AQA GCSE Chemistry

Revision Notes

9.1.1 Gases in the Atmosphere

Composition of Air

  • The proportion of gases in the air has not changed much in 200 million years
  • About four fifths of the air is nitrogen and one fifth is oxygen
  • The remaining gases include carbon dioxide, water vapour and trace quantities of the noble gases

Pie chart showing composition of air, IGCSE & GCSE Chemistry revision notes

Pie chart showing the composition of clean air

  • Scientists know the historic composition of the air by analysing the tiny air bubbles trapped in ice cores taken at the poles
  • The air bubbles were trapped as the snow and ice was laid down tens of thousands of years ago and provide a snapshot of what our atmosphere was like back then

Exam Tip

Although the proportion of carbon dioxide is very small, it plays a substantial role in global warming as a greenhouse gas.

Author: Francesca

Fran has taught A level Chemistry in the UK for over 10 years. As head of science, she used her passion for education to drive improvement for staff and students, supporting them to achieve their full potential. Fran has also co-written science textbooks and worked as an examiner for UK exam boards.

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