Shapes Of Molecules

Molecules with lone pairs
1. Pyramidal
  1. These molecules have 1 lone pair and 3 bonding pairs of electrons
    1. Examples are: Ammonia(NH3) - Bond angle of 107 degrees
2. Non-Linear/Bent
  1. These molecules have 2 lone pairs and 2 bonding pairs of electrons
    1. Examples are: Water(H2O) - Bond angle of 104.5 degrees
3. If a molecule is tetrahedral, 1 lone pair will make it pyramidal
  1. Adding another lone pair to this will result in a non-linear/bent shape
4. A lone pair of electrons is more electron dense than a bonded pair
  1. As such, each lone pair reduces the bond angle by about 2.5 degrees
Molecules without lone pairs
1. Linear
  1. These molecules have 2 bonding pairs of electrons
    1. Examples are: H2 or CO2 - Bond angle of 180 degrees
2. Trigonal Planar
  1. These molecules have 3 bonding pairs of electrons
    1. Examples are: BF3 - Bond angle of 120 degrees
3. Trigonal Bipyramid
  1. These molecules have 5 bonding pairs of electrons
    1. Examples are: PCl5 - Bond angles of 90 and 120 degrees
      1. The angle between the vertical bond and horizontal bond is 90 degrees. However, the angle between each horizontal bond is 120 degrees
4. Octahedral
  1. These molecules have 6 bonding pairs of electrons
    1. Examples are: SF6 - Bond angle of 90 degrees
5. Tetrahedral
  1. These molecule have 4 bonding pairs of electrons
    1. Examples are: Methane - CH4 - Bond angle of 109.5 degrees
Shapes of ions
1. The principles about molecular shapes can be applied to ionic shapes
2. As such in the example of an ammonium ion - NH4, the shape is tetrahedral
  1. Thus meaning that it has 4 bonding pairs of electrons
    1. However, it will also need to be surrounded by square brackets and have the displayed charge as it is an ionic molecule

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Shapes Of Molecules

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	Created by Alexander Boon about 9 years ago