Presentation on theme: "The Wonderful World of Water. The importance of water Water covers 71% of Earth’s surface."— Presentation transcript:
The Wonderful World of Water
The importance of water Water covers 71% of Earth’s surface
But not all of that water is usable
You are mostly made of water
In fact, water is crucial to life as we know it!
Life on Earth originated in the oceans
This is why astronomers look for planets in the “goldilocks zone” where liquid water could exist
It is thought that Mars once had liquid water So life may have once existed there.
This simple molecule is involved in all aspects of our life. It shapes land through erosion and weathering
It influences our climate (long term weather patterns) –Forms different types of air masses over land and sea, reflects sunlight using clouds and glaciers, forms precipitation, ocean currents and temperature influence local climates
Ancient civilizations settled near water and worshiped rain gods. Wars have been fought over access to water
So what makes this simple molecule so amazing? Water has some unique properties A water molecule (H 2 O), is made up of three atoms --- one oxygen and two hydrogen. H H
Water is Polar In each water molecule, the oxygen atom attracts more than its "fair share" of electrons The oxygen end has a negative charge The hydrogen end has a positive charge However, water is neutral (equal number of e- and p+) = Zero Net Charge
These charges allow water molecules to “stick” together The negative oxygen end of one water molecule is attracted to the positive hydrogen end of another water molecule to form a HYDROGEN BOND
These hydrogen bonds allow for some interesting behavior by water Phases of Matter Heat Capacity Cohesion Adhesion
Phases of Matter Water exists in all three phases on Earth At sea level, pure water boils at 100 °C and freezes at 0 °C.
Water vapor is made of water (H 2 0) in gas form. The molecule is still made of three atoms.
Properties of Water The boiling temperature of water decreases at higher elevations (lower atmospheric pressure).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 (it takes longer to cook food at a lower temperature)For this reason, an egg will take longer to boil at higher altitudes (it takes longer to cook food at a lower temperature)
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?Which is ice and which is water?
Water is Less Dense as a Solid WaterIce
Cohesion Cohesion: an attraction between molecules of the same kind. Hydrogen bonds allow one water molecule to stick to other water molecules This results in surface tension (a measure of the strength of water’s surface) https://www.youtube.com/watch?v=ciqNNRlS2yA Surface tension
Surface tension created by cohesion… Helps animals remain on the surface of the water 45yabrnryXk
Adhesion Adhesion is the attraction between two different substances. Water will form hydrogen bonds with other surfaces such as glass, soil, plant tissues, and cotton.
Cohesion vs. Adhesion Cohesion- two alike substances attracted to one another Adhesion- two different substances attracted to one another
Adhesion allows plants to pull in water Capillary action - water molecules will “tow” each other along when in a thin glass tube or along a paper towel. The thinner the tube, the higher the water can “climb”
Capillary Action in a paper towel The water is adhering to the paper towel.
This calendar uses capillary action to absorb ink, one day at a time
Adhesion Causes Capillary Action Transpiration is the water released from plant leaves
Transpiration: water vapor is released by plants.
Adhesion Two types of water-conducting cells Cohesion 300 m Direction of water movement
Water has high heat capacity 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. Which takes longer to heat up? A pot with water or a pot with no water?
Heat Capacity of water influences the climate of areas near water
Figure 3.5 Santa Barbara 73° Los Angeles (Airport) 75° Pacific Ocean 68° Santa Ana 84° Burbank 90° San Bernardino 100° Palm Springs 106° Riverside 96° San Diego 72° 40 miles 70s (°F) 80s 90s 100s
Why does Phoenix AZ have a greater temperature range than San Diego CA?
Water, like all matter, cannot be created or destroyed The same water molecules you drink today have been around for billions of years! It originally arrived on earth from comets! Measurements from the Herschel Space Observatory show that comet Hartley 2, which comes from the distant Kuiper Belt, contains water with the same chemical signature as water in Earth's oceans. The findings may help explain how Earth’s surface ended up covered in water.
Water is constantly recycled The Water Cycle is the continuous process by which water moves from Earth’s surface to the atmosphere and back. Driven by energy from the SUN.
Processes of the Water Cycle 1.The Sun heats up the water in Earth’s oceans and lakes.
Processes of the Water Cycle 2. Evaporation: liquid water changes to a gas called water vapor.
Processes of the Water Cycle Transpiration: water vapor is released by plants.
Processes of the Water Cycle 3. Condensation: Warm air carries water vapor upward.Warm air carries water vapor upward. The air cools and condenses into liquid water.The air cools and condenses into liquid water. Tiny droplets of water clump together around tiny dust particles in the air, forming clouds.Tiny droplets of water clump together around tiny dust particles in the air, forming clouds.
Licancabur Volcano is located on the border between Chile and Bolivia.
Processes of the Water Cycle 4. Precipitation: As more water vapor condenses, the drops of water grow larger and heavier. The heavy droplets fall as precipitation (rain, snow, sleet, hail).
Processes of the Water Cycle 5. The precipitation that falls on land may: soak into the soil and become groundwater OR Run off the land, eventually flowing back into the ocean.
Water that falls on the surface may run off into rivers and streams, eventually flowing back to a lake or ocean.