Induced Dipole vs. Permanent Dipole

Attribute	Induced Dipole	Permanent Dipole
Polarity	Temporary polarity induced by an external electric field	Permanent polarity due to an uneven distribution of charge
Origin	Occurs in nonpolar molecules when they are influenced by a polar molecule or an external electric field	Occurs in polar molecules due to an uneven distribution of electron density
Strength	Relatively weaker compared to permanent dipoles	Relatively stronger due to a permanent charge separation
Direction	Induced dipole moment aligns with the direction of the external electric field	Permanent dipole moment has a fixed direction within the molecule
Interaction	Induced dipole interacts with other induced or permanent dipoles	Permanent dipole interacts with other permanent dipoles or ions
Examples	Induced dipole-induced dipole (London dispersion forces)	Water (H2O), ammonia (NH3), hydrogen chloride (HCl)

Introduction

In the world of chemistry, dipole moments play a crucial role in understanding the behavior of molecules. Dipole moments arise due to the separation of positive and negative charges within a molecule. There are two types of dipole moments: induced dipole and permanent dipole. While both types involve the separation of charges, they differ in their origin, strength, and behavior. In this article, we will explore the attributes of induced dipole and permanent dipole, shedding light on their similarities and differences.

Induced Dipole

An induced dipole occurs when a molecule that is normally nonpolar experiences a temporary shift in electron density, resulting in a temporary dipole moment. This phenomenon arises due to the presence of an external electric field or the proximity of another polar molecule. When a nonpolar molecule is exposed to an electric field, the electrons within the molecule are displaced, causing a temporary separation of charges. This separation creates a positive and negative end, resulting in an induced dipole moment.

Induced dipoles are typically weaker than permanent dipoles and are highly dependent on the strength of the external electric field or the proximity of the polar molecule. Once the external influence is removed, the induced dipole moment disappears, and the molecule returns to its nonpolar state. This temporary nature of induced dipoles makes them highly dynamic and responsive to changes in the environment.

Induced dipole moments are crucial in various chemical processes, such as London dispersion forces. These forces, also known as van der Waals forces, arise due to the temporary dipoles induced in nonpolar molecules. London dispersion forces play a significant role in intermolecular interactions, determining the boiling points, melting points, and physical properties of substances.

Permanent Dipole

A permanent dipole, as the name suggests, exists in molecules that have a permanent separation of charges. Unlike induced dipoles, permanent dipoles arise due to differences in electronegativity between atoms within a molecule. Electronegativity is a measure of an atom's ability to attract electrons towards itself in a chemical bond. When atoms with different electronegativities are bonded together, the electrons are not shared equally, resulting in a permanent dipole moment.

Permanent dipoles are relatively stronger than induced dipoles and do not rely on external factors to exist. They are a fundamental characteristic of polar molecules and contribute significantly to their chemical behavior. Permanent dipole moments are responsible for various intermolecular forces, such as dipole-dipole interactions and hydrogen bonding.

Dipole-dipole interactions occur between polar molecules and are stronger than London dispersion forces. These interactions play a crucial role in determining the physical and chemical properties of substances, such as solubility, boiling points, and melting points. Hydrogen bonding, a specific type of dipole-dipole interaction, is particularly important in biological systems, influencing the structure and properties of proteins, DNA, and other biomolecules.

Comparison

Now that we have explored the attributes of induced dipole and permanent dipole, let's compare them in terms of their origin, strength, and behavior.

Origin

Induced dipoles arise due to the presence of an external electric field or the proximity of a polar molecule. They are temporary and disappear once the external influence is removed. On the other hand, permanent dipoles originate from differences in electronegativity between atoms within a molecule. They are inherent to polar molecules and do not rely on external factors.

Strength

Induced dipoles are generally weaker than permanent dipoles. The strength of an induced dipole moment depends on the strength of the external electric field or the proximity of the polar molecule. In contrast, permanent dipoles have a fixed strength determined by the electronegativity difference between atoms within the molecule.

Behavior

Induced dipoles are highly dynamic and responsive to changes in the environment. They can quickly form and disappear as the external conditions change. On the other hand, permanent dipoles are stable and do not change unless the chemical structure of the molecule is altered.

Intermolecular Interactions

Both induced dipoles and permanent dipoles contribute to intermolecular interactions. Induced dipoles are responsible for London dispersion forces, which are present in all molecules to some extent. Permanent dipoles, on the other hand, give rise to dipole-dipole interactions and hydrogen bonding, which are stronger than London dispersion forces.

Chemical Properties

The presence of induced or permanent dipoles significantly influences the chemical properties of substances. Induced dipoles contribute to the physical properties of nonpolar molecules, such as their boiling points and melting points. Permanent dipoles, on the other hand, play a crucial role in determining the solubility, reactivity, and behavior of polar molecules.

Conclusion

In summary, induced dipole and permanent dipole are two types of dipole moments that arise due to different factors and exhibit distinct characteristics. Induced dipoles are temporary and rely on external influences, while permanent dipoles are inherent to polar molecules. Induced dipoles are weaker and more dynamic, while permanent dipoles are stronger and stable. Both types of dipoles contribute to intermolecular interactions and significantly impact the chemical properties of substances. Understanding the attributes of induced dipole and permanent dipole is essential in comprehending the behavior of molecules and their interactions in various chemical processes.