Here's how to determine the empirical formula of the ionic compound formed by sodium (Na) and fluorine (F):

* Identify the charges:

* Sodium (Na) is in group 1 of the periodic table and forms a +1 ion (Na⁺).

* Fluorine (F) is in group 17 and forms a -1 ion (F⁻).

* Balance the charges: To form a neutral compound, the positive and negative charges must balance. Since the charges are already equal and opposite, we need one sodium ion (Na⁺) and one fluoride ion (F⁻).

* Write the formula: The empirical formula is simply the combination of the ions: NaF.