Different types of intermolecular forces (interaction between two different or two similar molecules) are written below-
A hydrogen bond is basically an electrostatic force of attraction between a hydrogen atom, which is covalently bonded to an electronegative atom, with another electronegative atom from the same or different molecule known as a hydrogen bond acceptor.
The most familiar hydrogen bond acceptors and donors are oxygen, nitrogen, fluorine which have greater electronegativity.
Both types of hydrogen bonding are known in chemistry as intermolecular and intramolecular hydrogen bonding. The bond dissociation energy or bond energy of a hydrogen bond depends on the nature of the acceptor, donor atoms, geometry and environment. It varies from 1kcal/mol to 40kcal/mol.
Hydrogen bond is comparatively stronger than Vander Waals force but weaker than covalent bond.
Van Der Waals Force
The van der Waals force is a distance-dependent molecular force, relatively weaker than ionic and covalent bonds. This is a shortrange force, and disappears as the distance between the two molecules increases.
This force includes both attractive and repulsive forces between two atoms or molecules. As a result of correlations in the fluctuating polarizations, the Vander Waals force arises.
The bond dissociation energy of van der Waals force ranges from 0.4 KJ/mol to 4 KJ/mol and this force depends on the relative orientation of the molecules.
The ionic bond
Ionic bond is basically a type of electrovalent bond. This bond is formed by electrostatic attraction between positively and negatively charged species. Permanent electron transfer is the main criterion for forming an ionic bond.
As a result of the permanent transfer of electrons, one atom becomes positively charged and the other negatively charged.
In general, alkali and alkaline earth metals participate in ionic bond formation due to their electropositive character.
The ionic bond is one of the strongest intermolecular forces in chemistry. The binding energy of an ionic bond is in the range of 170 to 1500 KJ/mol.
It is a chemical bond formed by the sharing of electron pairs between two identical or two different atoms. This sharing of electrons is not always the same between two atoms.
The electronegativity of the participating atoms has a great influence on the formation of a covalent bond. Atoms that are more electronegative attract more electron pairs to themselves than atoms that are less electronegative.
It is a relatively strong chemical bond with a bond dissociation energy of 80 kcal/mol. There are three types of covalent bonds in chemistry. Single bond or sigma bond, double bond or pi bond and last triple bond is formed by one sigma and two pi bonds.
The negative side of one polar molecule and the positive end of the other polar molecule participate in dipole-dipole attraction due to electrostatic attraction. The dipole-dipole interaction is much weaker than the covalent and ionic interactions.
The two opposite ends of a polar molecule or a dipole are the positive part and the negative part. These two parts participate in this dipole-dipole interaction.
The dipole-dipole interaction has a strength of about 5 KJ to 20 KJ/mol.
The dipole-dipole interaction depends on the distance and angle between the two circles and their relative speed.
An ion-dipole interaction arises due to the electrostatic interaction between a charged species (ion) and a permanent dipole (polar molecule). A cation (positively charged species) is attracted to the negative end of a polar neutral molecule and an anion (negatively charged species) is attracted to the positive end of a neutral but polar molecule.
The amount of positive or negative charge and the greater the charge density of any ion the stronger the ion dipole interaction. It is comparatively stronger than the dipole-dipole interaction and hydrogen bonding.
ion induced dipole interaction
The ion is a charged species and can induce (disturb the arrangement of the internal electrons) any non-polar and neutral molecule. Thus a negatively polarized and a positively polarized end will be created in that molecule after induction by the ion.
The charge of the ion distorts the electron cloud of the non-polar molecule and as a result the molecule becomes partially charged.
The strength of the ion-induced dipole interaction increases with the amount of charge and the charge density of the ion. It is stronger than the dipole-dipole interaction.
london dispersion force
The London dispersion force is the interaction between an induced dipole and an instantaneous dipole. The London dispersion force is a type of very weak intermolecular force between two molecules when they are in close proximity to each other.
This dispersion force arises when electrons from two adjacent atoms are oriented in such a way that the atom becomes a temporary dipole. The constant movement of atoms or molecules can cause instantaneous dipoles due to the asymmetric deformation of the electron cloud around the nucleus.
Hydrogen bonding, dipole-dipole interactions, dipole-induced dipole interactions are stronger than the London dispersion force.
Frequently Asked Questions
What causes intermolecular forces between molecules?
Most of the intermolecular forces are electrostatic in nature. They arise due to the attraction between two oppositely charged species.
What factors affect intermolecular forces?
The strength of attraction between molecules is the most important determining factor of intermolecular forces. In addition to temperature, pressure, kinetic energy, intermolecular forces between molecules have an effect.
Are intermolecular forces weaker than intermolecular forces?
Yes, intermolecular forces are weaker than intermolecular forces because the attraction between molecules that helps hold atoms together in the same molecular species is stronger than the attraction that Helps to hold between two different molecular species.