The Story of Our Air
🌍 The Story of Our Air
4.6 billion years ago, Earth's atmosphere was completely different from today — a choking mix of carbon dioxide, water vapour, and ammonia, with no oxygen whatsoever. Through processes like photosynthesis, volcanic outgassing, and the formation of the oceans, life itself transformed our atmosphere from a toxic environment into the oxygen-rich air that supports complex life. Understanding this story is one of the most dramatic examples of how chemistry and biology have shaped the planet we live on.
Chemistry glossary
- What percentage of the atmosphere is CO₂?
- About 0.04%
Earth's surface was covered by molten rock and volcanoes. Volcanic activity released gases to form the early atmosphere:
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🧠 Memory Aid
78-21-1: Nitrogen-Oxygen-Argon (NOA)
For atmospheric evolution, remember the sequence: "Volcanoes → Oceans → Algae → Life → Stability"
For what removed CO₂: "POLS" — Photosynthesis, Oceans (dissolved), Limestone (carbonate rocks), Sediment (fossil fuels)
Quick Check: Give TWO reasons why CO₂ decreased from the early atmosphere to present levels.
1. CO₂ dissolved in the oceans and reacted with minerals to form carbonate rocks (limestone). 2. Photosynthesis by cyanobacteria and plants converted CO₂ to glucose and oxygen.
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Quiz · Question 1 of 20
What is the approximate percentage of nitrogen in the current atmosphere?
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