The Earth's atmosphere is the gaseous layer surrounding our planet...
Chemistry234 views·Updated 20 Aug 2026·4 pagesGCSE Chemistry Notes: Atmosphere - Topic 9 AQA Overview
1 / 4
1
of 4
The Atmosphere's Composition
Our atmosphere today consists mostly of nitrogen (78%) and oxygen (21%), with small amounts of other gases including carbon dioxide, water vapour and noble gases. This composition has remained relatively stable for about 200 million years, but it wasn't always this way.
During Earth's first billion years, intense volcanic activity released gases that formed the early atmosphere, primarily water vapour and carbon dioxide. As the planet cooled, water vapour condensed to form oceans, but carbon dioxide remained dominant in the atmosphere—similar to what we see today on Mars and Venus.
Carbon dioxide levels decreased over time through several natural processes. The gas dissolved in oceans, creating a weak acid that reacted with minerals to form precipitates. These eventually became sediments of carbonate rock on the sea bed. Marine organisms like corals and mussels also used carbon dioxide to create their shells, which later formed limestone when they died.
Did you know? The limestone formations we see today represent carbon dioxide that was once in the atmosphere, showing how Earth naturally sequestered carbon over millions of years!
2
of 4
The Rise of Oxygen and Fossil Fuels
About 1.7 billion years ago, a major atmospheric shift began when photosynthetic algae evolved in the oceans. These simple organisms produced oxygen as a byproduct of photosynthesis. As plants later evolved on land, oxygen levels continued to increase until they reached a point where animal life could develop.
While oxygen levels rose, carbon dioxide was being trapped in what we now call fossil fuels. Coal formed when plant material in marshy wetlands didn't fully decompose due to lack of oxygen or acidic conditions. Under high pressure and temperature over millions of years, this plant matter transformed into coal.
Crude oil and natural gas formed similarly but from marine organisms. When plankton died and settled in mud on the sea floor, their remains were preserved without decomposition if oxygen was absent. Gradually, heat and pressure transformed these remains—plankton became crude oil, while natural gas (primarily methane) often formed nearby.
Important: The greenhouse effect is actually natural and necessary! Without it, Earth would be too cold for life. Gases like carbon dioxide, water vapour and methane trap the sun's heat by allowing short-wavelength radiation in but absorbing the long-wavelength radiation that the Earth radiates back.
3
of 4
Climate Change and Solutions
Human activities have significantly altered atmospheric composition, particularly through deforestation and fossil fuel use. Cutting down forests not only removes carbon-absorbing trees but also releases stored CO₂. Meanwhile, agriculture—especially cattle farming—produces large amounts of methane, another powerful greenhouse gas.
The impacts of these changes are already visible: melting polar ice, rising sea levels, more severe weather patterns, and shifting distributions of plants, animals and diseases like malaria. While climate models are complex and sometimes lead to simplified predictions, the evidence for human-caused climate change is overwhelming.
Reducing our carbon footprint—the total amount of greenhouse gases produced through our activities—requires both individual and societal changes. Simple steps include better home insulation, using public transport instead of cars, switching to renewable energy sources, and reducing electricity consumption. Eating less beef and dairy also helps reduce methane emissions.
Take action: Calculate your personal carbon footprint online to see which of your daily activities contribute most to greenhouse gas emissions. You might be surprised by what makes the biggest impact!
4
of 4
Air Pollution from Fuels
When we burn fossil fuels like coal and hydrocarbons, they release several harmful pollutants. The carbon and hydrogen in these fuels react with oxygen in the air to produce various compounds, some quite dangerous to human health.
Carbon monoxide is a toxic gas produced by incomplete combustion. It has no colour or smell, making it particularly dangerous—which is why carbon monoxide detectors in homes are so important. When coal containing sulfur is burned, it produces sulfur dioxide, which causes breathing problems and contributes to acid rain.
Vehicles create another set of pollutants. The high temperatures in car engines cause nitrogen and oxygen in the air to react, forming various nitrogen oxides (NOx). These, along with sulfur dioxide, dissolve in rainwater to create acid rain that damages trees and buildings. Cars also release particulates—tiny unburned hydrocarbon particles that increase the risk of heart and lung disease.
Health alert: Air pollution isn't just an environmental issue—it's a major health concern. The World Health Organization estimates that air pollution contributes to millions of premature deaths annually, primarily from respiratory and cardiovascular diseases.
We thought you’d never ask...
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
You can download the app from Google Play Store and Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
Similar content
Most popular content: Atmospheric Chemistry
4ChemistryAQA GCSE Chemistry Revision
Comprehensive revision notes for AQA GCSE Chemistry Paper 2, covering key topics such as organic chemistry, environmental chemistry, chemical reactions, and the structure of DNA. Ideal for higher-tier students preparing for exams, this resource includes essential concepts like hydrocarbons, equilibrium, and sustainable development.
91,81352
ChemistryEarth's Atmospheric Evolution
Explore the formation and evolution of Earth's atmosphere, focusing on volcanic activity, the rise of oxygen through photosynthesis, and the decrease of carbon dioxide. This summary covers key concepts in atmospheric chemistry relevant for GCSE Higher Chemistry students.
