What is the hybridization of the central atom of each of the following molecules? a.) h2o b.) pbr5 c.) cocl2? you so much!

 The notion of hybrid orbitals was "invented" by Linus Pauling in 1931 to explain the observed geometry of mostly organic molecules. Today, we find that hybrid orbitals are pretty much confined to the central atoms found in the second period of the periodic table. Periods 3 and up not so much. 

(a) H2O O is the central atom, tetrahedral, sp3 hybridization 
(b) PBr5 P is the central atom, maybe sp2 for the three equatorial bonds * 
(c) COCl2.. C is the central atom, trigonal planar, sp2 hybridization 

So the main goal for the elements is stability which is a complete/full valence shell and typically the magic number for a stable element is 8 valence electron but not always. so elements to the left of the periodic table tend to be way less stable then those on the right, so the elements on the left are much more reactive.