ionic+bonding

Ionic compounds are composed of metallic and nonmetallic ions of opposite charges held together through electrostatic forces (ionic bonds).



The difference between ionic and covalent compounds is twofold:
 * ionic compounds contain metals - covalent compounds do not;
 * ionic compounds do not share electrons amongst one another.

There are three classes of ions which dictate the manner in which the compounds are named.

Type I Cations are elements that have only one oxidation state (ionic charge). These include all the elements in the alkali metals and alkaline earths (+1 and +2 charges, respectively). There are a few more scattered across the p and d block, such as silver, zinc, and aluminum.

Type II Cations are elements that have more than one possible oxidation state. These elements are mainly found in the d block, and some are in the p block. For example, iron can have a +2 charge (called iron (II) ) or a +3 charge (called iron (III) ). Roman numerals are used to distinguish the two or more different oxidation states of the Type II cations.

Anions are the negatively charged ions of nonmetals.

Polyatomic ions are ions made up of more than one atom (as inferred by the name) and are treated as one large ion instead of a group of charged atoms.

The ionic bond is very powerful, and will bind cations and anions together so tightly that they form crystalline solids.