Evolution of the Atmosphere

• How do scientists think the atmosphere was formed during the first billion years or so of Earth’s history?

  Volcanoes produced lots of gases
• Name five gases that scientists think were present in the early atmosphere?

  Water vapor, carbon dioxide, nitrogen, methane, ammonia.
• Descibe How levels of carbon dioxide in the atmosphere were reduced

  Plants and algae evolved and started to take in carbon dioxide in exchange for oxygen
• Write the balanced chemical equation for photosynthesis

  6Co2 + 6H20 ——> C6H12O6 + 6O2
• State the approximate composition of the atmosphere today

  80% Nitrogen 20% Oxygen and a small amount of other gases