(U1) Intermolecular Forces Flashcards
1
Q
What does intermolecular mean?
A
Between neighbouring molecules
2
Q
What are Van Der Waals forces? (3)
A
- attraction between instantaneous
- and induced dipoles
- on neighbouring molecules
3
Q
What is the effect of molecule size on Van Der Waals?
What does this cause?
A
- Increased size of forces
- strength increases —> m.p. And b.p. Increase
4
Q
What is permanent dipole-dipole attraction? (4)
A
- attraction between the positive end (δ+)
- of the permanent dipole on a molecule
- with the negative end (δ-)
- of the permanent dipole of a neighbouring molecule
5
Q
What is a hydrogen bond? (4)
A
- the attraction between a lone pair of electrons
- of a very electronegative atom on a molecule
- and a hydrogen on a neighbouring molecule
- in which the hydrogen is covalently bonded to a very electronegative atom
6
Q
Name 3 very electronegative atoms
A
Nitrogen, Oxygen and Fluorine
7
Q
Between:
- hydrogen bonds,
- Van Der Waals forces and
- dipole-dipole forces
Which is strongest?
A
Hydrogen bonds
8
Q
Why do Van Der Waals forces occur in all molecules?
A
All molecules have electrons
9
Q
When is a molecule said to have a dipole?
A
- When it has a δ- and a δ+ end
- due to one atom being more electronegative than the other
