Ionic bonds are most likely to occur when one atom has a small number of valence electrons (typically 1, 2, or 3) and another atom has a relatively high number of valence electrons (typically 5, 6, or 7).
In general:
- Atoms with 1, 2, or 3 valence electrons (like alkali and alkaline earth metals) tend to lose these electrons and form positive ions (cations).
- Atoms with 5, 6, or 7 valence electrons (like halogens and chalcogens) tend to gain electrons to achieve a full valence shell and form negative ions (anions).
This transfer of electrons from the metal to the non-metal results in the formation of ionic bonds. The resulting electrostatic attraction between the oppositely charged ions creates the ionic compound.