What are the different types of Van der Waals forces with examples and differences
Van Der Waals forces are the interactions between atoms and molecules that result in a pull between them. These forces consist of weak intermolecular interacting with each the nearest possible distance. The molecules do not contain any charge.
These interactions or bonds comprise of three types, such as dipole-dipole, hydrogen bonds and London dispersion forces. Their formation depends on the type of bonding between molecules.
The concept of Waals’ interactions is vast. It requires a deeper understanding of the properties and types to score better! So, go through the below pointers to get a hold of Van Der Waals interactions.
Let’s start!
Types of Van Der Waals Bonding
The Waals’s interactions depend on three types of forces, such as London forces, dipole-dipole and hydrogen bonding. They are based on the type of bonding they share within molecules or atoms. These include:
Dipole-Dipole Interactions
These bonds lead to the formation of attractive forces present in the two polar molecules having constant dipoles. These dipoles occur when atoms present close to each other contain an electronegative effect. Its occurrence results from the interaction of a molecule’s negative portion with the positive part of the other molecule.
The dipoles having opposite charges form a firm bonding among them as they attract each other with stronger forces. A molecular dipole forms when electrons share an unequal distribution within themselves.
Hydrogen chloride (HCl) is an appropriate example of Van Der Waals forces containing dipole-dipole interactions as it contains both positive and negative ends attracting others. Moreover, a molecule of HCl comprises a permanent dipole as the chlorine atom present in it is more electronegative than the hydrogen one.
London Dispersion Forces
These interactions share the weakest type of bonding among the three types of Waals forces. Their attractions arise from the short-term and induced dipoles available in most molecules and atoms. The dispersion forces are also responsible for creating dipole-induced dipole bonds.
These bonds occur when electrons available within two adjoining atoms take interim positions. They are also accountable for condensation of non-polar materials into liquids, and freezing of solid when the temperature drops. Mostly, these interactions depend on the molecules’ ability to polarize.
These weakest intermolecular forces also occur within two or more molecules when the polar ones get situated nearby. Their strength varies along with the number of electrons occurring in a molecule. Mostly, these interactions occur due to the motion of these electrons.
Hydrogen Bonding
These forces occur from a unique type of dipole-dipole interactions inside two or more hydrogen atoms. Their attractions are relatively much stronger than London dispersion forces and dipole-dipole interactions. The attractions between hydrogen bonds occur because of the strong forces between a hydrogen atom.
These atoms share a covalent type of bonding between two highly electronegative atoms, such as Oxygen, Nitrogen and Fluorine, etc. The hydrogen molecules form stronger bonds by getting attracted to O, F and N atoms, but only these atoms can form bonds with hydrogen atoms. The strength of a hydrogen bond varies between 4 kJ/mol and 50 kJ/mol.
Did you know: Interaction between water molecules is an appropriate example of Hydrogen bonding of Van Der Waals forces!
Pop Quiz 1
Solve the below question to brush up your skills!
Under what circumstances, does a real gas work closely in the ideal gas equation of Vander waal forces?
There is less pressure and higher temperature.
Both pressure and temperature are high.
Pressure appears higher, and the temperature is low.
Both pressure and temperature are low.
None of the above.
Van Der Waals Equation
While learning about the Van Der Waals forces, it is essential to know regarding its equation. The Waals equation depicts the characteristics of two real gases. It studies the excluded volume of these gases and its intensity of attraction occurring between them.
It gets elucidated as:
(P+n2aV2) (V-nb)= nRT
Where a = intensity of attraction between two or more molecules or atoms.
And b = excluded volume of real gases.
Activity: Find how molecular shape plays a vital role in impacting the strength of dispersion forces? Take expert’s guidance if necessary.
Components of Waals Interactions
The Van Der Waals forces appear as an interaction in a closely-situated position of the molecules or atoms. These forces depend on the attractions or repulsions within two or more molecules. The bonds get firmer when they occur with a short distance from 0.4 kilojoules per mole (kJ/mol) to 4 kJ/mol.
