Chemical bond NaF.

By their nature, chemical bonds are divided: covalent polar and non-polar, metallic, hydrogen.
In our case, there is a substance – sodium fluoride. It has an ionic (extreme case of a covalent polar) bond, since it consists of two elements of different electronegativity. If the difference in electronegativity is greater than 1.9, then this is an ionic bond. In our case, the electronegativity of sodium is 0.9, that of fluorine is 4.0, that is, the difference is 4.0-0.9 = 3.1, this is an ionic bond.