Nucleophillic substitution

Halogenoalkanes:

• Their C--X bond is polar because halogens are more electronegative than carbon. Halogens become less electronegative as you go down the group.
• Their polar bonds are not polar enough to allow the halogenoalkanes to be soluble in water, but mixing them with hydrocarbons allows then to be used as dry cleaning fluids.
• Boiling point increases with increased chain length because there are more electrons so stronger van der Waals forces - increased branching of the chain will lower melting point.
• The bonds get weaker as you go down the group because the larger the atom, the further away the shared…