Ionic bonds are formed between cations and anions in crystalline solids. The positive ions are surrounded by a lattice of negative ions. The negative ions are likewise surrounded by a lattice of positive ions. The multiple oppositely charges ions attract one another. The forces of attraction are multiplied by the number of interacting particles. Ionic substances typically are solids at room temperature. The solid is made up of a regular pattern of positive and negative ions. The ions are held in place by electrostatic forces.

Look at the illustration of the sodium chloride crystal. There are two intertwined lattices. The white balls represent sodium ions and the green ones represent chloride ions. In sodium chloride an Na¹⁺ ion has six chloride ions nearby. This multiplies the forces of attraction. The chloride ions are also surrounded. But they have six sodium ions nearby.

Ionic bonding theory:

A nonmetal and a metal will typically combine to form a binary ionic compound. (a binary compound is made from only two elements) This is a very reliable rule of thumb for predicting the formation of ionic bonding. You can generally say that metals form cations and nonmetals form anions. These oppositely charged particles are electrostatically attracted. Typically the energy of attraction between only one anion and one cation is not strong enough to provide the energy needed to strip off electrons from the metal. This is why ionic substances are not simple combinations like pairs of ions. The required energy can be provided only when many ion pairs interact.