# How many valence electrons are possessed by an oxygen atom?

...........which means its ions MIGHT have a $- 2$ electronic charge.
The oxygen ATOM has $Z = 8$, i.e. 8 protonic charges. The neutral atom thus must have 8 electronic charges, 2 of which are inner core, and the remaining 6 are valence electrons. It tends to form ions with 8 valence electrons, i.e. ${O}^{2 -}$, tho' other ions are possible.
In elemental oxygen, the stuff we are breathing now, we conceive a structure of :stackrel(ddot)O=stackrel(ddot)O:, and of course this is neutral, and the 6 valence electrons are apparent; the 4 electrons which comprise the double bond are conceived to be shared by the bound atoms.