Definition of Hydrogen Bridge

Hydrogen bonding takes place under three different circumstances.

1) when electrons are shared between two atoms,

2) when a force from attraction between an atom with electric charge negative 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 of a molecule with a hydrogen atom that is covalently bonded to another electronegative atom in a molecule that is close.

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 for hydrogen bonds and it does not matter if they are covalently bonded to a hydrogen atom or not. hydrogen.

In this sense, the Water is a covalent molecule and has hydrogen bonding 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 constitute 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 characteristic singular: these polar molecules have to contain hydrogen that is bound to other elements of high electrical negativity, as happens with fluorine, oxygen and nitrogen.

Finally, the dispersion forces, also known as London forces, are 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 charges electrical attraction occurs, as an apolar molecule induces the dipole of another molecule and this causes an intermolecular bond, as it happens with gases apolar when there is a change from gas to liquid through liquefaction).

Photos: Fotolia - kali1348 / molekuul

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