Hydrogen BondingSWBAT: Draw hydrogen bonds between two molecules

Definition Hydrogen Bond A hydrogen bond is an electromagnetic attraction -

not a true bond! Hydogen must be directly bonded to a small atom

with high EN (N, O, F) Can form with another molecule (intermolecular) or

another part of the same molecule (intramolecular). The hydrogen has a partial δ+ charge and the oxygen

has a partial δ- charge from being covalently bonded to an electronegative atom

Symbol Covalent bond: solid line H-bond: dotted line

Intermolecular H Bonding Hydrogen bonding between two

molecules – from the attraction of the dipoles

Intramolecular H-bonding DNA Hydrogen bonding within its own molecule

– from the attraction of the dipoles

Intra…..3D- Structure of Proteins

Intra…..3D- Structure of Proteins

Hydrogen Bonding

Important H-bonds do not have to involve water

molecules! All it needs is a δ+ H which can come from

any molecule: SH2, C-OH, COOH, DNA, proteins….

And a δ- element as a neighbor (usually its O, S, N, P or the Halogen group)

Beryllium Chloride (tri-hydride) BeCl2 •3H2O

Organic molecules and H-bonds Draw dipole and partial charges of the

following functional groups: don’t forget the unpaired Valence e- of Oxygen

COH Alcohol CHO Aldehyde CO Ketone COOH Acid

H-Bond Drawing guide Oppose each δ+ and δ- with one H2O Show the δ+ and δ- and net dipole of

each water molecule Draw H-bonds as dotted linesPractice: CH3COH •3H2O CH3CH2 COOH •4H2O CH2O •2H2O