dr. s. m. condren chapter 10 molecular geometry and chemical bonding theory
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Dr. S. M. Condren
Chapter 10
Molecular Geometry and
Chemical Bonding Theory
Dr. S. M. Condren
What is the “shape” of the molecule?
• How are valence electrons in a molecule distributed among the orbitals?
• What are the shapes of these orbitals?
• What order are they occupied?
Dr. S. M. Condren
Molecular GeometryVSEPR Theory
Valence Shell Electron Pair Repulsion Theory
• draw Lewis electron dot structure
• count the number of bonding electron pairs about central atom (double and triple bonds count as one pair for shape prediction)
• count the number of lone pairs of electrons
• match electron pair information to shapes
Dr. S. M. Condren
Dr. S. M. Condren
Dr. S. M. Condren
Dr. S. M. Condren
Dr. S. M. Condren
Shape: PCl3
Lewis Electron Dot Structure .. .. ..:Cl P : Cl: .. .. .. :Cl: ..
3 bond pairs1 lone pair => AB3E
trigonal pyramidal shape
Dr. S. M. Condren
Shape: IF5
Lewis Electron Dot Structure
.. ..
: F : : F : .. .. .. : I : F : .. .. .. : F : :F :
.. ..
5 bonds pairs1 lone pair => AB5E
Square pyramidal shaped
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Shape: IF4-1
Lewis Electron Dot Structure
.. .. -1
: F : : F : .. .. .. : I : F : .. .. .. : F :
..
4 bond pairs2 lone pairs => AB4E2
square planar shape
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Shape: SO3
Lewis Electron Dot Structure
.. : O : S : : O : .. .. .. : O :
..
3 bond pairs
0 lone pairs => AB3
trigonal planar shape
Dr. S. M. Condren
What would be expected to be the shape of chloroform, CHCl3?
“see-saw”
square planar
tetrahedral
Dr. S. M. Condren
Dr. S. M. Condren
http://www.colby.edu/chemistry/OChem/DEMOS/Orbitals.html
Hybrid Orbitals
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Dr. S. M. Condren
Dr. S. M. Condren
What would be the name of the hybrid orbitals created by joining 1s type, 3 p type and 2 d type orbitals?
spd
sp3d2
s3p2d
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Bonding in Water
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Hydrogen Bonds
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Water, H2O, and methane, CH4, have very similar molar masses yet the boiling point for water is approximately 200oC higher than that for methane. The higher boiling point is due to:
hydrogen bonding in water
polarity of water molecules
both of the above
none of the above
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Carbon monoxide, CO and carbon dioxide, CO2, are linear molecules. Which one is the polar molecule:
CO
CO2
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Sigma Bond Bond with the greatest electron density on a line connecting the atomic nuclei
s-s type p-p type s-p type
s-sp3 type s-sp2 type s-sp type
p-sp3 type p-sp2 type p-sp type
sp3 - sp3 type sp2-sp2 type sp - sp type
etc., including all combinations of s, p, d, and hybrid orbitals
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Dr. S. M. Condren
Pi Bond
Bond with the greatest electron density above and below a line connecting the atomic nuclei
p-p type
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Bonding in Ethylene
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Bonding in Acetylene
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Molecular Orbital Diagram
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Molecular Orbital Diagram
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Molecular Orbital Diagram
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Molecular Orbital DiagramN NN2