Intermolecular Forces
Intermolecular forces are the forces of attraction between molecules. They determine the physical properties of substances, such as boiling
points, melting points, and solubility. There are three main types of intermolecular forces:
1. London Dispersion Forces (Van der Waals Forces)
Occur in all molecules, whether polar or non-polar.
Caused by temporary dipoles due to the random movement of electrons.
Strength increases with molecular size and surface area.
Weakest type of intermolecular force.
2. Permanent Dipole-Dipole Forces
Occur between polar molecules with permanent dipoles.
Arise from the electrostatic attraction between partially positive (δ+\delta^+) and partially negative (δ−\delta^-) ends of polar molecules.
Stronger than London dispersion forces but weaker than hydrogen bonding.
3. Hydrogen Bonding
A special, strong type of dipole-dipole interaction.
Occurs when hydrogen is bonded to highly electronegative atoms like fluorine (F), oxygen (O), or nitrogen (N).
The hydrogen atom acts as a bridge between two electronegative atoms, creating a strong attraction.
Strongest type of intermolecular force.
Effect on Physical Properties
Intermolecular forces are the forces of attraction between molecules. They determine the physical properties of substances, such as boiling
points, melting points, and solubility. There are three main types of intermolecular forces:
1. London Dispersion Forces (Van der Waals Forces)
Occur in all molecules, whether polar or non-polar.
Caused by temporary dipoles due to the random movement of electrons.
Strength increases with molecular size and surface area.
Weakest type of intermolecular force.
2. Permanent Dipole-Dipole Forces
Occur between polar molecules with permanent dipoles.
Arise from the electrostatic attraction between partially positive (δ+\delta^+) and partially negative (δ−\delta^-) ends of polar molecules.
Stronger than London dispersion forces but weaker than hydrogen bonding.
3. Hydrogen Bonding
A special, strong type of dipole-dipole interaction.
Occurs when hydrogen is bonded to highly electronegative atoms like fluorine (F), oxygen (O), or nitrogen (N).
The hydrogen atom acts as a bridge between two electronegative atoms, creating a strong attraction.
Strongest type of intermolecular force.
Effect on Physical Properties
