1. Do Now: We use models to describe or represent things 1. Describe what you see in the beaker/container on the counter. 2. What do you think this beaker could be modeling?

2. Ozone and the Atmosphere

3. Cornell Notes

4. Ms. Akagi Ozone and the Atmosphere 9/14/09 Pg. 1 Layers of the atmosphere Layers of the atmosphere Troposphere Stratosphere Mesosphere Thermosphere Exosphere Troposphere Stratosphere Mesosphere Thermosphere Exosphere

5. Ozone and the Atmosphere

6. What is a model? Models are a tool scientists use Use them to put things that are too big or too small to see with our eyes into a form we can examine

7. The Atmosphere A mixture of gases that surround the earth ◦ 78% nitrogen ◦ 21% oxygen ◦ 1% other gases (CO 2, water vapor, etc)

8. Layers of the Atmosphere 1. Troposphere – nearest the earth, we live, weather 2. Stratosphere – above the troposphere, ozone layer, jets fly 3. Mesosphere – meteors burn up 4. Thermosphere – auroras, space shuttles, satellites 5. Exosphere – highest layer

9. The Troposphere The thickest layer (2 miles high) 77% of the atmosphere Closest to the Earth’s surface It’s the layer we live in

10. The Stratosphere The stratosphere contains the Ozone layer Ozone layer – protects us from UV radiation from the sun.

11. Ozone A clear, colorless gas made of three oxygen atoms Absorbs UV radiation and reacts to form oxygen gas

12. Model it! Making Ozone 1 M&M = 1 oxygen atom 1. Oxygen gas = 2 oxygen atoms 2. Make three oxygen gas molecules O2O2 O2O2 O2O2 O2O2

13. Model It! Making Ozone 3. When the sun’s radiation hits one of the oxygen gas molecules, it splits into two oxygen atoms 4. These oxygen atoms combine with the oxygen gas molecules to form two ozone molecules! O2O2 O2O2 OO O3O3 O3O3

14. Model it! How Ozone Protects us! 1. We start with 2 ozone molecules (3 atoms of oxygen each) 2. The Sun’s radiation hits the ozone molecules, breaking them up into oxygen gas and one oxygen atom each. O3O3 O3O3 O2O2 O2O2 OO

15. Model it! How Ozone Protects us! 3. The two free oxygen atoms combine to form a molecule of oxygen gas (2 atoms) Ozone absorbs energy and breaks down into oxygen gas! O2O2 O2O2 O2O2

16. Problem with the Ozone layer? There’s a hole!!!!

17. Chlorofluorocarbons (CFCs) Man made, non-toxic, stable chemicals Made of chlorine, fluorine and carbon Used in air conditioners, refrigerators, plastic foams, and aerosol cans Used so much, scientists began to measure the amount of CFCs in the air

18. Are they Connected? Ozone Hole Amount of CFCs in the Air

19. Think about it The layer of the atmosphere closest to earth is called the…. Troposphere! The stratosphere contains the __________ layer Ozone! Ozone protects us by…. Absorbing the sun’s energy! There may be a link between the hole in the ozone layer and the increase in ______________ Chlorofluorocarbons! (CFCs)

20. Reflection (at bottom of notes) What have you learned today? Why is it important? What questions do you have?