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bond angle: ?. Chapter 9: Molecular Geometry and Bonding Theories. What determines molecular shape ?. Bond angles : angle formed between two adjacent bonds on the same atom. e.g. CCl 4. Chapter 9: Molecular Geometry and Bonding Theories. What determines molecular shapes ?.
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bond angle: ? Chapter 9: Molecular Geometry and Bonding Theories What determines molecular shape? Bond angles: angle formed between two adjacent bonds on the same atom e.g. CCl4
Chapter 9: Molecular Geometry and Bonding Theories What determines molecular shapes? => tell us how atoms are physically connected Lewis Structures No information regarding the actual 3-D structure of molecules
Chapter 9: Molecular Geometry and Bonding Theories Repulsion of valence electrons => largest possible separation of atoms Valence-Shell Electron-PairRepulsion Model
Chapter 9: Molecular Geometry and Bonding Theories Different ways of depicting 3-D structure bonds in plane of paper bond behind of the paper plane "Ball and Stick" "Spacefilling" bond in front of the paper plane
Chapter 9: Molecular Geometry and Bonding Theories Lewis structures show number of electron domains nonbonding pair Types of Electron Domains: • nonbonding (or "lone") electrons • single OR double OR triple bonding electrons => BondingANDnon-bonding electron pairs take up space bonding pair
Chapter 9: Molecular Geometry and Bonding Theories Molecular shape depends on electron domain geometry Lewis Structures tell us … • where bonds (bonding electron pairs) are • the location of nonbonding electrons } around the central atom Bonding AND non-bonding electron pairs take up space
180o 120o 109.5o 120o 90o 90o 90o Chapter 9: Molecular Geometry and Bonding Theories Possible Electron Domain Geometries: Linear Trigonal Planar Tetrahedral Trigonal Bipyramidal Octahedral
Chapter 9: Molecular Geometry and Bonding Theories Lewis structures →electron domain geometry→molecular geometry 4 electron domains around central atom => electron domain geometry: Tetrahedral nonbonding pair bonding pair 3 non-bonding + 1 bonding electron domain
Chapter 9: Molecular Geometry and Bonding Theories Lewis structures →electron domain geometry→molecular geometry 4 electron domains around central atom => electron domain geometry: Tetrahedral
Chapter 9: Molecular Geometry and Bonding Theories Lewis structures →electron domain geometry→molecular geometry 3 electron domains around central atom => electron domain geometry: Trigonal planar
Chapter 9: Molecular Geometry and Bonding Theories Lewis structures →electron domain geometry→molecular geometry 2 electron domains around central atom => electron domain geometry: Linear
Chapter 9: Molecular Geometry and Bonding Theories Lewis structures →electron domain geometry→molecular geometry 3 electron domains around central atom => electron domain geometry: Trigonal planar
Chapter 9: Molecular Geometry and Bonding Theories Lewis structures → electron domain geometry →molecular geometry Molecular Geometry depends on how many of the electron domains are actually bonds 4 electron domains: => electron domain geometry Tetrahedral 3 bonds, 1 nonbonding pair: => molecular geometry Trigonal pyramidal
Chapter 9: Molecular Geometry and Bonding Theories Bond angles can be distorted: 109.5 o 107 o 104.5 o • nonbonding electron pairs occupy more volume than bonding pairs
Chapter 9: Molecular Geometry and Bonding Theories Bond angles can be distorted 125.3 o 111.4 o 125.3 o • multiple bonds occupy a larger volume than single bonds Volume Volume lone pairs => triple bonds => double bonds => single bonds
e.g. phosphorous: P: [Ne] 3s2 3p3 3s 3p 3d "expanded" valence shell Chapter 9: Molecular Geometry and Bonding Theories Elements from the 3rd period onward.. • have d -orbitals • can have an expanded valence shell • may have more than 4 electron domains surrounding them
Chapter 9: Molecular Geometry and Bonding Theories Equatorial bond Axial bond
Chapter 9: Molecular Geometry and Bonding Theories electron domain geometry molecular geometry # electron domains TeF6
+ Chapter 9: Molecular Geometry and Bonding Theories electron domain geometry molecular geometry # electron domains H3O+
Chapter 9: Molecular Geometry and Bonding Theories electron domain geometry molecular geometry # electron domains NO2
Chapter 9: Molecular Geometry and Bonding Theories electron domain geometry molecular geometry # electron domains SO3
Chapter 9: Molecular Geometry and Bonding Theories electron domain geometry molecular geometry # electron domains SCl2
Chapter 9: Molecular Geometry and Bonding Theories electron domain geometry molecular geometry # electron domains SbI5
? ? ? Chapter 9: Molecular Geometry and Bonding Theories The VESPR model can be extended to larger molecules e.g. glycine : ? predicted bond angles: Electron-domain geometry:
