Intermolecular forces are those responsible for keeping molecules together in the formation of different compounds, they are classified as:
Dipole-induced force: it is caused by the accumulation of electrons in a certain region of the molecule.
The intermolecular interactions present in nonpolar molecules are dipole-induced, but they do not occur all the time, the distribution of electrons in the electrosphere of these molecules is uniform. However, at some point there is an accumulation of charges δ + and δ - (poles) at the ends, this is where the forces dipole-induced appear, and as the name implies, they induce neighboring molecules to also enter into imbalance.
See examples of nonpolar compounds whose molecules interact through dipole-induced forces:
Cl2, CO2, CH4, H2, O2
Dipole-dipole forces: intermolecular force present in polar compounds.
δ + δ- δ + δ- δ + δ-
H? Br H? Br H? br
Note that in hydrobromic acid (HBr) molecules there are poles δ + and δ-, they are responsible for this molecule being polar.
Examples of polar compounds in which dipole-dipole interaction occurs:
H2S, CO, SO2, HCl
Hydrogen bonds: This is the strongest interaction that occurs between molecules, compared to the much more enhanced dipole-dipole strength. This bond occurs between molecules that contain hydrogen atoms bonded to nitrogen atoms, fluorine, oxygen, that is, very electronegative elements, so the δ + and δ- poles are more accented.
The water molecule is a classic example of hydrogen bonds, where H atoms bond tightly with the H atoms of other molecules to form the H chain.20.
See which intermolecular force is more intense through the figure below:
The arrow indicates the ascending order of interaction intensity.
By Líria Alves
Graduated in Chemistry
Brazil School Team
See more:
Intermolecular forces and solubility
Experiment that allows testing which substance is polar and non-polar.
General chemistry - Chemistry - Brazil School
Source: Brazil School - https://brasilescola.uol.com.br/quimica/tipos-forcas-intermoleculares.htm