Ionic compound
From Wikipedia, the free encyclopedia
In chemistry, an ionic compound is a chemical compound in which ions are held together in a lattice structure by ionic bonds. The positively charged ion is usually a metal ion and the negatively charged ion is non-metallic element or molucule.
Ions can be single atoms, as in common table salt sodium chloride, or more complex groups such as calcium carbonate. But to be considered ions, they must carry a positive or negative charge.
Thus, in an ionic bond, one 'bonder' must have a positive charge and the other a negative one. By sticking to each other, they resolve, or partially resolve, their separate charge imbalances. Positive to positive and negative to negative ionic bonds do not occur. (For a real world analogy, experiment with a pair of bar magnets.)
Ionic compounds have strong bonds between particles and thus generally have high melting and boiling points. They have good electrical conductivity when molten or in aqueous solution. While ionic inorganic compounds are solids at room temperature and will usually form crystals, organic ionic liquids are increasingly of interest.
Ionic compounds also dissolve in polarised liquids, of which water is an example, while they do not dissolve in organic liquids, such as Petrol. This is the opposite of covalent compounds.
When an ionic compound is named, the cation is named first and then the anion. When an elemental anion is named, the suffix, -ide, is added to the name of the element. There are two common types of cations: Type I and Type II. Type I cations have only one charge and their name is simply listed when the compound is named. Type II cations have more than one charge and when the ionic compound is named, a Roman numeral is used to denote the charge of the cation. In addition, there are common polyatomic anions which do not have suffixes in their name such as hypochlorite (ClO–).
