CHEM 1AA3 Lecture Notes - London Dispersion Force, Intermolecular Force, Polyelectrolyte
14 Feb 2014
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Chapter 12: exclude: sections 12. 7-12. 9, include: sections 12. 1(only capillary action),12. 2-12. 6 (much of which was discussed in chem 1a03 recall: properties of water, intermolecular forces = imf. In pure substances: van der waals forces, dipole-dipole forces, hydrogen-bonding forces. In solutions we also see: ion-dipole forces, ionic interactions e. g. , iodine e. g. , acetone e. g. , water e. g. , hydrated ions e. g. , hydrated ions. 1aa3: van der waals forces increases with: Atomic number and size of the molecule (due to polarizability) Linear versus branched structures (due to increased intermolecular contact area) 1aa3: occur in polar molecules (molecules with permanent dipoles) Polar molecules have bond dipoles and asymmetric shape: being polar increases b. p. over dispersion forces alone. E. g. , n2 (77k), no (121 k), o2 (90 k) 12. 6: hydrogen bonding: between an h atom in a polar bond (i. e. , h-n, h-o, or h-f) and another electronegative atom (i. e. , n, o, or f, one h-bond is small, but many are mighty, 495.
