Intermolecular forces are attractions between separate particles, usually molecules, rather than bonds within a single molecule. Intermolecular forces explain boiling point, melting point, evaporation, solubility, viscosity, and surface tension.
Definition
Intermolecular forces are attractions between separate particles, usually molecules, rather than bonds within a single molecule.
💡 Intuition
These are the attractions between neighboring particles, not the bonds holding each particle together.
🎯 Core Idea
Stronger intermolecular forces usually mean higher boiling points and more resistance to phase change.
Example
Notation
London dispersion forces (LDFs) are weakest, dipole-dipole are intermediate, and hydrogen bonds are strongest among typical IMFs.
🌟 Why It Matters
Intermolecular forces explain boiling point, melting point, evaporation, solubility, viscosity, and surface tension. They connect particle-level chemistry to visible properties of substances.
💭 Hint When Stuck
Identify whether the molecule is nonpolar, polar, or capable of hydrogen bonding. Then match the dominant intermolecular force to that type of particle.
Related Concepts
See Also
🚧 Common Stuck Point
Do not confuse intermolecular forces with covalent or ionic bonds inside a substance.
⚠️ Common Mistakes
- Calling intermolecular forces chemical bonds
- Assuming larger molecules cannot have stronger dispersion forces
- Forgetting that intermolecular forces control physical changes like boiling and melting
Frequently Asked Questions
What is Intermolecular Forces in Chemistry?
Intermolecular forces are attractions between separate particles, usually molecules, rather than bonds within a single molecule.
When do you use Intermolecular Forces?
Identify whether the molecule is nonpolar, polar, or capable of hydrogen bonding. Then match the dominant intermolecular force to that type of particle.
What do students usually get wrong about Intermolecular Forces?
Do not confuse intermolecular forces with covalent or ionic bonds inside a substance.
Prerequisites
Next Steps
How Intermolecular Forces Connects to Other Ideas
To understand intermolecular forces, you should first be comfortable with polarity. Once you have a solid grasp of intermolecular forces, you can move on to hydrogen bonding and state of matter.