The monoatomic ionic forms of both oxygen and sulfur have a 2- charge (O2- and S2-). Both oxygen and sulfur are representative elements. Bases on this information, predict which groups oxygen and sulfur belon to.
The negative 2 charge means that these two representative elements have gained two additional electrons to obtain 8 electrons in their valence shells, consequently, the neutral atoms of both these elements have 6 electrons in their valence shells. This place both these elements in Group VIA.