`OF_(2)` is called oxygen difluoride, whereas `Cl _(2)O` is called dichlorine monoxide. Why ?

Explanation

Electronegativity of O in `OF_(2)` is less than F. Therefore, there will be positive charge on oxygen and negative charge on fluorine. Whereas in Cl and O, electronegativity of Cl is less than that of O therefore there will be positive charge on Cl and negative charge on O. Positive charge is written first followed by negative charge.