Forces between molecules - hydrogen bonding Flashcards
1
Q
what type of force is hydrogen bonding?
A
a special type of the dipole-dipole force (not really a true chemical bond)
2
Q
strength?
A
strongest intermolecular force
3
Q
when can a hydrogen bond exist?
A
when a hydrogen atom is present in the molecule AND it is bonded to a N, O or F atom in the same molecule
4
Q
which dipole is the hydrogen atom always?
A
the positive dipole (N, O or F always negative dipole)
5
Q
what makes a hydrogen bond so strong?
A
- polar bond between H and N/O/F leaves H nucleus exposed as H only has one electron
- strong attraction from lone pair of N/O/F of one molecule to exposed H nucleus of another molecule
6
Q
hydrogen bond drawing example
A
7
Q
what 3 things should you always show in a drawing of hydrogen bonds?
A
- lone pairs
- charges (d+ and d-)
- dotted line between lone pair and H on different molecules
8
Q
order of strengths of intermolecular forces
A
H-bonding > permanent dipole-dipole > van der Waals’
