Here's why:
* Sodium (Na): Sodium has one valence electron in its outermost shell. By losing this electron, it becomes a positively charged sodium ion (Na+) with a full outer shell of 2 electrons, achieving the same electron configuration as neon (Ne).
* Chlorine (Cl): Chlorine has seven valence electrons. It gains one electron to complete its outermost shell, becoming a negatively charged chloride ion (Cl-) with a full outer shell of 8 electrons, achieving the same electron configuration as argon (Ar).
Therefore, both ions achieve the stable electron configuration of a noble gas, making the ionic bond favorable. This is a common driving force behind ionic bonding, as atoms strive to attain the stable electron configurations of noble gases.
