2.6 Hydrogen Bonding

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2.6 Hydrogen Bonding

• 2.6.1. Hydrogen Bonds

LO I understand what is meant by hydrogen
bonding.
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The bonding in hydrogen fluoride is much stronger
than can be accounted for by
attractions alone.
polar-polar
hydrogen

• This is bonding.

Increasing strength of bonds/forces
van der Waals
ionic
hydrogen
polar-polar
covalent
LO I understand what is meant by hydrogen
bonding.
3
Hydrogen bonds form in molecules where a hydrogen
atom is bonded to a ,
or . atom.
nitrogen
oxygen
fluorine
H2O, CH3OH (methanol)
NH3, CH3NH2 (methylamine)
hydrogen
Hydrogen bonds form between a
atom in one molecule and a nitrogen, oxygen or
fluorine atom in a neighbouring molecule.
LO I understand what is meant by hydrogen
bonding.
4
2.6.2. Boiling Points

• LO I understand the pattern in the boiling
  points of the group 7 hydrides.

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Boiling points of the group 7 hydrides vs period
number.
Extrapolating the graph from HCl downwards would
give a boiling point of C for HF.
-100
Hydrogen
bonding has increased the
boiling point of HF by over 100C.
LO I understand the pattern in the boiling
points of the group 7 hydrides.
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2.6.3. H-Bonds and Viscosity

• LO I understand the affect H-bonds have on
  viscosity.

LO I understand the affect H-bonds have on
viscosity.
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propan-2-ol
propanone
H-bonds present
H-bonds not present

• Propan-2-ol is viscous than propanone
  due to the H-bonds between the molecules.

more
The H-bonds between the propan-2-ol molecules
prevent them from each
other easily.
slipping past
LO I understand the affect H-bonds have on
viscosity.