Water
Water has both passive and active roles
Passive: things happening simply because of water being there
Active: water is a participant in many biochemical reactions.
Structure/Function Relationship
Oxygen – more electronegative (permanent dipole)
Oxygen has partial negative, and hydrogens have partial positive charge
The dipole of a water molecules influences it’s ability
to:
o Form electrostatic interactions with charged
molecules
o Form hydrogen bonds (including with other
water molecules)
Hydrogen Bonds:
Electrostatic interactions between electronegative
atoms with a hydrogen covalently linked (donor) to
another electronegative atom with a free electron pair
(acceptor)
o For all H – Bonds you’ll have a electronegative
atom (Nitrogen, O) covalently bonded to
Hydrogen. This gives Hydrogen a partial positive charge and then
there is another electronegative atom with a free-floating electron
which has a negative charge. (So, positive Hydrogen and negative
atom attracts, forming H-bonds)
O and N are hydrogen bonders (can serve as both donor and acceptor)
Weaker and longer (double) than covalent
Strength of H-bonds depends on geometry
Water can donate two H-bonds and accept two H-bonds
, Structure/Function Relationship
Permanent dipole in water due to Oxygen being more electronegative
Dipole of water helps it to
o Form electrostatic interactions with charged molecules
o Form H- bonds
Water molecules like to interact with other water molecules.
Properties
Heat of Vaporization: the amount of heat requires to vaporize a liquid at its
boiling temp.
Specific Heat Capacity: the amount of heat required to raise the temp. of a
substance by 1°C
Water has high HoV and SHC since the presence of hydrogen bonds
Most living organisms are isothermic, they need to regulate and maintain
their temp.
Water absorbs all the release of energy in the body without increasing the
body temperature (this is due to the high HoV and SHC)
In ice, water participates in 4 H-bonds with other water molecules.
o This arrangement has lower density (ice floats)
o Ice takes up more volume
Electrostatic Interactions
Favourable to interact with other ions (both + and -ve), since water has a
slight negative charge
Water can interact, and dissolve charged solutes through formation of layers
of hydration
o Salt dissolves quickly in water since, Na+ gets attracted to the -ve side
of the water (negative dipole of O) and Cl- gets attracted with the +ve
side of the water (positive dipole of H)
Water has both passive and active roles
Passive: things happening simply because of water being there
Active: water is a participant in many biochemical reactions.
Structure/Function Relationship
Oxygen – more electronegative (permanent dipole)
Oxygen has partial negative, and hydrogens have partial positive charge
The dipole of a water molecules influences it’s ability
to:
o Form electrostatic interactions with charged
molecules
o Form hydrogen bonds (including with other
water molecules)
Hydrogen Bonds:
Electrostatic interactions between electronegative
atoms with a hydrogen covalently linked (donor) to
another electronegative atom with a free electron pair
(acceptor)
o For all H – Bonds you’ll have a electronegative
atom (Nitrogen, O) covalently bonded to
Hydrogen. This gives Hydrogen a partial positive charge and then
there is another electronegative atom with a free-floating electron
which has a negative charge. (So, positive Hydrogen and negative
atom attracts, forming H-bonds)
O and N are hydrogen bonders (can serve as both donor and acceptor)
Weaker and longer (double) than covalent
Strength of H-bonds depends on geometry
Water can donate two H-bonds and accept two H-bonds
, Structure/Function Relationship
Permanent dipole in water due to Oxygen being more electronegative
Dipole of water helps it to
o Form electrostatic interactions with charged molecules
o Form H- bonds
Water molecules like to interact with other water molecules.
Properties
Heat of Vaporization: the amount of heat requires to vaporize a liquid at its
boiling temp.
Specific Heat Capacity: the amount of heat required to raise the temp. of a
substance by 1°C
Water has high HoV and SHC since the presence of hydrogen bonds
Most living organisms are isothermic, they need to regulate and maintain
their temp.
Water absorbs all the release of energy in the body without increasing the
body temperature (this is due to the high HoV and SHC)
In ice, water participates in 4 H-bonds with other water molecules.
o This arrangement has lower density (ice floats)
o Ice takes up more volume
Electrostatic Interactions
Favourable to interact with other ions (both + and -ve), since water has a
slight negative charge
Water can interact, and dissolve charged solutes through formation of layers
of hydration
o Salt dissolves quickly in water since, Na+ gets attracted to the -ve side
of the water (negative dipole of O) and Cl- gets attracted with the +ve
side of the water (positive dipole of H)
