How does the electron-pair model explain the formation of sodium chloride?

In the context of Gilbert N. Lewis’s research, it is important to clarify that while he is famous for the electron-pair model of covalent bonding, he also proposed a distinct mechanism for ionic compounds like sodium chloride.12

According to the Lewis model, the formation of sodium chloride does not involve the sharing of an electron pair, but rather the complete transfer of an electron. The process is explained as follows:23

• Electron Transfer: Sodium has one electron in its valence shell. By donating this electron to chlorine, which requires one more electron to complete its valence shell, both atoms achieve the stable electronic configuration characteristic of their nearest noble gas.24
• Ion Formation: Once the transfer occurs, the sodium atom becomes a positively charged cation (Na⁺), and the chlorine atom becomes a negatively charged anion (Cl⁻).24
• Electrostatic Attraction: The resulting ionic bond is maintained by the strong electrostatic attraction between these oppositely charged ions, which locks them together into a stable crystal structure.34

This transfer process is guided by the octet rule, which states that atoms tend to gain, lose, or share electrons to acquire a full outer shell of eight electrons.2