AQA GCSE Chemistry

Revision Notes

9.1.1 Gases in the Atmosphere

Test Yourself

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.

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