Final answer:
Sodium (Na) donates its valence electron to chlorine (Cl), forming Na+ and Cl- ions that are held together by an ionic bond in sodium chloride (NaCl). This process involves electron transfer that satisfies the octet rule and results in a stable compound.
Step-by-step explanation:
The valence electron of sodium (Na) reacts with the valence electrons of chlorine (Cl) to form an ionic bond, resulting in the formation of sodium chloride (NaCl). Sodium has one valence electron in its outermost shell, which it readily donates due to its low ionization potential, becoming the Na+ ion. Chlorine, with seven valence electrons, has a high electronegativity and gains this electron, thus forming the Cl- ion. This transfer of an electron satisfies the octet rule, creating a stable configuration similar to that of noble gases for both ions. The Na+ and Cl- ions then attract each other due to opposite charges, leading to an ionic bond that holds the compound together.