3.1 Intermolecular Forces

London dispersion forces are a result of:

Coulombic interactions between temporary, fluctuating dipoles

London dispersion forces are often the ________ between large molecules

Strongest net intermolecular force

Dispersion forces increase with:

Increasing contact area between molecules and increasing polarizability of molecules

Polarizability of a molecule increaes with:

Increasing number of electrons in the molecule and increasing size of electron cloud

Polarizability is enhanced by the presence of:

Pi bonding

The dipole moment of a polar molecule leads to:

Additional interactions with other chemical species

Dipole-induced dipole interactions are present between:

A polar and nonpolar molecule

Dipole-induced dipole interactions are always:

Attractive

The strength of dipole-induced dipole interactions increases with:

Magnitude of dipole of the polar molecule and polarizability of nonpolar molecule

Dipole-dipole interactions are present between:

Polar molecules

The strength of dipole-dipole interactions depends on:

Magnitudes of dipoles and their relative orientation

Interactions between polar molecules are typically greater/weaker than those between nonpolar molecules of comparable size

Greater

Why are interactions between polar molecules typically greater than those between nonpolar molecules of comparable size?

Dipole-dipole interactions act in addition to London dispersion forces

Ion-dipole forces of attraction are present between:

Ions and polar molecules

Ion-dipole forces tend to be stronger/weaker than dipole-dipole forces

Stronger

The relative strength and orientation dependence of dipole-dipole and ion-dipole forces can be understood qualitatively by:

Considering the sign of the partial charges responsible for the molecular dipole moment and how these partial charges interact with an ion or adjacent dipole

A strong type of intermolecular interaction that exists when hydrogen atoms are covalently bonded to the highly electronegative atoms (N,O,F) are attached to te negative end of a dipole formed by the electronegative atom (N,O,F) in a different molecule, or a different part of the same molecule

Hydrogen bonding

In large biomolecules, noncovalent interactions may occur between:

Different molecules or different regions of the same large biomolecule