Question

By formula method the hybridisation of SO3, but it comes under SO2. why is it so​

Answer 1

We start by noting that, in SO2SO2 , sulfur has six valence electrons.

SO2SO2 can be depicted in either of two ways: an octet-based structure in which sulfur has a +2 formal charge, and an extended-octet structure in which sulfur has two double bonds. In both structures, sulfur has two oxygen ligands and a lone pair:

In the left-hand structure, sulfur uses four electrons to make the two double bonds, leaving two for a lone pair.

In the right-hand structure, sulfur uses two electrons to make the two single bonds, and loses two for the formal charge, again leaving two for a lone pair.

Qualitatively, hybridization can be estimated by a compound’s VSEPR electron geometry. Sulfur in SO2SO2 has three electron groups, so its electron geometry is trigonal planar. The atom geometry is “bent,” of course.

Trigonal planar electron geometries are sp2sp2 hybridized. End of story.

Answer 2

The SO2 hybridizationis sp2 for the central sulfur atom. It's also sp2 for each of the oxygen atoms as well. A description of the hybridization SO3 including π and sigma bond. The SO3 hybridization is sp for the central carbon atom.