Chapter 1: 1.7 Intermolecular Forces Flashcards
What are intermolecular forces?
Forces which occur between molecules
* Affects many physical properties such as boiling and melting point
What are examples of intermolecular forces?
- Ionic forces
- Hydrogen bonding
- Dipole-dipole interactions
- Van der Waals forces
Describe:
Van der Waals Forces
Weakest intermolecular force that occurs between non-polar molecules
* Results of the interaction of transient and/or induced dipoles
True or False:
Larger molecules or atoms experience the same amount of Van der Waals forces as small molecules
False, they experience more pronounced Van der Waals forces
What are Van der Waals forces also known as?
London Dispersion Forces
Describe:
Dipole-Dipole Interactions
Moderate (medium) intermolecular forces and occurs between polar molecules (i.e. those with a permanent dipole)
Describe:
Hydrogen Bonding
Strongest intermolecular force that occurs and are a special kind of dipole-dipole interaction
Where do hydrogen bonding occur?
Occurs between a hydrogen-bond donor (OH, NH, FH) and a hydrogen bond acceptor (O, N, F with one or more lone pairs)
State:
The relative strengths of intermolecular forces
Hydrogen bonding > Dipole-dipole interactions > London dispersion forces
True or False:
Intermolecular forces dictate melting and boiling points
True
Melting and boiling involve —– ——- which means the bonds between molecules need to be ——
- Phase changes
- Broken
Give examples of phase changes
- Solid to liquid
- Liquid to gas
Stronger intermolecular forces equals…
Higher melting/boiling points
How do you determine the relative boiling point if two molecules are similar?
- Consider the number or atoms/electrons
- Consider the molecular shape
