Chapter 6: Biochemistry
Properties of Water
Polar Covalent Bonds

Pair of electrons not __________ equally by atoms

Water =
o
Oxygen has _________________ attraction for the shared electrons than hydrogen
o
Therefore, oxygen has higher ______________________

2 hydrogens (H) in a water molecule form an _______________

Water molecule is ____________

o
Oxygen end is ____________
o
Hydrogen end is ___________
This leads to many interesting properties of water….
Polar
Nonpolar
Hydrogen Bonds

Positive H end in 1 water molecule is attracted to the ____________ end in the other

Can occur wherever an ____________ exists in a larger molecule

___________ bonds
Water and Its Importance

Why are we studying water?

Water makes up __________ of most living organisms
The Chemistry of Water

Water molecules form _____________ with each other
- creates a sticky molecule
Cohesion & Adhesion

H bonding between water molecules is ___________________
o

Water is ____________

Surface tension

Drinking straw
H bonding between water and other substances is __________________
o
o
Meniscus
o
Water climbing up a paper towel
How does water get to the top of a tree?
Water is the _______________ of life
•
Polarity makes H2O a good
polar H2O molecules surround:
________________ dissolve ________________ creating __________________
Draw what happens:
Do you dissolve in water?
•
Hydrophilic
polar or non-polar?
Or don’t you?
•
Hydrophobic
polar or non-polar?
The Special Case of Ice…
•
Most (all?) substances are more dense when they are solid, but
Not water…
•
H bonds form ______________________
Why is “ice floats” important?
•
surface ice ___________________ water below
allowing life to survive the winter
if ice sank…
- in summer, _________________________________________________________
seasonal _______________________ of lakes
Specific Heat
•
H2O ____________ changes in temperature
takes a lot to cool it down
•
H2O moderates temperatures on Earth