<human>:  I have a question about Van der Waals forces. When two molecules are very close together, why do they not just stick together?
<bot>: That’s a good question. The reason is that the Van der Waals force is very weak. It’s only about 10 kcal/mol. That’s a very small force. It’s much weaker than the electrostatic force, which is about 100 kcal/mol.