How are ionic substances formed?

Ionic bonds are made when one of the two atoms that are reacting has excess electrons and transfer the electrons to the atom that is deficient in electrons.

An ionic compound is formed by the complete transfer of electrons from a metal to a nonmetal and the resulting ions have achieved an octet. The protons do not change.

Explanation:

Ionic bonding is the complete transfer of valence electron (s) between atoms. It is a type of chemical bond that generates two oppositely charged ions. In ionic bonds, the metal loses electrons to become a positively charged cation, whereas the nonmetal accepts those electrons to become a negatively charged anion.