Nitrogen makes up approximately 78% of the Earth's atmosphere, yet it is not classified as a greenhouse gas. Explain why nitrogen does not contribute to the greenhouse effect, and state two gases that are classified as greenhouse gases.

Pearson Edexcel International GCSE Chemistry (4CH1) — 2.3 Gases in the atmosphere · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

The Earth's atmosphere is composed of several gases. Some of these gases are described as greenhouse gases, whilst others, including nitrogen, are not.

Model answer (4 marks)

Nitrogen does not absorb or trap infra‑red radiation from the Earth's surface, so it does not raise or maintain the temperature of the atmosphere.

Water vapour and carbon dioxide are two gases that are classified as greenhouse gases.

Examiner tips

  • Use the phrase "does not absorb or trap infra‑red radiation" – this is the key point. Show the logical link: no IR absorption → no warming. Name two correct gases, e.g. water vapour and carbon dioxide.
  • common_mistakes
  • :
  • Saying nitrogen is a greenhouse gas by mistake. Listing a non‑greenhouse gas such as oxygen or argon as a greenhouse gas.

Mark scheme (4 marks)

  1. Greenhouse gases trap infra-red radiation (from the Earth's surface) / nitrogen does not absorb or trap infra-red radiation
  2. Therefore nitrogen does not raise/maintain the temperature of the atmosphere / does not contribute to warming the Earth
  3. First correct greenhouse gas named: water vapour OR carbon dioxide
  4. Second correct greenhouse gas named: methane (or a different correct gas from the list above not already given)

Key terms in this question

greenhouse effect · greenhouse gases

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