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Do Now – 15 Minutes
Topic – The Hydrosphere – Properties of
Water• Using the first 15 minutes class, we would
like you to take a case of markers from the front of the room, and your poster, and complete your water cycle drawing.
• Be sure someone at your table has the grading rubric!
• Take out your Earthquake lab – I will collect it while you’re working.
Water�Oddly enough, one of the most plentiful
things on the surface of the Earth, is
chemically also one of the strangest.
�These unique properties
of water help harbor the
life that exists here today.
Chemistry of Water�A molecule of water is made up of which
three elements:
Chemistry of Water�As a result, oxygen (6 electrons) meets
up with two hydrogens (1 electron each)
to create an electrically balanced outer
shell (8 electrons total).
Chemistry of Water�However, the charge on the molecule is
not evenly distributed – it’s off-balance.
�This is referred to a polar bond.
Chemistry of Water�This polar bond can be seen when a
charged object is brought near a water
source.
�What happens to the water?
�The spare charge I give it
pulls on the water, making
the water physically bend!
Chemistry of Water�If we have two or more hydrogen
molecules next to each other, what could
we expect to happen, knowing that
opposite charges attract?
�The unbalanced charge will be attracted
to each other.
Chemistry of Water�This type of interaction is known as a
hydrogen bond.
Chemistry of Water�A hydrogen bond is a weak bond
between two molecules due to their
electrostatic attraction wherein a proton
in one molecule is attracted to an
electronegative atom in another
molecule.
Chemistry of Water�This means that water will “stick to itself”,
also known as cohesion.
�How is this fact about
water useful in Envi. Sci.?
Chemistry of Water�Additionally, water will “stick” to other
surfaces as well. This is known as
adhesion.
�Where could you find this in your life?
�How is this useful in
the environment?
Chemistry of Water�Another property of water is that is has a
HIGH specific heat capacity.
�Meaning, it takes a LOT of energy in
order to heat it up.
�Water also holds onto its temperature for
a long time before cooling it off.
�But you already knew that – right?
Chemistry of Water�When most objects are subjected to heat,
their bonds will split.
�Most of that energy when transferred to
water, will cause the molecules to vibrate
first, then separate.
Chemistry of Water�The fact that water can absorb so much
heat is the reason why the following
demonstration works.
�Observe! And do not try this at home.
Chemistry of Water�Lastly, water has one more fairly unique
quality.
�How does the density of solid water
compare to the density of liquid water?
�Solid water is
LESS DENSEthan liquid water!
Chemistry of Water
�When ice forms into a solid, it starts to
crystalize into a fixed, repeating pattern.
Chemistry of Water
�This pattern when water is a solid
occupies more space than liquid water,
making it less dense than liquid water.
Chemistry of Water
�Why is this important in thinking about
Envi. Sci.?
Examples
�What is this picture an example of? Why?
Examples
�What is this picture an example of?
�How does this relate to the water cycle?