3.1.3.7 Forces Between Molecules

At any moment, oscillations produce an instantaneous dipole Instantaneous dipoles are created by other dipoles The dipoles attract each other Only attractive force between non-polar molecules Increased VdW forces = increased surface area / increased tesselation/ more electrons / increased chain length / area of contact They act between all molecules and atoms More electrons = more charge

Polar molecules line up so that they are attracted to opposing forces Act only between certain types of molecule Difference in charge increases the forces, larger difference in electronegativities = stronger the force Molecules have permanent dipoles which makes the bonds stronger than VdW

Hydrogen bonded to a very electronegative atom (O, N, F) Electronegative atom must have a lone pair of electrons which will be attracted to the partially positively charged hydrogen atom

As water cools, the hydrogen bonds spread to hold the negatively charged oxygen atoms apart

All directions

The lone pair of the electronegative atom is attracted to the electron deficient hydrogen atom