these two kinds of solids makes each behave in its own way.


The ideas of periodicity of chemical behavior and of a periodic table with horizontal rows corresponding to electron shells were introduced at the end of Chapter 3.

These second-shell (or second-row) elements, Li to Ne, are a microcosm of the entire periodic table, for the trends and behavior that we will see in this chapter will be encountered again with the heavier elements.

We are learning not only about the second-shell elements, but about the basic principles of chemical behavior that are applicable to all atoms. These principles appear in a particularly simple way for the second-shell atoms.

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