Intermolecular Forces
Intermolecular forces act between molecules or ions and must be overcome during a physical change
These forces are collectively known as Van der Waals forces
Types of Forces
Dipole-Dipole
The force of 2 dipole molecules
Hydrogen Bonding
A special case of dipole-dipole bonding that involves a molecule containing H and a very electronegative element (F, O, and N)
Known as a "hydrogen bond", but is actually a very strong dipole-dipole force (10x stronger)
Ion-Dipole
Ion-Induced dipole
An ion is brought close to a non-polar molecule and then electrons from the molecule go to one side of the molecule causing an electron imbalance Molecular Polarity
When the ion is moved away, the polarized non-polar molecule becomes non-polar again
Dipole-Induced dipole
A dipole molecule is brought close to a non-polar molecule and the partially positive or negative side attracts or repels electrons on the non-polar molecule causing an electron imbalance
When the dipole is moved away, the polarized non-polar molecule becomes non-polar again
London Dispersion Forces
Happens when more electrons end up on one atom temporarily and by chance, causing the atom to become a dipole temporarily
LDFs are present in all molecules, but are weak. Force increases as the number of electrons in a molecule increase
---> LDF increases with # of electrons --->