However, their pull tends to repel when situated at a distance less or within 0.4 nanometers (nm). Mostly, they appear to be highly active when they get situated at a space of less than 0.6 nanometers.
Try reading the below pointers to gain knowledge about the components of Van Der Waals bonding. They are as follows:
These bonds contain negative components that prohibit molecules from collapsing with each other. It is due to the Pauli Exclusion Principle.
The Keesom force is another key contributor to Waals interactions. There exists either repulsion or attractive interaction between dipoles, multi-poles, quadrupoles or constant charges due to the Keesom.
London dispersion force forms a vital component of the Waals bond. It arises due to the interaction between nonpolar or polar molecules.
Debye force also acts as a key contributor in the Waals forces. It is accountable for the occurrence of attractions between molecules containing an induced and permanent polarity.
Properties of Van Der Waals Bonding
Read the characteristics of Waals forces to know more of them in detail!
These interactions contain comparatively weaker, electric bonds compared to the ionic, covalent or metallic interactions.
These attractions or forces remain completely unaffected by the change in temperature apart from dipole-dipole interactions.
The attractions become addictive as it contains a huge number of molecules available with them. They are still present when the molecules get placed at a long distance.
These weak bonds are present in almost all types of materials. However, primary bonds often overpower their effects as they are relatively weaker in comparison to them.
The Waals interactions are universal, and they are accountable for the attraction of atoms or molecules within themselves.
These intermolecular bonds work with a short-range. Hence, the interactions occur when the particles get closely situated with each other. The pace of attraction is greater when the molecules or atoms get closer to each other.
Additionally, these intermolecular forces do not have the capability of saturation.
Moreover, these interactions do not possess any directional attributes.
Activity: Study the applications of these bonds in detail and try to find some suitable Van Der Waals forces examples. Take the help of your friends or teachers for additional guidance.
Interesting Facts about Waals Forces
The Waals forces are the weakest intermolecular interactions.
These bonds derive their name from a Dutch Scientist known as Johannes Diderik Van Der Waals. He found the existence of these forces while understanding the theory of a real gas in 1873.
The forces working between two dipoles are known as Keesom. It derives its name from William Hendrik Keesom.
The attraction operating between a molecule containing charge and a dipole is known as Debye. It derives its name after Peter Debye.
The Van Der Waals equation studies the properties of two gases.
The word ‘a’ in the Waals equation shows the intensity of attraction among molecules or atoms.
The firmness of a hydrogen bond varies from 4 kJ/mol to 50 kJ/mol.
Only Nitrogen, Oxygen and Fluorine atoms in a single molecule can form hydrogen bonding.
The interactions between two polarized particles are known as London forces. They derive their name after Fritz London.
Chemistry is a subject that requires in-depth knowledge of complex theories and formulas of various compounds. Therefore, you will feel the need for guidance when you get stuck with problematic areas. For easing out such problems, you can take help of our live classes and learn more engaging concepts similar to Van Der Waals forces in chemistry.
FAQs on Understanding the Types of Van der Waals Forces in Chemistry
1. What are Van der Waals forces in chemistry?
Van der Waals forces are weak intermolecular forces of attraction that exist between molecules due to temporary or permanent dipoles. These forces are much weaker than covalent or ionic bonds but significantly influence physical properties like boiling point and solubility.
They include:
- London dispersion forces (temporary dipole–induced dipole)
- Dipole–dipole interactions (between permanent dipoles)
- Dipole–induced dipole forces
Van der Waals forces explain why nonpolar molecules like O2 and N2 can condense into liquids at low temperatures.
2. What are the types of Van der Waals forces?
The three main types of Van der Waals forces are London dispersion forces, dipole–dipole interactions, and dipole–induced dipole forces. These intermolecular forces differ based on how molecular dipoles are formed.
- London dispersion forces: Caused by temporary fluctuations in electron density.
