How many lone pair in SO3
The short answer to your question is eight. Here is the long answer: SO3 has a total of 24 valence electrons. The central S is bonded to each of the O atoms. In the dot structure, one of the O atoms is double bonded to the S while the others have a single bond. This gives S its octet, using 8 of the valence electrons. The remaining 16 electrons exist as lone pairs. The two single bonded oxygens each have three lone pairs of electrons to obtain their octet. The double bonded oxygen has two lone pairs to obtain its octet. Since the double bond oxygen could be any of the three oxygens, the molecule is actually a combination of all three structures (the resonance structure).
