When an atom of sodium (Na) combines with an atom of fluorine (F), the resulting compound is sodium fluoride (NaF). Sodium fluoride is an ionic compound, meaning it is composed of positively charged ions (cations) and negatively charged ions (anions). In this case, the sodium atom loses one electron to the fluorine atom, resulting in a sodium cation (Na+) and a fluoride anion (F-). These ions then combine to form sodium fluoride.