- Dipole–dipole forces: Occur between molecules with permanent dipoles (e.g., HCl).
- Dipole–induced dipole forces: Form when a polar molecule induces a dipole in a nonpolar molecule.
All molecules experience dispersion forces, but only polar molecules exhibit dipole–dipole interactions.
3. What are London dispersion forces?
London dispersion forces are weak intermolecular forces caused by temporary, instantaneous dipoles formed due to fluctuations in electron distribution. They are also called instantaneous dipole–induced dipole forces.
- Present in all atoms and molecules, including nonpolar ones.
- Strength increases with molar mass and surface area.
- Example: Attraction between nonpolar Cl2 molecules.
They are the only intermolecular forces present in noble gases like Ne and Ar.
4. What is the difference between dipole–dipole forces and London dispersion forces?
Dipole–dipole forces occur between molecules with permanent dipoles, while London dispersion forces arise from temporary dipoles in all molecules. The key difference is whether the dipole is permanent or temporary.
- Dipole–dipole: Found in polar molecules like HCl; generally stronger.
- Dispersion forces: Present in both polar and nonpolar molecules like CH4; usually weaker.
Polar molecules experience both dispersion and dipole–dipole forces.
5. What is a dipole–induced dipole force?
Dipole–induced dipole forces occur when a polar molecule induces a temporary dipole in a nearby nonpolar molecule. This interaction creates a weak attraction between them.
- The polar molecule has a permanent dipole.
- The nonpolar molecule becomes temporarily polarized.
- Example: Interaction between H2O and O2.
These forces are weaker than dipole–dipole interactions but stronger than pure dispersion forces in some cases.
6. Are hydrogen bonds a type of Van der Waals force?
Hydrogen bonding is a special, stronger type of dipole–dipole interaction but is often considered separately from Van der Waals forces. It occurs when hydrogen is bonded to highly electronegative atoms like N, O, or F.
- Example: Hydrogen bonding between H2O molecules.
- Stronger than typical dipole–dipole forces.
- Responsible for high boiling point of water.
In some classifications, Van der Waals forces exclude hydrogen bonding due to its relatively higher strength.
7. Why are Van der Waals forces important in chemistry?
Van der Waals forces are important because they determine physical properties such as boiling point, melting point, viscosity, and solubility. Even though weak, their cumulative effect can be significant.
- Explain condensation of nonpolar gases.
- Influence protein folding and biological structures.
- Affect intermolecular attractions in liquids and solids.
For example, larger molecules like I2 have stronger dispersion forces and higher boiling points than F2.
8. How does molecular size affect Van der Waals forces?
Van der Waals forces increase as molecular size and molar mass increase because larger molecules have more electrons and greater polarizability. More electrons allow stronger temporary dipoles to form.
- Greater electron cloud → higher polarizability.
- Larger surface area → stronger dispersion forces.
- Example: Boiling point increases from CH4 to C4H10.
Thus, heavier molecules generally experience stronger London dispersion forces.
9. Do nonpolar molecules have Van der Waals forces?
Yes, nonpolar molecules experience Van der Waals forces in the form of London dispersion forces. These forces arise from temporary fluctuations in electron density.
- Present in molecules like N2, O2, and CO2.
- Responsible for liquefaction of noble gases like Ar.
Without dispersion forces, nonpolar substances would not exist as liquids or solids.
10. How do Van der Waals forces compare to covalent and ionic bonds?
Van der Waals forces are much weaker than covalent bonds and ionic bonds because they involve intermolecular attractions rather than electron sharing or transfer. Their strength typically ranges from 0.1 to 10 kJ/mol.
- Covalent bonds: 150–1000 kJ/mol (electron sharing).
- Ionic bonds: Strong electrostatic attraction between ions.
- Van der Waals forces: Weak intermolecular forces.
Although weak individually, many Van der Waals interactions together can significantly stabilize molecular structures.
