The Properties
of Water
Adapted from Biology Junction
Water
A water molecule (H2O), is made
up of three atoms.
one oxygen and two hydrogen
H
O
H
Water is Polar
Water is an overall neutral
molecule because it has an
equal number of electrons
and protons.
The oxygen end “acts”
negative
The hydrogen end “acts”
positive
This is why water is
described as POLAR
Interaction Between Water Molecules
The negative oxygen end of one water molecule
is attracted to the positive hydrogen end of
another water molecule.
This is why water molecules are attracted to
each other.
This is called
COHESION.
Cohesion 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.
In summary…
A water molecule has a positive and negative
end (polar), so… water molecules are attracted
to water molecules (cohesion) and… this
creates surface tension.
Jesus Christ Lizard
Adhesion is the attraction
between two different
substances.
Water molecules
will make bonds
with other
surfaces such as
glass, soil, plant
tissues, and
cotton.
Adhesion causes Capillary Action
Capillary Action occurs when water
molecules “tow” each other along
when in a thin tube.
Transpiration is a form of capillary
action where plants and trees remove
water from the soil, and paper towels
soak up water.
In summary…
Water molecules have the ability
to “climb” structures (adhesion)
and this can result in capillary
action.
Adhesion also causes
water to…
Hold onto plant
leaves (the droplets
form due to
cohesion)
Attach to a
silken spider
web
Meniscus
Turgor Pressure
Celery
Turgor pressure is the pressure that
happens when the water located inside
the cells begins to expand, pushing on the
cell membranes or walls.
Turgor pressure is important to the plant
cells because it is what gives them the
rigidness to stand straight and continue
normal cellular functions.
If a plant is not able to access enough
water to maintain the turgid state then it
will begin to wilt, which interferes with
function.
Water is called the UNIVERSAL SOLVENT
More substances dissolve in water than in any
other chemical.
This is also caused by water’s polarity. The positive part
of an ionic compound is attracted to the oxygen side of a
water molecule, and the the negative part of an ionic
compound is attracted to the hydrogen side.
Water is called the UNIVERSAL SOLVENT
Water is the solvent
for biochemical
processes.
Hemoglobin,
carbonates, various
proteins, and many
other molecules in the
body use water as a
solvent.
Water has High Heat Capacity
Specific Heat Capacity is the amount of heat
needed to raise or lower 1g of a substance
1°C
Water resists temperature change, both for
heating and cooling.
This allows water to act as a buffer for body
temperature.
Water is Less Dense as a Solid
Ice is less dense as a solid than as a
liquid.
Frozen water (ice) floats on liquid water.
Frozen water forms a crystal-like lattice
where 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
This is important for organisms that live underwater. If frozen
water sunk, small bodies of water would be more likely to
freeze completely in the winter, which would be bad for all
the organisms living there. A layer of ice effectively insulates
the underlying water, allowing many aquatic organisms to
survive through the winter.
Homeostasis
the ability to maintain a steady state
despite changing conditions
Water is important to this
process because:
Human Tissue
% Water
Blood
83.0
Heart
79.2
Muscle
75.6
Brain
-Water is a good insulator
-Water resists temperature change Skin
Bone
-Water is a universal solvent
-Ice protects against temperature extremes
(insulates frozen lakes)
74.8
72.0
22.0