Now, why is a hydrogen bond the most stable, the strongest type of inter molecular bond? Well, that's because hydrogen is the smallest nucleus that exists in nature and it's such a small atom that the H atom can get very close to this atom and this atom. And so what that means is because the distance between the two charges is so small that force is relatively large and that's exactly why hydrogen bonds are the strongest type of intermolecular bonds. Now, another terminology that you have to be familiar with in your study of biochemistry is what it means for a group of atoms to be an H bond donor and what it means to be an Hbond acceptor. So if we examine the following interaction this group of atoms is our H bond donor and this is the Hbond acceptor. This is the H bond donor and this is the H bond acceptor.