Bonding #7 -- Resonance Stuctures and Delocalized Bonding of Electrons in Covalent Molecules

     Read the following text and illustrations to help understand what resonance Lewis Structures actually mean in terms of real molecules.  They involve delocalized bonding, or electrons that are not just shared between two atoms like in a normal ("localized") covalent bond, BUT instead are shared over three or more atoms/across the whole molecule.

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     Look at the following illustration to help understand delocalized pi bonding in molecules that have resonance structures.  Picutre (a) shows a 2-D molecular skeleton.  Picutre (b) shows the skeleton with unhybridized  p orbitals perpendicular to plane of molecule.  Picutre (c) shows  "merged" p orbitals above/below the plane of the molecule, with  delocalized electrons shared over the whole molecular instead of just between two atoms.  And picture (d) showing the electron cloud (made up of the regular covalently bonded electrons in their hybrid orbitals, as well as the delocalized electrons) surrounding whole molecule, with electron density shown by color.