Intermolecular Forces

Question 1

Intermolecular forces

Answer 1

> relatively weak interactions that occur between molecules

> dipole-dipole interactions
London Dispersion Forces

Question 2

Types of intermolecular forces

Answer 2

In order of strength:
>ion-dipole interactions
>hydrogen bonding
>dipole-dipole interactions
>dipole-induced dipole interactions
>London dispersion effect

Question 3

Dipole-dipole interactions

Answer 3

> occurs between polar molecules (i.e. H2O)
includes H+ bonding
maximizes positive-negative interactions and minimizes repulsive positive-positive/negative-negative interactions
1% as strong as covalent or ionic bonding

Question 4

Dipole-dipole attraction

Answer 4

> occurs between polar molecules
positive end of one molecule interacts with close to negative tend of second molecule
in liquid phase, molecules find the best compromise between attraction and repulsion
(If molecules are very far apart, such as low gas pressure, dipole-dipole interactions become negligible)

Question 5

Hydrogen bonding

Answer 5

> strong dipole-dipole interaction involving molecules containing hydrogen bound to a very electronegative atom (with a partial positive charge i.e. H-O, H-N, H-F)

Question 6

London dispersion forces

Answer 6

> instantaneous dipole (polarization of charge) that occurs accidentally know a given atom induces a similar dipole in a neighbouring atom
leads to an interaction IV attraction that is relatively weak and short-lived, but can vary significantly in larger atoms or molecules
happens in ALL molecules (including non-polar ones)
dispersion forces arose from formation of instantaneous dipoles
leads to an inter-atom attraction