4. Water is the material cause of all things
(Thales, 624 – 546 BC) 4/5/2015 4
5. COMPOSITION
Water is composed of hydrogen and oxygen.
Two volumes of hydrogen combine with one
volume of oxygen
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6. STRUCTURE
An atom of oxygen is bound
covalently to two atoms of
hydrogen.
Tetrahedral angle of 104.5°
between the two O–H bonds.
a) Oxygen atom has two lone
electron pairs Four H bonds
b) Hydrogen bonds through its
two H atoms to two other
water molecules (forming
network)
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9. POLARITY
Magnitude of an atom’s partial charge
a measure of its polarity
Electrically polarized,
Dipole moment
6 X 10-30C m gas phase.
8 X 10-30 C m) in liquid and ice
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11. SOLVENT PROPERTIES
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Universal solvent- related to polarity
Slight negative and positive charge- Makes
compounds to dissociate
Sphere of Hydration
Hydrophilic Hydrophobic
13. THERMAL PROPERTIES
4/5/2015 13
Specific Heat
• Highest
(1 calorie)
• Long time to
heat and cool
Heat of
Vaporization
• High (586 cal)
• Absorbs heat
• Evaporation
Boiling and
Freezing
• 100oC (212oF)
and freezes at
0oC(32o F)
Water density
• 4oC (36o F)–
Highly dense
• Less dense
0oC(32o F)
• Ice floats in
water
17. SURFACE PROPERTIES
4/5/2015 17
SurfaceTension
Second highest
Surface tension
Squeezes the liquid
into the shape with
the smallest
possible surface
area.
Cohesion
Creates a high
surface tension at
the surface of the
water.
Adhesion
Wettability
Capillary action
18. 4/5/2015 18
HAVE YOU EVER WONDERED?
F Persson & B Halle, JACS 135, 8735–8748 (2013).S Kaieda & B Halle, J Phys Chem B,
19. 4/5/2015 19
WATER AND PROTEINS
StructuralStability
Proteinbinding
Function
J Qvist, M Davidovic,
D Hamelberg & B
Halle, PNAS 105,
6296–6301 (2008).
PDB ID code 2BOP
