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VSEPR and Molecular Geometries. VSEPR Theory. V alence S hell E lectron P air R epulsion Theory Based on the idea that like charges . . . repel each other (according to Coulomb’s Law). VSEPR Theory. V alence S hell E lectron P air R epulsion Theory VSEPR says:
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VSEPR Theory • Valence Shell Electron Pair Repulsion Theory • Based on the idea that like charges . . . repel each other (according to Coulomb’s Law)
VSEPR Theory • Valence Shell Electron Pair Repulsion Theory • VSEPR says: A molecule adopts the geometry that minimizes the repulsive force among a given number of electron groups.
VSEPR Theory • The arrangement of electron groups that minimizes repulsion is called the electron-pair geometry. • “electron groups” bonding groups (single/double/triple bond) unshared pairs
VSEPR Theory • The arrangement of electron groups that minimizes repulsion is called the electron-pair geometry. • The resulting arrangement of atoms (in terms of bond lengths and bond angles) is called the molecular geometry.
VSEPR Theory • There are five electron-pair geometries: • Linear • Trigonal planar • Tetrahedral • Trigonalbipyramidal • Octahedral • There are additional molecular geometries (the names of which you will learn in lab).
3-d Lewis Structures You will need to be able to show three-dimensionality in drawings when asked. SF6 Cannot draw bonds straight out or straight back
3-d Lewis Structures AsF5 With trigonalbipyramidal electron-pair geometry, keep the axial bonds axial and the equatorial bonds equatorial.