When one molecule of sodium (Na) combines with one atom of chlorine (Cl), they form one molecule of sodium chloride (NaCl), commonly known as table salt.

This is a classic example of an ionic bond, where the sodium atom loses an electron to become a positively charged ion (Na+), and the chlorine atom gains an electron to become a negatively charged ion (Cl-). The opposite charges attract each other, forming a strong ionic bond.