Gases in the Atmosphere (AQA GCSE Chemistry): Revision Notes
📚 Revision Notes
9.1.1 Gases in the Atmosphere
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The modern atmosphere has existed in its current form for approximately the last 200 million years, with the proportions of gases remaining relatively stable during this time.
The Modern Atmosphere is made up of:
- Nitrogen (N₂):
- Proportion: Makes up almost 80% of the atmosphere.
- Role: Nitrogen is the most abundant gas in the atmosphere.
- Oxygen (O₂):
- Proportion: Accounts for about 20% of the atmosphere.
- Role: Oxygen is crucial for respiration in living organisms, allowing them to survive and thrive.
- Trace Gases:
- The atmosphere also contains several trace gases—gases present in proportions of less than 1%.
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Examples:
- Water vapour (H₂O)
- Carbon dioxide (CO₂)
- Noble gases (e.g., argon)
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These trace gases, although present in small amounts, play important roles in processes like climate regulation, maintaining the greenhouse effect, and supporting various chemical reactions in the environment.