Hybridization and Resonance

Hybridization is the idea that atomic orbitals fuse to form newly hybridized orbitals, which in turn, influences molecular geometry and bonding properties. Hybridization is also an expansion of the valence bond theory. It is found by counting the number of electron domains around the central atom, which determines the number of hybrid orbitals are required. It uses the sub-levels: s, p, d, f. S has one orbital, p has three, d has five, and f has seven.

Hybridization looks similar to locations of electrons, but the amount of space in each sub-level is counting the number of orbitals, not the number of electrons. More information can be found here.

The resonance of a molecule or ion were the bond aren't all the same (all either single, double, or triple) and the other bonded atoms can take the bond that is being moved, were the double or triples bonds are can switch. Basically the Lewis dot structure of a molecule or ion can be drawn in multiple ways.

Carbon trioxide had resonance

The structure with the mean resonance is called the resonance hybrid. This is the most accurate form of the molecule or ion. It equalizes bond length and strength. More infomation if resonance can be found here.