What is the Difference Between Interatomic and Intermolecular Forces

The main difference between interatomic and intermolecular forces is that interatomic forces are forces that exist between individual atoms within a molecule or a solid material, whereas intermolecular forces are forces that exist between molecules.

Interatomic forces and intermolecular forces are both types of forces that exist between particles. There are several differences between them.

Key Areas Covered

1. What are Interatomic Forces
      – Definition, Types, Features
2. What are Intermolecular Forces
      – Definition, Types, Features 
3. Similarities – Interatomic and Intermolecular Forces
      – Outline of Common Features
4. Difference Between Interatomic and Intermolecular Forces
      – Comparison of Key Differences

Key Terms

Interatomic Forces, Intermolecular Forces

What is an Interatomic Force

Interatomic forces are the forces that exist between individual atoms within a molecule or a solid material. These interatomic forces determine the properties, behavior, and stability of atoms and molecules. There are several types of interatomic forces, each arising from different interactions between charged particles within atoms.

1. Ionic Forces

These types of forces occur between ions with opposite charges. In ionic compounds, the transfer of electrons from one atom to another creates positively charged cations and negatively charged anions. The electrostatic attraction between these oppositely charged ions generates strong ionic forces, leading to the formation of a lattice structure in solids.

2. Covalent Bonds

Covalent bonds involve the sharing of electrons between atoms. Atoms combine to form molecules by sharing one or more pairs of electrons, resulting in the formation of stable molecular structures. The strength of the covalent bond is determined by factors such as the number of shared electrons, bond length, and bond angles.

3. Metallic Bonds

Metallic bonding occurs in metals where the valence electrons are not localized around the individual atoms but instead form a pool of delocalized electrons. These mobile electrons move throughout the metallic lattice creating a bonding force that holds metal atoms together.

4. Van Der Waals Forces

Van der Waals forces encompass several types of interatomic forces. These forces arise from temporary or induced dipoles. These forces include dipole-dipole interactions, London dispersion forces, and hydrogen bonding.

Interatomic forces have a significant impact on the physical and chemical properties of materials. They affect the boiling point, melting point, solubility, and mechanical properties.

 What are Intermolecular Forces

Intermolecular forces are the forces of attraction or repulsion that exist between molecules or particles that are not bonded within a molecule. There are several types of intermolecular forces, each arising from different interactions between molecules or particles.

1. Dipole-Dipole Interactions

Dipole-dipole interactions occur between polar molecules. In polar molecules such as water, the asymmetrical distribution of electron density results in a permanent dipole moment. The positive end of one polar molecule is attracted to the negative end of another, leading to dipole-dipole interactions. These forces are stronger than other intermolecular forces.

2. London Dispersion Forces

London dispersion forces, also known as van der Waals forces, are the weakest intermolecular forces. They arise as a result of the temporary fluctuations in the electron distributions within atoms or non-polar molecules. These fluctuations create instantaneous or induced dipoles resulting in attractive forces between neighboring atoms or molecules. These are weak forces.

3. Hydrogen Bonding

Hydrogen bonding is a specific type of dipole-dipole interaction that occurs when hydrogen is bonded to a highly electronegative atom like oxygen, nitrogen, or fluorine.

4. Ion-Dipole Interactions

Ion-dipole interactions occur between an ion and the partial charges of the polar molecules.

The strength of these intermolecular forces determines the physical properties and behavior of the substances. They affect the melting point, boiling point, vapor pressure, solubility, and phase behavior of substances.

Similarities Between Interatomic and Intermolecular Forces

• Interatomic and intermolecular forces have an electrostatic nature.
• Both influence the properties of substances.

Difference Between Interatomic and Intermolecular Forces

Definition

Interatomic forces are forces that exist between individual atoms within a molecule or a solid material, whereas intermolecular forces are forces that exist between molecules.

Types

Types of interatomic forces include metallic bonds, covalent bonds, ionic forces and Van der Waals forces, while types of intermolecular forces include dipole-dipole interactions, London dispersion forces, and hydrogen bonding.

Strength of the Forces

Interatomic forces are typically stronger than intermolecular forces.

Conclusion

The main difference between interatomic and intermolecular forces is that interatomic forces are forces that exist between individual atoms within a molecule or a solid material, whereas intermolecular forces are forces that exist between molecules.

Reference:

1. “Different Types Of Intermolecular Forces.” Byju’s.
2. “Interatomic Forces.” Warren County Schools.

Image Courtesy:

1. “Liquid water hydrogen bond” By I, Splette (CC BY-SA 3.0) via Commons Wikimedia
2. “Interatomic interaction potential” By Taojiang12345 – Own work (CC BY-SA 4.0) via Commons Wikimedia