Properties of Water
*Hydrogen Bonding
*Capillary Action
*pH
Water Molecule Basic Structure
http://programs.northlandcollege.edu/biology/Biology1111/animations/hydrogenbonds.html
View this animation
Surface Tension
The attraction between
water molecules forms a
“skin” on the surface of a
water droplet. This is why
water droplets are curved or
dome-shaped.
Hydrogen Bonding Between Water Molecules
Note that the bond
between the Hydrogen
and Oxygen atoms is a
physical, covalent bond
and is very strong. The
hydrogen bond is a weak
attraction between the
slightly charged oxygen
and hydrogen atoms and
is not a physical bond.
Surface tension is essential for the survival of many plants
and animals that live and hunt at the water’s surface in
lakes, streams and rivers.
Picture above is a water strider, a common freshwater
insect. These insects are predators and eat many insect
larvae including mosquitos.
Detergents/Soaps are surfactants, or substances that
break up the hydrogen bonds between water molecules
so that the water molecules can spread out.
Adhesion and Cohesion
Cohesion: “co” means “like” or
similar.; attraction between two of
the same substances; example is
attraction between two water
molecules.
Adhesion: attraction
between two different
substances: example is
attraction of water
molecule to glass, or the
inside of a xylem tube in a
plant.
Adhesion, Cohesion and Capillary Action
Step 2: Capillary action
• Cohesion: polar
water molecules
tend to stick
together with
hydrogen bonds.
• Adhesion: water
molecules tend
to stick to polar
surfaces.
Glass tube or xylem
Capillary action
• Cohesion and
adhesion cause
water to “crawl”
up narrow tubes.
The narrower the
tube the higher
the same mass of
water can climb.
• Maximum height:
32 feet.
Transpiration: water movement in plants soil to root to leaf to
atmosphere
http://croptechnology.unl.edu/anim
ationOut.cgi?anim_name=transpirat
ion.swf&width=0&height=0
Click to view animation!
Bottom of leaf: stomates (stomata) are tiny pores in the
bottom of a leaf that allows water and gas exchange
with the environment.
Water and pH
-pH stands for potential Hydrogen (H+) ions. The more H+ ions, the more acidic.
-pH is based on water or how a substance reacts with water when dissolved in water.
Dissociation means to split
apart. The OH- or hydroxyl
ions are considered
alkaline or basic with H+ or
hydrogen ions are
considered acidic.
(Increasing alkalinity)
Acids have more H+ ions; Bases (also called alkali) have higher OH- ion concentration.
Li +
H2O ------------------ LiOH
Does lithium (Li) form an acid or base
in water?
Answer)…BASE (note the OH- group)
+ H2 gas
If it weren’t for the hydrogen
bonding between water
molecules…
Life as we know it would NOT
EXIST on this planet…
Here are a few examples:
Water as a solvent and as a regulator of
temperature in your body and the entire
http://programs.northlandcollege.edu/biology/Biology1111/animations/dissolve.html
planet:
View water as a great solvent (DISSOLVER!!)
-
http://www.sumanasinc.com/webcontent/animations/content/propertiesofwater/water.html
-View water’s properties and heat regulation
-http://www.youtube.com/watch?v=BpQ5_uyUmfY&p=8098E1F65E432A4A&playnext=1&index=29
specific heat capacity