7 Intermolecular Forces Examples: Detailed Explanations


In this article “intermolecular forces examples”, the different types and examples of the intermolecular forces are explained briefly.

The different types of intermolecular forces (interaction between two different or two same molecules) are written below-

Hydrogen Bond

Hydrogen bond is basically an electrostatic force of attraction acts between one hydrogen atom, covalently bonded with an electronegative atom, with another electronegative atom known as hydrogen bond acceptor from same or different molecule.

The most familiar hydrogen bond acceptor and donor is Oxygen, nitrogen, fluorine having greater electronegativity.

Both type of hydrogen bonding is known in chemistry, that is intermolecular and intramolecular hydrogen bonding.  The bond dissociation energy or bond energy of a hydrogen bond depends on the nature of 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 bonding.

intermolecular forces examples
Hydrogen Bonding in Water Molecule.
Image Credit: Wikimedia Commons

Van der Waals Force

Van der Waals force is a distance dependent molecular force, which is relatively weaker than ionic and covalent bonding. It is a shortrange force, and vanishes when the distance between two molecule increases.

This force includes both the attractive and repulsive force between two atoms or molecules. As a result of correlations in the fluctuating polarizations, the vanderwaals force is generated.

The bond dissociation energy of Van der Waals force is from 0.4 KJ/mol to 4 KJ/mol and this force depends upon the relative orientation of the molecules.

Van der Waals Force increases with the increase of surface area.
Image Credit: Wikimedia Commons

  To know more please follow: 4 nonpolar covalent bond examples: Detailed Insights And Facts

Ionic Bonding

Ionic bonding is basically one type of electrovalent bond. This bond is formed between positively and negatively charged species by the electrostatic attraction. Permanent electron transfer is main criteria to form the ionic bonding.

 As a result of permanent transfer of electrons, one atom becomes positively charged and another will be negatively charged.

In general alkali and alkaline earth metals participate in ionic bond formation due to their electropositive character.

Ionic bonding is one of the strongest intermolecular forces in Chemistry. The bond energy of an ionic bond is in the range of 170 to 1500 KJ/mol.

Sodium Chloride, an Ionic Compound.
Image Credit: Wikimedia Commons

To know more please go through: 10 Ionic Bond Examples: Explanation And Detailed Facts

Covalent Bonding

It is a chemical bond formed between two same or two different atoms by sharing of electron pairs. This sharing of electrons is not always equal between two atoms.

Electronegativity of the participating atoms have a great impact on formation of covalent bond. More electronegative atom attracts the electron pairs in a greater extent towards itself than the less electronegative atoms.

It is relatively stronger chemical bond having bond dissociation energy 80 kcal/mol. There are three types of covalent bond in Chemistry. Single bond or sigma bond, double bond or pi bond and the last one is triple bond formed by one sigma and two pi bonds.

Dipole-Dipole Interaction

Negative part of one polar molecule and positive end of another polar molecule participate in the dipole-dipole attraction due to electrostatic attractive force. Dipole-dipole interaction is much weaker than covalent and ionic interaction.

Polar molecule or any dipole has two opposite end positive part and negative part. These two parts participate in this dipole-dipole interaction.

Dipole-dipole interaction has the strength of about 5 KJ to 20 KJ/mol.

Dipole-dipole interaction depends upon the types of the spins, distance and angle between the two spins and the relative motion of them.

Dipole-Dipole Interaction.
Image Credit: Wikimedia Commons

To know more please check: N2 polar or nonpolar: Why, How, Characteristics, And Detailed Facts

Ion-Dipole Interaction

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) attracts the negative end of the polar neutral molecule and an anion (negatively charged species) attract the positive end of a neutral but polar molecule.

The amount of positive or negative charge and larger charge density of any ion strengthens the ion dipole interaction. It is comparatively stronger than dipole-dipole interaction and hydrogen bond also.

Ion Dipole Interaction.
Image Credit: Wikimedia Commons

Ion-Induced Dipole Interaction

Ion is a charged species and it can induce (disturbing the arrangement of the inner electrons) any nonpolar and neutral molecule. Thus one negatively polarized and a positively polarized end will be created in that molecule after the induction by the ion.

The charge of the ion distorts the electron cloud of the nonpolar molecule and as a result the molecule becomes partially charged.

 Amount of charge and charge density of ion increases the strength of ion-induced dipole interaction. It is stronger than the dipole-dipole interaction.

London Dispersion Force

London Dispersion Force is the interaction between one induced dipole and instantaneous dipole.  London dispersion force is a type of very weak intermolecular force between two molecules when they are in close proximity with each other.

This dispersion force is generated when the electrons from two adjacent atoms orient in such way that makes the atom into a temporary dipole. The constant motion of the atoms or molecules can cause an instantaneous dipole due to the unsymmetrical distortion of the electron cloud around the nucleus.

 Hydrogen bonding, dipole-dipole interaction, dipole-induced dipole interaction are stronger than the London dispersion force.

London Dispersion Force.
Image Credit: Wikimedia Commons

  To know more please follow: Properties of Peptide bond: Detailed Fact and Comparative Analysis

Frequently Asked Questions (FAQ)

What causes the intermolecular forces between the molecules?

Answer: Most of the intermolecular forces are electrostatic in nature. They are generated due to the attraction between two oppositely charged species.

Which factors affect the intermolecular forces?

Answer:  The strength of attraction between the molecules is the most important determining factor of intermolecular forces. Besides of temperature, pressure, kinetic energy have an impact of intermolecular forces between the molecules.

Are intermolecular forces weaker than the intramolecular forces?

Answer: Yes, intermolecular forces are weaker than the intramolecular forces because the attraction between the same molecule that helps to hold the atom together in the same molecular species is stronger than the attraction that helps to hold between two different molecular species.

Aditi Roy

Hi..I am Aditi Roy, I have completed my graduation from University of Calcutta and am pursuing M.Sc in Chemistry from Techno India University. My area of specialization is on Inorganic Chemistry.

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