1 chemistry/chemistry acc blocks 1/2/4 chapter 1.1 the story of two chemicals chunk notes 01/10/11...
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3 The Ozone Layer Ultraviolet radiation, given off by the sun, causes sunburns, harms plants, destroys crops, and causes cancer. The ozone layer is a chemical -- O 3 -- in the Earth’s atmosphere that absorbs most of the radiation before it reachers the Earth’s surface. 3TRANSCRIPT
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Chemistry/Chemistry ACC Blocks 1/2/4Chapter 1.1
The Story of Two ChemicalsChunk Notes
01/10/11Dr. Kukla
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The Ozone Layer
•Chemical: Any substance that has a definite composition (i.e., what it’s made out of).
•H2O = Water
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The Ozone Layer
•Ultraviolet radiation, given off by the sun, causes sunburns, harms plants, destroys crops, and causes cancer.
•The ozone layer is a chemical -- O3 -- in the Earth’s atmosphere that absorbs most of the radiation before it reachers the Earth’s surface.
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The Ozone Layer•The Earth’s atmosphere is divided
into layers, from lowest to highest:
•Troposphere (contains the air we breathe)
•Stratosphere (where 90% of the ozone layer is)
•Mesosphere
•Thermosphere
•Erosphere
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The Ozone Layer
•Ozone is formed when ultraviolet radiation breaks oxyegen gas into smaller particles, which then interact with each other to form ozone: O3
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The Ozone Layer•The Ozone layer was first
identified in the late 1800s.
•Since air currents are found in the stratosphere, the ozone layer was studied as a marker of air flow over the planet.
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The Ozone Layer•In the 1920s, G.M.B.
Dobson measured the ozone layer; he measured levels of more than 300 Dobson Units (DU).
•Most ozone is stored in the lower part of the ozone.
•It is measured by balloons, satellites, and rockets.
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The Ozone Layer•A group of British
scientists began measuring the ozone layer during 1981-1983 over Antarctica in the Spring.
•In 1985 they determined the ozone layer was thinning.
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The Ozone Layer
•The thinning of the ozone is like a worn-out old sock.
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Chlorofluorocarbons
•During the 1920s, toxic chemicals were used as coolants in refrigerator and air-conditioning units.
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Chlorofluorocarbons
•In 1928, Thomas Midgley Jr. created the first chloroflurocarbons (CFCs), which contain chlorine, fluorine, and carbon.
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Chlorofluorocarbons
•They do not occur naturally, are non-toxic, and are stable (i.e., they do not react with other chemicals very easily).
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Chlorofluorocarbons
•The US began using them in 1935.
•They were used as coolants, plastics, styrofoam cups/plates, propellants in aerosol cans.
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Chlorofluorocarbons
•During the 1970s, scientists began to notice that the ozone layer was thinning and an increase in CFCs in the atmosphere.