As far as I know, when writing Lewis structures for molecules, we need to consider the octet rule and the valence electrons each atom has.
But, if we take for example, the molecule $ Cl O_2^- $ , we have the following Lewis structure: (as it appears here ) O - Cl - O with 6 valence electrons surrounding each oxygen atom, and 4 valence electrons surrounding the chlorine atom.
My problem is: The oxygen atom has 6 valence electrons. By forming a chemical bond with the chlorine atom, it shares one electron, which leaves it with a total of 5 non-bonded electrons. So, how can it be that in the Lewis structure of this molecule, it has 6 non-bonded electrons and one shared electron? (or a total of 7 electrons! )