This bond arises when one atom completely transfers valence electrons to another atom. Valence electrons are the outermost electrons involved in any standard chemical reaction. The bond formation is driven by a large difference in atomic electronegativity.
Electronegativity measures how strongly an atom pulls electrons toward its own nucleus. The difference on the Pauling scale generally exceeds 1.7 for ionic bonds. Metals have low ionization energies and easily lose their outermost valence electrons.
They form positively charged cations during this simple electron transfer process. Nonmetals have high electron affinities and gladly accept these newly freed electrons. This electron transfer quickly turns the nonmetal atoms into negatively charged anions.
The oppositely charged ions are then drawn together by strong electrostatic forces. They organize themselves into a continuous and highly ordered three-dimensional crystal lattice. A crystal lattice is a repeating geometric pattern of atoms or ions.
This rigid structure maximizes attractive forces and minimizes internal ionic repulsions. The chemical strength of this orderly arrangement is known as the lattice energy. Lattice energy is the primary driving force for creating stable ionic compounds.
It gives these solid materials their characteristic high melting and boiling points. In a solid state, the rigid lattice completely prevents any free ion movement. This restriction makes solid ionic compounds function as excellent electrical insulators.
However, these compounds become highly conductive when melted or dissolved in liquid water. The liquid state completely frees the trapped ions to move and carry electricity.