Question

I really can't understand why a molecule can have more or less than 4 electron pairs? for example, how can sulfur hexaflouride have 6 single bonds?? then wouldn't it mean that sulfur can have 12 electrons in it's valence shell? and I am also confused about how there can be molecules with 5 or 6 high electron density regions, can someone pleeeeaaaase explain to me I thought that every atom (except hydrogen) must have 8 valence electrons when forming molecules.

Answer 1

Im really confused by that as well, its called hypervalency and theories are split amongst scientists

Answer 2

As sbhb91 wrote, the phenomena is called hypervalency and that's why sulfur hexafluoride is called a complex molecule. Most scientists would explain that with hybridization (like in carbon atoms) but in more complex ways so that sulfur can form six "hybrid molecular orbitals" (I don't know if that's is the correct name)

Answer 3

The typical "octet" is a result of the hybridization of the s and p orbitals. The s can hold 2 electrons, the p can hold 6. This gives 8 electrons for the octet. Elements that violate the octet (and many do) are able to do this by hybridizing d orbitals as well to produce more than 4 hybrid orbitals. The VSEPR theory that you typically learn in highschool/undergrad college only teaches you up to sp3 hybridization. This is because, lets face it, after that sh** gets crazy.

Answer 4

brendanchandler88: I completely agree, I currently have to learn hybridization with d orbitals and it is insane at some points where I have to predict the geometrical configuration and type of hybridization in metallic and xenon complexes.