Physical Properties of some functional groups: Intermolecular forces and water solubility

The strength of intermolecular forces in molecules with functional groups depends on:

• polarity
• capability of hydrogen bonding

\ Organic molecules can be:

1. Nonpolar

       1. the strongest IMF in nonpolar molecules is $dispersion forces$    2. nonpolar organic molecules include hydrocarbons, alkanes, alkenes, alkynes, aromatic hydrocarbons

2. Polar

       1. strongest force of attraction between molecules is $dipole-dipole interactions$    2. organic molecules with oxygen & nitrogen are usually polar molecules

3. Capable of hydrogen bonding

       1. include alcohols, amines, carboxylic acids, amides    2. strongest attractive force in all of functional groups

\ Order of boiling points (1 is highest BP and 4 is lowest BP):

1. carboxylic acids & amides
2. alcohols
3. aldehydes & ketones
4. hydrocarbons & ethers

\ Order of water solubility (1 is highest and 5 is lowest):

1. carboxylic acids & amides
2. alcohols
3. aldehydes & ketones
4. ethers (this is because ethers can accept hydrogen bonding while hydrocarbons can’t)
5. hydrocarbons

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