1. Notes Science SPI 0807.9.5 Atmospheric Composition
Tennessee SPI Objective:
Describe the chemical makeup of the atmosphere.
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Check for Understanding
Explain how the chemical makeup of the atmosphere
illustrates a mixture of gases.
Essential Question(s)
1) What is the chemical composition of our atmosphere?
2) What evidence demonstrates that our atmosphere is a mixture and not a compund?

2. Atmospheric Composition (Even the Moon has a very thin atmosphere.)
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Atmospheric Composition
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What is an Atmosphere?
An atmosphere is the mass of gases that surrounds a planet.
and is held in place by gravity.
Planetary atmospheres are common in our solar system
(Even the Moon has a very thin atmosphere.)
Mars
Saturn
Jupiter
Earth
The Moon

3. Atmospheric Composition
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Earth's Atmosphere
Earth’s atmosphere is a mixture of various gases
Earth's Current Atmosphere
…(approx) 78% nitrogen
…(approx) 21% oxygen
…(approx) 1% other gases (Argon, etc)
(argon, water vapor, carbon dioxide, etc)
Nitrogen 7 N
14.0
Oxygen 8 O
16.0
Argon 18 Ar
39.9
Remember! Our atmosphere is a MIXTURE & not a compound

4. Atmospheric Composition
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Earth's Current Atmosphere
…displayed with pie charts/circle graphs
…(approx) 78% nitrogen
…(approx) 21% oxygen
…(approx) 1% other gases (Argon etc.)
Nitrogen 7 N
14.0
Oxygen 8 O
16.0
Argon 18 Ar
39.9

5. What are the “other” gases?
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Earth's Current Atmosphere
…approx) 1% other gases (Argon etc.)
What are the “other” gases?
Note: They are called Trace Gases
Argon (Ar)
Neon (Ne)
Carbon Dioxide (CO2)
Helium (He)
Water Vapor (H2O)
Methane (CH4)
…and any other odor, pleasant or unpleasant, that you have ever smelled.

6. Atmospheric Composition (View Holt Online Ch15: Sect 3 VC)
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Where did Earth's atmosphere come from?
from comets and planetismals
Venting from volcanoes
oxygen from plants
(View Holt Online Ch15: Sect 3 VC)

7. Notes Science What are comets? SPI 0807.9.5 Atmospheric Composition
Where did Earth's atmosphere come from?
from comets and planetismals (water from space)
What are comets?
Comets are giant "dirty snowballs" in space.
They consist of frozen water, stellar dust, and rocky debris.

8. Atmospheric Composition
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Where did Earth's atmosphere come from?
Venting from volcanoes
3 most common gases from volcanoes
(1) Water Vapor, (2) Carbon Dioxide, and (3) Sulfur Dioxide

9. Notes Science SPI 0807.9.5 Atmospheric Composition
Where did Earth's atmosphere come from?
oxygen from plants-photosynthesis
(plants absorb carbon dioxide and release oxygen)

10. Earth's Changing Atmosphere
Millions of year’s ago, Earth’s atmosphere was mostly carbon dioxide, water vapor, and ammonia.
What changed it?
Plants converted the carbon dioxide to oxygen , and this oxygen broke down the ammonia into nitrogen.

11. Atmospheric Composition
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Atmospheric Composition
Section number two in the circle graph above BEST represents
the percentage of…?
A) Carbon B) Oxygen C) Argon D) Nitrogen 1 3 2
Review
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Oxygen

12. In diagram 01 below, which gas is represented in the
Portion labeled 1 on the pie chart?
A) Argon B) Nitrogen C) Hydrogen D) Oxygen
Diagram 01
Diagram 02
Nitrogen

13. Atmospheric Composition
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Atmospheric Composition
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Questions

14. Atmospheric Composition
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15. Argon and various trace gases make up about 1% of Earth’s atmosphere.
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Questions
Argon
Neon
Carbon Dioxide
Helium
Water Vapor
Methane