And if the force is large, this interaction is very strong. And this type of interaction between the H atom of one water molecule and the oxygen atom of another water molecule is known as a hydrogen bond. So, once again, water molecules interact strongly with other water molecules via electrical forces or, to be more specific, electromagnetic forces. Now, the small size of the positively charged hydrogen atom of one molecule, for example, let's say this molecule allows it to get very close to the negatively charged oxygen of another molecule. For example, this molecule right here, the small size of this allows it to get very close to this oxygen. And this small distance basically means we have a very strong interaction.