•Permanent dipole-dipole forces occurs between polar molecules •It is stronger than van der waals and so the compounds have higher boiling points •Polar molecules have a permanent dipole. (commonly compounds with C-Cl, C-F, C-Br H-Cl, C=O bonds) •Polar molecules are asymmetrical and have a bond where there is a significant difference in electronegativity between the atoms.
Permanent dipole forces occurs in addition to van der waals forces
3.1.3.7 Forces between molecules
Forces between molecules:
• permanent dipole–dipole forces
The melting and boiling points of molecular substances are influenced by the strength of these intermolecular forces.
Students should be able to:
• explain the existence of these forces between familiar and unfamiliar molecules
• explain how melting and boiling points are influenced by these intermolecular forces.
1.3 Bonding Page 6
Oxford Textbook Pages : 54 - 55
CGP Revision Guide Pages : 30
