1. Ch. 7.2 Ionic Bonds and Ionic Compounds

2. Formation of Ionic Compounds
Ionic Compounds—compounds composed of anions and cations.
Although they are composed of ions, ionic compounds are electrically neutral.
One atom loses electron(s) and achieves a stable noble gas electron configuration; the other atom gains electron(s) and achieves a stable noble gas electron configuration.

3. With ionic compounds, there are no single discrete units, only a continuous array of ions.
Chemical formula—shows the kinds and numbers of atoms in the smallest representative unit of a substance.
The chemical formula of ionic compounds refers to a ratio known as a formula unit (the lowest whole-number ratio of ions).

4. Ionic charges are not shown when writing the formula unit of an ionic compound.

5. Properties of Ionic Compounds
Most are crystalline solids at room temperature.
The component ions are arranged in repeating three-dimensional patterns.
Large attractive forces between ions result in a very stable structure, so ionic compounds generally have high melting points.

6. Coordination number of an ion—the number of ions of opposite charge that surround the ion in a crystal.
Ionic compounds can conduct an electric current when melted or dissolved in water.