Hydrogen bonding takes place under three different circumstances.
1) when electrons are shared between two atoms,
2) when an attractive force occurs between a negatively charged atom of a molecule and a hydrogen atom covalently bonded to another negative atom of another molecule or
3) when an atom picks up electrons from another atom.
In this way, it could be stated that a hydrogen bridge is the attractive force between an electronegative atom in a molecule with a hydrogen atom that is covalently bonded to another electronegative atom in a nearby molecule.
The hydrogen bridge in the case of water
The hydrogen bond is the result of the formation of a force with a hydrogen atom attached to a nitrogen, oxygen or fluorine atom, which are especially electronegative atoms and are receptors of hydrogen bonds and it does not matter if they are bonded. covalent or not to a hydrogen atom.
In this sense, water is a covalent molecule and has a hydrogen bond between the hydrogens of one molecule and the oxygens of the next molecule, and for this reason water forms networks that give it unique properties. In this way, if the hydrogen bond in the water were not, its high boiling point could not be explained, nor its surface tension.
Intermolecular links
Intermolecular bonds are the interactions between individual molecules of a substance. From these interactions it is possible to explain the properties of liquids (for example, the boiling point) and of solids (for example, the melting point).
There are three intermolecular bonds: the dipole-dipole bond, the hydrogen bond and the dispersion forces.
The dipole-dipole bond refers to positive and negative polar molecules that interact and establish an electrical attractive force between them. The hydrogen bridge bond is a type of dipole-dipole bond, which means that it occurs between polar molecules, but with a unique characteristic: these polar molecules have to contain hydrogen that is bound to other elements of high electrical negativity, just as it happens with fluorine, oxygen and nitrogen.
Finally, the dispersion forces, also known as London forces, are forces much weaker than the previous two and have a relevant characteristic: they are forces that are established between apolar molecules, that is, without poles or without electric charges (although there are no electric charges, the attraction occurs, since an apolar molecule induces the dipole of another molecule and this causes an intermolecular bond, as happens with apolar gases when a change from gas to liquid occurs through liquefaction).
Photos: Fotolia - kali1348 / molekuul
