http://www.colby.edu/chemistry/OChem/demoindex.html (http://www.colby.edu/chemistry/OChem/demoindex.html)
OK, SO2: S has 6 valence e- and same with O. So wouldn't it make sense for S to form a double bond with EACH O atom? (As in O=S=O) Yet we know that SO2 is O=S-O [leaving the S with 3 unpaired valence shell electrons?]; well, acutally it looks a bit different because of delocalization. So, obviously I have a poor grasp of this very simple octet rule. If one of my fellow bees, so wise in the ways of chemistry could help this little dolt, it woiuld be appreciated.
Your only thinking 1/2 way through the problem, sure it seems to make sense to have the 4 bonds, but now count how many electrons that takes up, and how many you have left? now distribute the ones that you have left (unbonded) and keep the octet rule from being broken... well guess what, there's nowhere to put those extra 10 electrons, now take one of the bonds away to leave O=S-O and now distribute the remaining 12 electrons that aren't forming bonds, and hey it's now filling the desire of the elements to reach noble gases (full shells) SO2 is neither O=S-O or O=S=O it's really "O=S-O <-> O-S=O"
AFAIK
Regards
http://www.webelements.com/webelements/elements/text/S/econ.html (http://www.webelements.com/webelements/elements/text/S/econ.html)
. In that state you can see sulphur has only 2 unpaired electrons.