Ionic bonds are formed through electrical attractions between oppositely charged ions, specifically cations and anions. Unlike covalent bonds, which involve the sharing of electrons, ionic bonds are characterized by a complete transfer of electrons from one atom to another. This transfer allows both atoms to achieve full valence shells, which is crucial for their stability.

For example, in the formation of sodium chloride (NaCl), sodium (Na) has one electron in its outermost shell, while chlorine (Cl) is highly electronegative and has a strong tendency to attract electrons. The significant difference in electronegativity between sodium and chlorine results in chlorine effectively "stealing" the electron from sodium. As a result, sodium loses its single valence electron, leading to a full valence shell beneath it, while chlorine gains that electron, completing its own valence shell.

After this electron transfer, sodium becomes a positively charged ion (Na⁺), and chlorine becomes a negatively charged ion (Cl^-). The attraction between these oppositely charged ions forms the ionic bond. This interaction not only fills the valence shells of both atoms but also creates the ionic compound sodium chloride, which is commonly known as table salt.

In summary, ionic bonds are essential for the formation of stable compounds like NaCl, demonstrating how the transfer of electrons leads to the creation of charged ions that attract each other, resulting in a stable ionic structure.