Oxygen difluoride, or OF2, is a polar molecule. If its Lewis dot structure is analyzed, it is observed that the two fluorine molecules are attached to a central oxygen molecule, along with two pairs of unpaired electrons. Therefore, fluorine is slightly more negative while the oxygen atom is more positive.
Taking the Lewis dot structure of oxygen flouride and applying VSEPR geometries to the molecule, it is found that the two pairs of unpaired electrons push the fluorine atoms, creating a "bent" line with the oxygen. This bend forces the charges of the fluorine atoms not to cancel each other out. Fluorine is a more electronegative element, so it pulls electrons closer than oxygen atoms can, leaving more electrons near the fluorine atoms and creating a polar molecule.