London Dispersion Forces Flashcards
1
Q
Why do non-polar moleucles have no permanent separation of charge within bonds?
A
shared electrons pulled equally by two atoms
2
Q
What do noble gases exist as?
A
non-polar particles
3
Q
How are london dispersion forces formed?
A
- electrons behave like mobile clouds of negative charge
- density of cloud may be greater at one moment
- over one region temporary/instantaneous dipole formed
- influences electron distribution in neighbouring atoms
- causes induced dipole weak
- forces of attraction (london forces) occur between opposite ends of two temporary dipoles in molecules
4
Q
london forces are the — form of intermolecular force
A
weakest
5
Q
the strenght of london forces — with moledulcar size Why?
A
increases greater number of electrons within a molecule increases probability of dipole developing
6
Q
trend in melting/boiling points in non-polar molecules
A
- low melting/boiling points
- london forces are only forces that exist between non-polar molecules
- little energy required to break weak london foces and separate molecules from each other
7
Q
hydrogen bonding
A
attraction when a molecule contains a hydrogen covalently bonded to a very electronegative atom (F, N, O)
8
Q
hydrogen bonding effect on boiling point
A
makes boiling point much higher
