* Sodium (Na) has one valence electron in its outermost shell. It wants to lose this electron to achieve a stable octet (8 electrons) in its outermost shell. When it loses this electron, it becomes a positively charged ion called a sodium cation (Na+).

* Chlorine (Cl) has seven valence electrons in its outermost shell. It wants to gain one electron to achieve a stable octet. When it gains an electron, it becomes a negatively charged ion called a chloride anion (Cl-).

In summary:

* Sodium atom (Na) --> Sodium cation (Na+)

* Chlorine atom (Cl) --> Chloride anion (Cl-)