Hydrogen bridges

This intermolecular interaction can also be called hydrogen bonds.

It is always held between hydrogen and a more electronegative atom, such as fluorine, oxygen and nitrogen.

It is characteristic in polar molecules. They can be found in solid and liquid state.

It is the strongest bond of all, due to the high electropositivity of hydrogen and the high electronegativity of fluorine, oxygen and nitrogen.

On the one hand a very positive atom and on the other a very negative atom. This makes the attraction between these atoms very strong. Therefore, they are usually solid or liquid. Examples:

H2O, HF, NH3

One consequence of the hydrogen bridges that exist in water is their high superficial tension. The molecules inside the liquid attract and are attracted to all neighboring molecules, so that these forces balance each other.

Already the surface molecules are attracted only by the molecules below and the sides. Consequently, these molecules attract each other more strongly and create an elastic film-like film on the water surface.

This phenomenon occurs with all liquids, but with water happens more intensely.

Surface tension explains some phenomena, such as the fact that some insects walk on water, and the spherical shape of water droplets.