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Molecular Geometry. Using VSEPR. VSEPR. Valence Shell Electron Pair Repulsion OK smart guy/gal what’s it mean?. Meaning. The valence electrons pairs repel each other. Determines the geometry or shape of the molecule. Electron pairs will be as far away from each other as possible….
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Molecular Geometry Using VSEPR
VSEPR • Valence • Shell • Electron • Pair • Repulsion • OK smart guy/gal what’s it mean?
Meaning • The valence electrons pairs repel each other. • Determines the geometry or shape of the molecule. • Electron pairs will be as far away from each other as possible…
Steps for determining molecular shape • Determine the number of valence e- groups around the central atom. • Determine the number of groups that are bonding… • Chose the geometry that allows the greatest distance between electron pairs.
Lewis Diagram CH4 • How many valence e- pairs around central atom? • How many bonding pairs? • How far away from each other can they get????
Tetrahedral geometry • Ex. CH4 • 4 pairs v. e- • 4 pairs v. e- bonding • Note that the bond Angle is greater than 900 its 109.50
Lewis diagram NH3 • How many v e- pairs around central atom? • How many bonding V e- pairs around central atom?
Trigonal-Pyramid • 4 pairs v e- • 3 pairs bonding • Pyramid geometry • Like tetrahedral with one atom removed.
Lewis Diagram H2S • How many valence e- pairs around central atom? • How many bonding valence e- pairs around central atom?
Bent geometry • 4 v e- pairs • 2 pairs bonding • Like tetrahedral with two atoms removed
Lewis diagram CH2O • Pairs of e- around the central atom? 3 …double or triple bonds must act as a single pair. • How many atoms bonded to central atom? 3…
Trigonal-Planar • Triangular geometry • 3 pairs of e- and 3 bonding. • 1200 bond angle.
Lewis diagram CO2 • e- pairs around the central atom? • TWO… double bonds act as one center of neg. charge. • atoms bonded to central atom? • TWO
CO2 Linear geometry • Two pairs of e-s or centers of neg. around the central atom. • 1800 is the furthest away from each other they can be…remember, its repulsion!
Diagram ONF • How many Centers of negative charge surround the central atom? • Three. • How many atoms bonded to central atom? • Two
ONF has Bent geometry • The groups of electrons orient to the corners of a triangle. Only two atoms are bonded…this gives us bent or angular geometry.
# groups of e-s # atoms bond around centerto centerGeometry 4 4 4 3 4 2 3 3 3 2 2 2