GAS PHASE, \[S{{O}_{3}}\] molecule is triangular PLANAR having \[s{{p}^{2}}\]-hybridisation of the S-atom. There are three SIGMA bonds formed by \[s{{p}^{2}}\]-P overlap and three pi-bonds are by one \[p\pi -p\pi \]overlap and two \[p\pi -d\pi \]overlap.