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SCH 4U Hybridization of Atomic Orbitals ppt

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					Hybridization of
Atomic Orbitals


  Some Material Copyright PGCC CHM 101 Sinex
Some Graphics from Nelson Chemistry 12 Textbook
Atomic Orbitals Don’t Work?
To explain molecular geometry:
• In methane, CH4 , the shape is
  tetrahedral.
• The valence electrons of carbon should
  be two in s, and two in p.
• The p orbitals would have to be at right
  angles.
• The atomic orbitals change when making
  a molecule
      Valence Bond Theory
• Atomic orbitals overlap when a bond is
  formed between atoms
• A new set of orbitals is formed
• Each orbital contains a pair of electrons
• These are called hybrid orbitals
• How do they look? See p234 Table 1
           Hybridization
• p234 Table 1
Ex: sp3 hybridization
        sp3 Hybridization
• The s and p orbitals blend and end up
  with the tetrahedral geometry.
• one s orbital combines with three p
  orbitals.
• sp3 hybridization has tetrahedral
  geometry.
         In Terms of Energy

               2p
               Hybridization   sp3
Energy




          2s
            Notation?
                 sp3

• One s orbital and three p orbitals
• Each orbital holds 2 electrons
Illustrating Hybridization
    Animation of hybridization
          hybridization
     Visualization of orbitals
         hybrid orbitals
   Double and Triple Bonds
Ex: C2H4
• Double bond acts as one pair.
• Geometry - trigonal planar
• Have to end up with three blended
  orbitals.
• Use one s and two p orbitals to make sp2
  orbitals.
• Leaves one p orbital perpendicular.
    Where is the P orbital?
• Perpendicular
• The overlap of orbitals (end-to-end)
  makes a sigma bond ( bond)
hybrid orbitals – sp, sp2, or sp3
formation of  bond
               bond




remaining p orbitals form sp or sp2
 bond hinders rotation   Planar molecule (each carbon
about the carbon-to-      is trigonal planar) with  cloud
carbon bond               above and below the plane




              The overlap of orbitals
                  (side-to-side)
                     makes a
                 pi bond ( bond)
       sp Hybridization

• End up with two lobes 180º apart.
• p orbitals are at right angles
• Makes room for two  bonds and
  two  bonds.
• A triple bond or two double bonds.
          Bond Formation From
             Hybridization
  • Single bond           end-to-end
       - sigma bond
  • Double bond                  side-to-side
       – sigma bond + pi bond
  • Triple bond
       – sigma bond + pi bond + pi bond

How are the two pi bonds in the triple bond oriented?
   How about the electron density
        around a C-C bond?

Polar or
Non-polar

                             C2H4
               C2H6                       C 2H 2


                                                         H+
                                                      attack?



            single bond   double bond   triple bond
Summary

				
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posted:8/19/2012
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