Molecular Geometry

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Molecular Geometry

• NCSCOS Essential Standard Chm 1.2.3

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I. VSEPR Theory

• Valance Shell Electron Pair Repulsion
• Gives molecules their shape
• Pairs of electron repel to be as far apart as
  possible

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II. Shapes (Geometries)

• Linear
• A2 ex F2
• AB ex HCl
• AB2 (with a double bond) ex CO2

carbon dioxide
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• Trigonal Planar
• AB3
• no unshared pairs of electrons
• Usually occurs w/ elements that do not fulfill
  the octet rule (ex B)
• BH3

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• Tetrahedral
• AB4
• No unshared pairs of electrons
• Ex CH4

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• Bent or Angular
• AB2E2
• 2 unshared pairs of electrons
• Ex H2O OH2

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• Trigonal Pyramidal
• AB3E
• 1 pair of unshared electrons
• Ex NH3

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III. Molecule Polarity

• Polar Molecules opposite ends of the molecule
  contain opposite partial charges.
• Electrons are not distributed evenly across the
  molecule
• Ex H2O
• All molecules that have E, and some linear.

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• Nonpolar Molecules no opposite charges
• Electrons are evenly distributed across the
  entire molecule
• All molecules that do not have an E diatomic
  molecules.
• Ex CH4
• Ex Cl2