is amazing! In fact, you can't live without it. Water's special
molecular structure allows it to form bonds with any positively
or negatively charged atom. Water is a universal solvent meaning
it dissolves other substances and transports both good and bad
molecules. So, what's in the water? A lot!
hydrogen (H) atoms attach to one oxygen (O) atom to form a water
molecule (H2O.) Each hydrogen atom forms
a covalent bond with the oxygen atom--they share a pair of electrons.
Oxygen has an extra pair of electrons that are not shared. The
extra electrons are on the side away from the hydrogen atoms
. This makes the oxygen side of a water molecule negative. The
hydrogen side is positive. Water's polarity means it dissolves
most everything--good and bad, positive and negative.
Check out the
water cycle section to see how water moves from land to air and
can exist in three states.
Ordered molecular state
as a Solid
Water can be a solid like ice or snow. Frozen water is in
an ordered molecular state. This means all atoms are bonded.
There are no or few atoms free to bond with other atoms.
This makes it difficult for the atoms within polluting substances
bond with the atoms within water. Therefore, polluting substances
are not dissolved by water when it's in a frozen or ordered
next time you put an ice cube in a glass of soda, notice
the soda doesn't "mix" with the solid ice cube.
The water remains solid until temperature forces the water
to change states. The ice melts. The soda mixes with water
only after the ice, solid water, melts into a liquid state.
as a Liquid
Water can be a liquid like you would find in a flowing river,
a calm lake, or even in a glass for drinking. Water as a
liquid is in a semi-ordered molecular structure. This means
some water molecules have atoms available to bond with the
atoms of other substances. Water as a liquid can dissolve
these substances. If the substances contain pollution, the
result is a solution made up of pollution and water.
as a liquid gives free transportation to pollution. Take
a spoonful of baking soda and empty it onto the counter.
It's confined to one place. But if you add that same spoonful
to a glass of water and then pour it onto the counter, the
baking soda gets transported all over the place. It may
even run off the counter onto the floor where you definitely
don't want it. Imagine it you added something worse than
mere baking soda!
as a Gas
Water can even be a gas which is the water vapor you can
see when boiling water. Water vapor is in a random molecular
structure. Water vapor is a gas diffused in the air. Its
molecules are distributed randomly or "spread out."
In this state, all of the water molecule atoms are available
for bonding with other substances. However, like in its
frozen state it does little bonding. Why? Because the molecules
are distributed so randomly that there is less of a chance
of water molecules and other substances finding each other.
But they do sometimes bond. Sometimes
the pollution is already in water and vapor merely transports
it up to the clouds.
adhesion, and dissolved oxygen
atomic structure is unique and simple. A water molecule is made
up of just three parts: an oxygen atom and two hydrogen atoms.
This structure is unique because it produces electrochemical
properties. The structure makes a water molecule have a positive
side and a negative side. Water is actively attracted to other
molecules. At the same time, other molecules are attracted to
water molecules have a positive side and a negative side, any
atom with a positive or negative charge can bond with it. In
fact, water is a universal solvent. This means water can combine
with other chemicals to form a solution. Chemical nutrients
can then be carried as a solution through runoff into surface
water, or infiltrate ground water.
The pH of water molecules is not basic (alkaline) or acidic. It
is neutral until water dissolves other substances. Since water can
bond with just about anything, you rarely get pure water, or the
chemical state H2O, without other bonded molecules
of something else. So water usually picks up other molecules, like
carbon dioxide for example, as it travels through the water cycle.
with as pH less than 7 is considered acidic. Rain has a pH of 5.6
which is considered "normal." However, sometimes rain
is far more acidic. When rain has a lower pH than 5.6 it is called
"acid rain." Water vapor as it reaches the clouds can
come into any number of pollutants we put into the air such as carbon
dioxide (CO2), sulfur dioxide (SO2),
and nitrogen oxides (NO1-X). The water vapor
attracts the positive hydrogen ions of these pollutive substances
to form acid rain. The pollution comes from many sources including
sediment, and additives
what ends up in the water, what bonds with water molecules, as water
travels through the water cycle? Minerals, sediment, and additives
are on the "what's in the water" list.
Water's unique structure allows it to create strong bonds. These
bonds create density. Therefore, water can transport heavy minerals
like salt, calcium, potassium, or zinc. They transport these minerals
not only through rivers and over land, but through your body as
Unfortunately, sediment can be transported as well. Sediment is
usually in the form of dirt and it is not wanted in our waterways.
Additives used to purify drinking water, like chlorine, travel
with water from a processing plant to your faucet. Sometimes other
additives like fluoride are introduced into a communities drinking
water for the purpose of reducing tooth decay.