Gases in the Atmosphere

Gas Symbol %

Nitrogen N₂ 78%

Oxygen O₂ 21

Argon Ar .93

Carbon Dioxide CO₂ .03

Water Vapor H₂O 0-4% (varies)

Trace Gases: less than 0.0001% in our atmosphere

1. Hydrogen

2. Ozone

3. Methane

4. Neon

5. Helium

6. Krypton

7. Xenon

Composition of Atmosphere

Atmosphere

- a mixture of gases, solids and liquids

Important Gases

- Nitrogen, Oxygen, Carbon Dioxide and Ozone

Nitrogen

* 78% of atmosphere

· Nitrogen compounds important for plant nutrients

· Nitrogen Cycle: pg. 394-395 in handout (pg 6)

· Bacteria in soil form Nitrogen compounds

o Return nitrogen to air and cycle goes again

Oxygen

· 21% of atmosphere

· Important for all life forms

· Animals

o Use oxygen from air or dissolved in water

· Produced by plants during photosynthesis

· Causes rocks to break down= weathering!

Carbon Dioxide

· Small amount in atmosphere but very important

· Plants need it to produce oxygen

· Essential for life process

· Carbon Dioxide-Oxygen cycle pg. 394 on handout (pg 6)

Ozone

· A form of oxygen that absorbs ultraviolet radiation

o UV radiation is harmful

· Can Cause: skin cancer, genetic mutations, eye problems

· Many things destroy ozone

o Supersonic jets, fertilizers, fluorocarbons

o When ozone is destroyed more UV rays can reach Earth

· Human activity can also destroy ozone

o Air conditioners, aerosols

o Many countries have now banned the use of CFC’s

§ Chlorofluorocarbons

* Important for all life forms