In which species does the central atom have one or more lone pairs of valence electrons?

S is the primary element in the SO2 molecule, whereas O is its neighbour.
Bond pairings = other elements in the formula besides the primary element + 2
Number of lone pairs = $1/2 \times$ (No. of the central atom's valence electrons - Total No. of bonds present between the central element and the surrounding elements) =$1/2 \times$ (6 - 4) = 1