Here's the problem in a nutshell:
Elements 1 through 20 are theoretically supposed to build molecular structure using just those spherical and dumbell shaped thingies: the s- and p-orbitals. Theoretically speaking, no more than eight valence electrons should ever surround those atoms. This is the octet rule, and also explains why no more than four atoms ever surround those elements. The octet rule is supposed to apply to phosphorus, sulfur, and chlorine. And yet...
Fact: PF5 and SF6 exist, in apparent violation the octet rule. PF5 has ten valence electrons (2 in each bond) and SF6 has twelve. Also, some pretty common species like phosphate, sulfate, and perchlorate, appear to violate the octet rule. Those are pretty serious charges. Good men may have even killed themselves over the very issue. Link
Look, intelligent people disagree on many topics. As an aside, the ancient name for sulfuric acid was vitriol, which nowadays mostly means nasty rhetoric. But consider the word's origins. According to the OED, vitriol, H2SO4, was so-named because of the glassy-like appearance of concentrated sulfuric acid. I love how so many words are, in the end, just metaphors. Vitriol is an ancient substance, and came to us by way of alchemy. By the way, we spell it "sulfuric" and the Brits spell it "sulphuric."
You should have seen what I was going to post on this topic. Something about D-orbitals.