It turns out that there is indeed a substance that has stronger oxidation power than fluorine! Switch the hydrogen atoms of water with fluorine atoms, and you get oxygen difluoride, a compound with slightly stronger oxidizing power compared to elemental flouride. Fluorine, F2, has a standard redox potential of 3. read more
Therefore it cannot show variable oxidation state like other members of the group and shows only minus one as oxidation state (-I). Fluorine is strongest oxidizing agent. read more