Year 12s: what will be the first way you research your future options? >>

van der Waals question

I understand the concept of instantaneous induced dipoles. However, I don't understand how this is an attractive force because shouldn't it be just as repulsive as it is attractive? Shouldn't it be just as likely that a positive induced pole meets another positive induced pole (thus creating a repulsive force) as it is for a positive induced to pole to meet a negative induced pole?

Reply 1

Kallisto

Entertainment Forum Helper

Look at this picture:
http://practicalmaintenance.net/wp-content/uploads/Van-der-Waals-Bond.jpg

As you know the charges are 'shifted' for a certain time in both atoms. Atom A and atom B are arranged in a way that two different charges are opposing each other, so it comes to an attraction instead of a repulsion.