Induced Dipoles

Definition

Induced dipoles are temporary, instantaneous dipole moments that arise in molecules or atoms when they are in the presence of an external electric field or another polar molecule. This occurs due to the slight separation of positive and negative charges within the molecule, creating a temporary dipole.

5 Must Know Facts For Your Next Test

1. Induced dipoles are temporary and can arise in both polar and non-polar molecules or atoms.
2. The strength of an induced dipole is directly proportional to the strength of the external electric field or the polarity of the neighboring molecule.
3. Larger, more polarizable molecules or atoms tend to have stronger induced dipoles due to their greater ability to have their electron distribution distorted.
4. Induced dipoles contribute to the cohesion of matter through van der Waals forces, which are important in various physical and chemical processes.
5. London dispersion forces, a type of van der Waals force, arise from the temporary, instantaneous dipoles created in non-polar molecules or atoms.

Review Questions

• Explain how the presence of an external electric field or a polar molecule can lead to the formation of induced dipoles.
  • When a molecule or atom is placed in the presence of an external electric field or a polar molecule, the uneven distribution of electrons within the molecule can be distorted. This distortion creates a temporary separation of positive and negative charges, resulting in the formation of an induced dipole. The strength of the induced dipole is directly proportional to the strength of the external electric field or the polarity of the neighboring molecule. Larger, more polarizable molecules or atoms tend to have stronger induced dipoles due to their greater ability to have their electron distribution distorted.
• Describe the relationship between induced dipoles and van der Waals forces, and how they contribute to the cohesion of matter.
  • Induced dipoles are the underlying cause of van der Waals forces, which are attractive forces that arise between temporarily induced dipoles in molecules or atoms. These van der Waals forces, including London dispersion forces, contribute to the cohesion of matter by holding molecules or atoms together. The strength of the van der Waals forces, and thus the cohesion of the matter, is directly related to the strength of the induced dipoles present. Larger, more polarizable molecules or atoms tend to have stronger induced dipoles and, consequently, stronger van der Waals forces, leading to greater cohesion of the material.
• Analyze the role of induced dipoles in various physical and chemical processes, and explain how an understanding of this concept can be applied to predict or understand these processes.
  • Induced dipoles play a crucial role in a wide range of physical and chemical processes. Understanding the concept of induced dipoles and their relationship to van der Waals forces can help predict and explain various phenomena, such as the solubility of non-polar molecules in polar solvents, the surface tension of liquids, the boiling and melting points of substances, and the adsorption of molecules on surfaces. By considering the polarizability of molecules and the strength of the induced dipoles, one can anticipate the relative strength of the van der Waals forces and, consequently, the behavior of the system. This knowledge can be applied to optimize chemical reactions, design effective separation techniques, and understand the physical properties of materials, among other applications.

Related terms

Van der Waals Forces: Attractive forces that arise between temporarily induced dipoles in molecules or atoms, contributing to the cohesion of matter.

Polarizability:

The ability of a molecule or atom to have its electron distribution distorted by an external electric field, leading to the formation of induced dipoles.

London Dispersion Forces:

A type of van der Waals force that arises from the temporary, instantaneous dipoles created in non-polar molecules or atoms.