VSEPR Theory
            „ In any molecule or ion there are 
               regions of high electron density:
                „ Bonds (shared electron pairs)
                „ Lone pairs (unshared electrons)
            „ Due to electron-electron repulsion, 
               these regions are arranged as far 
               apart as possible
            „ Such arrangement results in the 
               minimum energy for the system
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           Five Basic Geometries
          Linear             Trigonal
                                          Tetrahedral
                                      Octahedral
      Trigonal bipyramidal
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             CH , NH , and H O
                   4         3             2
           ƒ These molecules have the same electronic 
            geometry but different molecular geometry
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              Electronic Geometry and 
              Molecular Geometry
          ƒ Electronic  geometry
          ƒ Electronic  geometry
             ƒ Distribution of regions of high electron density 
               around the central atom
          ƒ Molecular geometry
          ƒ Molecular geometry
             ƒ Arrangement of atoms around the central atom
          ƒ If a molecule does not have lone electron 
            pairs, both geometries are the same
          ƒ If lone pairs are present, molecular and 
            electronic geometries are different
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