Final answer:
In the formation of NaCl, the valence electron of sodium is transferred to chlorine, forming oppositely charged ions and creating an ionic bond.
Step-by-step explanation:
In the formation of NaCl, sodium (Na) donates a single electron to chlorine (Cl) atoms. This generates Na+ and Cl- ions. The oppositely charged ions then come together forming an ionic bond, which is an electrostatic interaction of opposite charges that holds the Na+ and Cl- ions together in crystal salt.
For example, in the case of NaCl, the difference in electronegativity between Na (0.93) and Cl (3.16) causes the chlorine atom to attract the valence electron of the sodium atom very strongly. Sodium loses an electron and forms an Na+ ion, while chlorine gains an electron and forms a Cl- ion.
Overall, the valence electrons of sodium and chlorine interact by one electron from sodium being transferred to chlorine, resulting in the formation of oppositely charged ions that create the ionic bond in NaCl.