chemical bonding and molecular structure chapter 12 sec 12.8 - 12.10
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Chemical Bondingand Molecular Structure
Chapter 12Sec 12.8 - 12.10
Goals:
1. To use Lewis Structures as a way to predict the geometry of Molecules
2. Determine if molecules are polar or nonpolar
VSEPR Model
• Valence Shell Electron Pair Repulsion Model
• Bonds (pairs of electrons) attempt to move as far away as possible from one another in a molecule
This explains the Geometry of H2O
Water is a “bent” molecule, because
of the lone pairs around the central
Oxygen atom
Various Geometry of Molecules
See Examples on Next Slides
(Hand-Out)
Polar or Non-polar Molecule?
A molecule may have polar covalent
bonds and not be polar overall?????????
Geometry must also be considered
Ammonia (NH3) is polar
1. The bonds between hydrogen and nitrogen are polar covalent (∆EN = .87)
2. Pyramidal geometry of molecule points charges toward N
Carbon Dioxide is Non-polar
Even though the bonds between carbon and oxygen are polar covalent (∆EN = 1.0), the pull of electrons is in equal and opposite directions because CO2 is linear
Water is Wacky!
Water has some strange properties due to its structure
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