Chap 6: Shapes of molecules and intermolecular forces

• Define a bonding pair


  -the two shared electrons in a covalent bond
• Define a lone pair


  -two electrons in a pair not involved in bonding
• Why do lone pairs repel more strongly than bonded pairs


  -lone pairs are closer to the central atom and occupy more space than a bonding pair
• outline the relative repulsons between lone and bonding pairs


  bp/bp<bp/lp<lp/lp
• As you add a lone pair what does the bond angle reduce by?


  -2.5 degrees
• If there are 2 pairs of e-s what is the name of the shape and the bond angle?

  -linear

  -180
• If there are 3 pairs of e-s what is the name of the shape and the bond angle?

  -trigonal planar

  -120
• If there are 4 pairs of e-s what is the name of the shape and the bond angle?

  -tetrahedral

  -109.5
• If there are 6 pairs of e-s what is the name of the shape and the bond angle?

  -octahedral

  -90
• What is the shape and angle of methane CH4


  -tetrahedral

  -109.5
• What is the shape and angle of ammonia NH3


  -Pyramidal

  -107
• What is the shape and angle of water H20


  -non-linear

  -104.5
• 2 bp and 1 lp


  -bent

  -118 degrees
• 2 bp 2 lp


  -bent

  -104.5
• 5 bp


  -trigonal bipyramidal

  -120 and 90
• 4bp 1 lp

  -trigonal pyramidal

  -88 and 118
• 3 bp 2 lp


  -trigonal planar

  -88 degrees OR 120 (depends on way drawn)
• 5 bp 1 lp


  -square pyramid

  -88
• 4 bp 2 lp


  -square planar

  -90
• sulphur can have up to

  • 12 e-s on its outer shell
• boron can have up to

  • 6 on its outer shell
• beryllium can have up to

  • 4 e-s on its outer shell
• phosphorus can have up to

  • 10 e-s on its outer shell