Intermolecular Forces

Intermolecular Forces:

These hold molecules together and are very weak; there are three types of these forces…

1.       Instantaneous Dipole – Induced Dipole (London Forces) à Weakest of the three

2.       Permanent Dipole – Permanent Dipole interactions

3.       Hydrogen Bonding (strongest of the three)

 London forces act between all atoms and molecules à electrons in charge clouds move quickly, more one sided creates temporary dipoles which creates chain reaction of temporary dipoles (domino effect). The dipoles are constantly created/destroyed so move, overall attraction between atoms or molecules.

Stronger London forces = higher mpt and bpt

·         Liquids with stronger LFs have higher bpts as more energy needed to overcome forces

 
Solids melting also have higher mpt if stronger forces alkanes…