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How does an ionic bond form between sodium and chlorine?

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Bohr model diagram of a hydrogen atom showing a green nucleus labeled H, a single electron orbit, and text with atomic mass 1.008 and electron configuration 1. — atom The Bohr model describes the structure of atoms, in this case hydrogen.

An ionic bond between sodium and chlorine forms through the transfer of an electron from the sodium atom to the chlorine atom, allowing both to achieve stable outer electron configurations.12

Sodium, an alkali metal, has one valence electron in its outermost orbital. It readily loses this electron to become a positively charged cation, ${Na}^{+}$ , thereby exposing a stable core. Conversely, chlorine is highly electronegative and gains that electron to complete its valence shell, forming a negatively charged anion, ${Cl}^{-}$ .231

The resulting ionic bond is the electrostatic attraction between these oppositely charged ions. While energy is initially required to ionize the atoms, the formation of a crystalline array releases a large amount of lattice energy as cations and anions pack together. This strong, nondirectional attraction between the ions is what holds the sodium chloride structure together.241