AtmosphereKey Facts
Current Atmospheric Composition
Part of Composition of Atmosphere — GCSE Chemistry
This key facts covers Current Atmospheric Composition within Composition of Atmosphere for GCSE Chemistry. Revise Composition of Atmosphere in Atmosphere for GCSE Chemistry with 20 exam-style questions and 12 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 2 of 13 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 2 of 13
Practice
20 questions
Recall
12 flashcards
📊 Current Atmospheric Composition
The atmosphere has been relatively stable for the last 200 million years:
- Nitrogen (N₂) — About 78%. Unreactive gas; released from volcanoes and denitrifying bacteria
- Oxygen (O₂) — About 21%. Produced by photosynthesis; essential for aerobic respiration
- Argon (Ar) — About 0.9%. Noble gas, extremely unreactive
- Carbon dioxide (CO₂) — About 0.04%. Currently increasing due to human activities
- Water vapour — Variable (~1–4%). Depends on temperature and location
Memory key: 78-21-1 = Nitrogen-Oxygen-Argon (NOA)