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?