It is already more Electronegative.
Those are all Electronegative atoms.
Fluorine itself is highly Electronegative, meaning it really really likes to attract electrons to itself.
As the most Electronegative element, it is extremely reactive,
as it reacts with almost all other elements, except for helium.
Since it's the second most Electronegative element, oxygen in a compound always has
an oxidation number of -2(with only a few exceptions).
As the most Electronegative element, it is extremely reactive,
as it reacts with almost all other elements, except for helium and neon.
Fluorine is the most Electronegative element(i.e. it exerts the strongest pull on electrons),
so in a compound it always has an oxidation number of -1.
Water is a polar molecule because its oxygen is strongly Electronegative and, as such, pulls the electron pair towards itself(away from the two hydrogen atoms),
thus acquiring a slightly negative charge.