Earth’s Atmosphere (Early + Modern Time)

Question 1

What do they believe was happening on Earth 4.6 billion years ago?

Answer 1

Intense volcanic activity

Question 2

What did the intense volcanic activity release?

Answer 2

• Mainly carbon dioxide
• Water vapour
• Small proportions of methane and ammonia

Question 3

What happened to the relased water vapour from volcanic activity as Earth cooled down?

Answer 3

It condensed to form oceans

Question 4

What happened to the carbon dioxide levels as oceans formed, and why?

Answer 4

CO2 levels decreased

- it dissolved into the oceans

Question 5

Why did oxygen levels increase, and carbon dioxide continued to decrease?

Answer 5

• Plants and algae evolved
• Photosynthesise
• Take in CO2, release O2

Question 6

What locked up the carbon dioxide?

Answer 6

The formation of sedimentary rocks ( from shells and skeletons of marine organisms)

Question 7

What three ways were CO2 levels decreased?

Answer 7

• Dissolving into oceans
• Photosynthesis from plants and algae
• Locking up in formed sedimentary rocks

Question 8

What happened to nitrogen levels overtime, and why?

Answer 8

N2 levels increased

• volcanic activity
• produced by bacteria removing nitrates from decaying plant material

Question 9

What is the current % of gases on today’s atmosphere?

Answer 9

78% N2 (g)
21% O2 (g)
0.9 % Ar (g)
<0.01 % CO2 + other gases (g)