Shapes of Molecules

• 4 bonding, no lone pairs


  Tetrahedral

  
• 3 bonding, 1 lone pair


  Trigonal pyramidal

  
• 2 bonding, 2 lone pairs


  Bent

  
• 2 bonding, no lone pairs


  Linear

  
• 3 bonding, no lone pairs


  Trigonal planar

  
• 5 bonding, no lone pairs


  Trigonal bipyramidal

  
• 6 bonding, no lone pairs

  Octahedral

  
• Tetrahedral bond angle


  109.5

  
• Trigonal pyramidal bond angle


  107

  
• Bent bond angle

  104.5

  
• Linear bond angle


  180

  
• Trigonal planar bond angle

  120

  
• Trigonal bipyramidal bond angles


  90 and 120

  
• Octahedral bond angles

  90

  
• Electron pair repulsion theory


  A theory which explains the shapes of simple molecules by assuming that pairs of electrons around a central atom repel each other and thus take up positions as far away as possible from each other in space.

  
• 3 bonding pairs, 2 lone pairs


  T-shaped or trigonal planar

  
• 4 bonding pairs, 1 lone pair


  See-Saw

  
• 4 bonding pairs, 2 lone pairs


  Square planar

  
• 5 bond pairs, 1 lone pair


  Square based pyramid

  
• 4 bonding, no lone pairs


  Tetrahedral

  
• 3 bonding, 1 lone pair


  Trigonal pyramidal

  
• 2 bonding, 2 lone pairs


  Bent

  
• 2 bonding, no lone pairs


  Linear

  
• 3 bonding, no lone pairs


  Trigonal planar

  
• 5 bonding, no lone pairs


  Trigonal bipyramidal

  
• 6 bonding, no lone pairs


  Octahedral

  
• Tetrahedral bond angle


  109.5

  
• Trigonal pyramidal bond angle


  107

  
• Bent bond angle


  104.5

  
• Linear bond angle


  180

  
• Trigonal planar bond angle


  120

  
• Trigonal bipyramidal bond angles


  90 and 120

  
• Octahedral bond angles


  90

  
• Electron pair repulsion theory


  A theory which explains the shapes of simple molecules by assuming that pairs of electrons around a central atom repel each other and thus take up positions as far away as possible from each other in space.

  
• 3 bonding pairs, 2 lone pairs


  T-shaped or trigonal planar

  
• 4 bonding pairs, 1 lone pair


  See-Saw

  
• 4 bonding pairs, 2 lone pairs


  Square planar

  
• 5 bond pairs, 1 lone pair


  Square based pyramid

  
• What theory is used to determine the shape of molecules?


  Valence Shell Electron Pair Repulsion (VSEPR) theory
• What is the key principle behind VSEPR theory?


  Electron pairs repel each other and arrange themselves as far apart as possible to minimize repulsion