Atmospheric Chemistry
The atmosphere is a mix of gases that cycle through reactions.
About this topic
Earth's atmosphere is about 78 percent nitrogen, 21 percent oxygen, 0.93 percent argon and 0.04 percent carbon dioxide, plus variable water vapour. It is layered: the troposphere (weather), the stratosphere (ozone layer), mesosphere and thermosphere. Key processes include the greenhouse effect, ozone formation and depletion, smog and acid rain.
Greenhouse gases such as carbon dioxide, methane and water vapour absorb infrared radiation emitted by Earth and re-radiate it, keeping the planet about 33 degrees Celsius warmer than it would otherwise be. Burning fossil fuels has raised carbon dioxide from about 280 ppm before industrialisation to over 420 ppm, enhancing warming. Stratospheric ozone, O3, forms when UV splits O2 and the atoms combine with O2, and absorbs harmful UV-B. Chlorofluorocarbons release chlorine atoms that catalytically destroy ozone: Cl + O3 gives ClO + O2, and the Montreal Protocol has phased them out.
Photochemical smog forms when nitrogen oxides and volatile organic compounds react in sunlight, making ground-level ozone, which harms lungs. Particulates and sulfur dioxide add to air pollution. Catalytic converters, cleaner fuels and renewable energy help.
Misconceptions: that the ozone hole causes global warming (they are separate problems), and that the greenhouse effect is bad in itself; it is essential, and the problem is enhancement. Also, ozone high up is protective, while near the ground it is a pollutant.
Key ideas
- 78% nitrogen, 21% oxygen
- Ozone absorbs UV
- CFCs destroy ozone
Quick check
Use cases: where Atmospheric Chemistry helps
- Homework: review the key idea behind Atmospheric Chemistry before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Atmospheric Chemistry without notes.
- Visual learning: play with the interactive lab to see how Atmospheric Chemistry changes when you adjust its inputs.
- Teaching a friend: explain Atmospheric Chemistry in your own words, then compare your version with the key ideas.
Chemistry explains medicine, food, cleaning products, fuels and building materials.
Frequently asked questions
What is Atmospheric Chemistry?
The atmosphere is a mix of gases that cycle through reactions.
What will I learn in Atmospheric Chemistry?
78% nitrogen, 21% oxygen. Ozone absorbs UV. CFCs destroy ozone.
Is Atmospheric Chemistry part of Chemistry?
Yes. It is one of 150 Chemistry topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Atmospheric Chemistry lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Atmospheric Chemistry?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.