shapes of molecules and imfs

• bonded pair and lone pair repulsions

  lp is slightly closer to central atom and occupies more space than bp which results in a lp repelling more strongly than a bp
• tetrahedral

  4 bp

  0 lp

  bond angle 109.5

  AX4
• pyramidal

  3 bp

  1 lp

  bond angle 107

  AX3
• non linear

  2 bp

  2 lp

  bond angle 104.5

  AX2
• linear

  2 bp

  0 lp

  bond angle 180

  AX2
• trigonal planar

  3 bp

  0 lp

  bond angle 120

  AX3
• trigonal bipryamidal

  5 bp

  0 lp

  bond angle 120, 90

  AX5
• octahedral

  6 bp

  0 lp

  bond angle 90

  AX6
• polar vs non polar

  polar if the electron pair is shared unequally between bonded atoms

  non polar if shared equally, charges balance out
• induced dipole-dipole forces

  movement of electrons produce a changing dipole in a molecule, temporary

  more electrons in a molecule = stronger attractive forces = higher boiling point as more energy needed to overcome the imfs
• permanent dipole-dipole interactions

  act between permanent dipoles in different polar molecules
• hydrogen bonding

  a type of permanent dipole-dipole interaction found between an electronegative atom with a lone pair of electrons and a hydrogen atom attached to an electronegative atom
• anomalous properties of water

  solid is less dense than liquid (due to H bonds holding molecules in open lattice structure)

  relatively high melting point and boiling point (H bonds require lots of energy to overcome)