The Extraordinary
Properties of Water
Water
• A water molecule (H2O), is
made up of three atoms --one oxygen and two hydrogen.
H
H
O
Water is Polar
• In each water molecule, the oxygen
atom attracts more than its "fair
share" of electrons
• The oxygen end “acts” negative
• The hydrogen end “acts” positive
• Causes the water to be POLAR
• However, Water is neutral (equal
number of e- and p+) --- Zero Net
Charge
Hydrogen Bonds Exist
Between Water Molecules
• Formed between a highly
Electronegative atom of
a polar molecule and a
Hydrogen
• One hydrogen bond is
weak , but many
hydrogen bonds are
strong
Interaction Between Water
Molecules
Negative Oxygen end of one water molecule is
attracted to the Positive Hydrogen end of another
water molecule to form a HYDROGEN BOND
What are
the
Properties
of Water?
Properties of Water
• At sea level, pure water boils at
100 °C and freezes at 0 °C.
• The boiling temperature of water
decreases at higher elevations
(lower atmospheric pressure).
• For this reason, an egg will take
longer to boil at higher altitudes
Properties of Water
• Cohesion
Cohesion
• Attraction between particles of the
same substance ( why water is
attracted to itself)
• Results in Surface tension (a measure
of the strength of water’s surface)
• Produces a surface film on water that
allows insects to walk on the surface
of water
Cohesion …
Helps insects walk across
water
Properties of Water
• Cohesion
• Adhesion
Adhesion
• Attraction between two different
substances.
• Water will make hydrogen bonds with other
surfaces such as glass, soil, plant tissues,
and cotton.
• Capillary action-water molecules will “tow”
each other along when in a thin glass tube.
• Example: transpiration process which plants
and trees remove water from the soil, and
paper towels soak up water.
Adhesion Causes Capillary
Action
Which gives water the
ability to “climb”
structures
Adhesion Also Causes
Water to …
Form spheres &
hold onto plant
leaves
Attach to a
silken spider
web
Why does water form?
In a water molecule two
hydrogen atoms form single
covalent bonds with an oxygen
atom.
The bonds are formed to
create a “stable” molecule.
Oxygen needs 2
more electrons to be
stable.
Hydrogen needs 1
more electron to be
stable.
*Gives water more
structure than other
liquids*
Water Activity
Sticky Molecule Article
Directions:
1. Color
1. All oxygen RED
2. All hydrogen Blue
3. Two Electrons Yellow
2. Cut all circles
3. Glue
1. Oxygen nucleus over center of O
2. Hydrogen nuclei over H
4. Glue oxygen and Hydrogen to paper
5. Place electrons ask teacher
confirmation.
6. Glue Electrons
7. Write Article by answering questions
Water Activity
Sticky Molecule 1.Article
Name the elements found in the
water molecule. What is the ratio of
hydrogen to oxygen.
2. How does one molecule of water
form? What is the name of the
bond (label it in your picture)
3. Describe a polar molecule. Also
label this in your picture!
4. How do two molecules of water
stick together? What is the name of
the bond and property?
5. Describe what is happening when
water flows down a piece of wet
yarn.
Properties of Water
• Cohesion
• Adhesion
• Universal Solvent
Water ……a.k.a the Universal Solvent
Water is the solvent of Life!
- Because of the polarity water is able
to dissolve the many substances.
Solute – substance dissolved in a
solvent to form a solution
Solvent – fluid that dissolves solutes
Solving Dissolving Lab!
Solubility Lab! – ws#6
Solubility Lab! – ws#6
Solubility Lab! – ws#6
Solubility Lab! – ws#6
Properties of Water
• Cohesion
• Adhesion
• High Specific Heat
High Specific Heat
• Amount of heat needed to raise or
lower 1g of a substance 1° C.
• Water resists temperature change,
both for heating and cooling.
• Water can absorb or release large
amounts of heat energy with little
change in actual temperature.
Water holds onto Heat
and won’t let it go!
•
•
The amount of heat that a substance
can “hold” is called Heat Capacity.
Three-fourths of the earth is covered
by water. The water serves as a large
heat “sink” (or bank) responsible
for:
1. Prevention of temperature fluctuations that are outside the
range suitable for life.
2. Coastal (Beach) areas having a mild climate
3. A more stable marine (water) environment
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Properties of Water
• Cohesion
• Adhesion
• High Specific Heat
• High Heat of Vaporization
Properties of Water
• Cohesion
• Adhesion
• High Specific Heat
• High Heat of Vaporization
• Less Dense as a Solid
Water is Less Dense as a
Solid
• Ice is less dense as a solid than as a
liquid (ice floats)
• Liquid water has hydrogen bonds that
are constantly being broken and
reformed.
• Frozen water forms a crystal-like
lattice whereby molecules are set at
fixed distances.
Water is Less Dense as a
Solid
•Which is ice and which is water?
Water is Less Dense as a
Solid
Water
Ice
Only water is found _____________
as a SOLID, LIQUID, and GAS on
Earth!
While all elements
will change states,
only some compounds
will.
Water changes state
within a very narrow
range, allowing it to
snow, rain, and
evaporate… all on the
same day!
37
Ice is less dense
than liquid water!
Solids are usually more
dense than liquids because
their molecules are closer
together. Liquids are more
dense than gases… but not
for water. Water forms a
___________________
structure which makes ice
(solid water) less dense than
liquid water.
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Solid
Organize
d
Liquid
Gas
Disorganize
d
Free Floating
Water “grows”
when freezing:
1. This causes potholes on
road and weathering of
rocks.
2. It prevents water from freezing from the bottom up.
Ice forms on the surface first—the freezing of the
water releases heat to the water below creating
insulation. This makes transitions between seasons
less abrupt.
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