When we think of bonding, we often imagine two atoms sharing electrons to form a covalent bond or one atom losing electrons to another to form an ionic bond. But there is another type of bonding that holds molecules together, and that is Van der Waals bonding.

What is Van der Waals Bonding?

Van der Waals bonding is a type of weak intermolecular force that exists between atoms and molecules. Unlike covalent and ionic bonds, Van der Waals bonding does not involve the sharing or transfer of electrons. Instead, it arises from the interaction between temporary dipoles that occur when electrons are not evenly distributed in a molecule.

These temporary dipoles create a fluctuating electrical field that induces similar dipoles in neighboring molecules. The resulting attraction between the dipoles is known as a Van der Waals force or Van der Waals interaction.

Types of Van der Waals Bonding

There are two types of Van der Waals bonding: London dispersion forces and dipole-dipole interactions.

London Dispersion Forces

London dispersion forces are the weakest type of Van der Waals bonding. They arise from the temporary dipoles that occur in all molecules due to the random movement of electrons. These temporary dipoles are constantly changing, but at any given moment, they create a small attraction between neighboring molecules.

London dispersion forces are responsible for the attraction between nonpolar molecules such as noble gases and hydrocarbons. Although weak, they become significant when there are many molecules present, such as in a liquid or solid.

Dipole-Dipole Interactions

Dipole-dipole interactions occur between polar molecules that have a permanent dipole moment. A dipole moment is created when there is an unequal distribution of electrons in a molecule, resulting in a partial positive charge on one end and a partial negative charge on the other.

In a polar molecule, the positive end of one molecule is attracted to the negative end of a neighboring molecule, creating a dipole-dipole interaction. This type of Van der Waals bonding is stronger than London dispersion forces but weaker than covalent or ionic bonds.

Examples of Van der Waals Bonding

Van der Waals bonding is present in many everyday substances. Here are some examples:

Water

Water is a polar molecule with a dipole moment. The partial positive charge on the hydrogen atoms is attracted to the partial negative charge on the oxygen atom of neighboring water molecules, creating dipole-dipole interactions. London dispersion forces also contribute to the overall attraction between water molecules.

Helium

Helium is a noble gas with a full valence shell and no permanent dipole moment. However, London dispersion forces still exist between helium atoms due to the temporary dipoles created by the movement of electrons.

Graphite

Graphite is a form of carbon that consists of layers of hexagonal rings. The layers are held together by Van der Waals bonding, specifically London dispersion forces. This weak bonding allows the layers to slide past each other, making graphite an excellent lubricant.

Importance of Van der Waals Bonding

Although Van der Waals bonding is weak compared to covalent and ionic bonding, it plays a crucial role in the properties of many substances. Without Van der Waals bonding, many substances would not exist in their current forms or have the same properties.

For example, the Van der Waals bonding between water molecules gives water its high boiling point and surface tension. The Van der Waals bonding between molecules in a solid gives it its shape and rigidity.

Conclusion

Van der Waals bonding is a type of weak intermolecular force that arises from the interaction between temporary dipoles in molecules. It exists in many everyday substances and plays a crucial role in their properties. Understanding Van der Waals bonding is essential for understanding the behavior of matter at the molecular level.

Related video of Van der Waals Bonding: The Force That Holds Molecules Together