112431
ChemistryAtmospheric Evolution Overview
Explore the transformation of Earth's atmosphere from volcanic origins to the rise of oxygen. This summary covers key processes including volcanic gas emissions, the role of oceans, and the evolution of algae and green plants in altering atmospheric composition. Ideal for students studying atmospheric chemistry and environmental science.
91291
ChemistryOrganic Chemistry Insights
Explore key concepts in organic chemistry, including hydrocarbons, chemical reactions, and equilibrium. This mind map covers essential topics for AQA Chemistry Paper 2, such as the properties of hydrocarbons, cracking processes, and the impact of chemical resources on the environment. Ideal for students preparing for exams, this resource provides a clear overview of atmospheric chemistry, rates of reaction, and water resource management.
1149516
Most popular content in Chemistry
9ChemistryChemistry paper 2
Chem paper 2 notes
1173414
ChemistryA-level OCR A Chemistry summary sheets
Everything from snaprevise for OCR chemistry a-level
122,41284
Chemistrychem paper 1
higher
112,24145
ChemistryRedox Reactions Overview
Explore the fundamentals of redox reactions, including oxidation states, definitions of oxidation and reduction, and the roles of oxidizing and reducing agents. This summary covers key rules for determining oxidation states, the concept of disproportionation, and practical applications in chemical equations. Ideal for A-Level Chemistry students preparing for exams.
126,371320
ChemistryEssential Chemistry Practicals
Explore key AQA GCSE Chemistry practicals, including flame tests, titration, and gas identification. This resource covers essential techniques for analyzing ions, making salts, and understanding reaction kinetics. Perfect for students preparing for exams and practical assessments.
1011,991902
ChemistryAcids, Bases & Salts Overview
Explore the essential concepts of acids, bases, and salts, including acid-base reactions, neutralization processes, and methods for making soluble salts. This summary covers key definitions, pH levels, and indicators, providing a comprehensive understanding for GCSE students. Ideal for exam preparation and quick revision.
1162711
BiologyPaper 2 chemistry mindmaps
Condesnsed aqa triple higher
958110
ChemistryIGCSE Chemistry Concepts
Explore essential IGCSE Chemistry concepts including states of matter, chemical bonding, acid-base reactions, and separation methods. This comprehensive summary covers key topics such as ionic and covalent bonds, solubility rules, and the periodic table, tailored for Edexcel IGCSE Double Award students. Perfect for exam preparation and understanding fundamental chemistry principles.
111,45744
ChemistryGCSE Chemistry Revision Essentials
Comprehensive overview of key GCSE Chemistry topics including atomic structure, chemical bonding, reaction kinetics, and the periodic table. Ideal for Higher Tier students preparing for exams. Key concepts include mole calculations, electrolysis, and the Haber process.
93,01788
Most popular content
9
SociologyComprehensive Crime & Deviance Overview
Explore an extensive revision of crime and deviance topics, including theories, types of crime, and the impact of media. This resource covers key concepts such as Marxism, functionalism, gender and crime, and the influence of globalization on criminal behavior. Ideal for students seeking a thorough understanding of criminology and its various theories. Type: Full Topic Revision.
1251,7541,403
SociologySociological Theories Overview
Comprehensive revision of key sociological theories including Functionalism, Marxism, Feminism, and Interpretivism. Explore concepts like value freedom, identity formation, and the critique of social control. Ideal for AQA A-Level Sociology students preparing for exams. This summary covers essential theories and their implications in sociology, providing a clear understanding of each perspective.
1231,594848
SociologySociology of Families: Comprehensive Revision
Dive into an extensive overview of family dynamics, perspectives, and patterns in sociology. This resource covers key concepts such as family diversity, gender roles, marriage, and the impact of social policies on family structures. Perfect for A-Level Sociology students preparing for Paper 2.
1273,9952,306
SociologySociology of Education Overview
Explore comprehensive A-Level Sociology notes on the education system, covering key theories, policies, and sociological perspectives. This resource includes insights on marketisation, gender roles, cultural deprivation, and educational inequalities, providing a thorough understanding of how education shapes social stratification and individual achievement. Ideal for exam preparation and in-depth study.
12103,1563,044
SociologyCrime and Deviance AQA A-level sociology
AQA A-level crime and deviance topic notes
1289319
ChemistryChemistry paper 2
Chem paper 2 notes
1173414
BiologyA-Level Biology Year 1 Overview
Comprehensive summary of AQA A-Level Biology Year 1, covering key topics such as cellular structure, protein synthesis, immune response, gas exchange, and more. Ideal for exam preparation and understanding biological concepts. Includes detailed insights into cellular processes, biological classification, and the circulatory system.
1215,115700
BiologyAQA Biology: Key Concepts
Explore essential AQA Biology topics including Photosynthesis, Respiration, Homeostasis, Genetics, and Ecology. This comprehensive knowledge organizer covers key concepts such as energy transfer, hormonal control, and genetic variation, providing a solid foundation for your studies. Ideal for exam preparation and understanding biological processes.
109,107310
BiologyBiology P2: Evolution & Adaptation
Explore key concepts in AQA GCSE Biology P2, focusing on evolution, natural selection, genetic engineering, and adaptations in organisms. This summary covers essential topics such as DNA structure, speciation, and the impact of environmental changes on biodiversity. Ideal for exam preparation and understanding complex biological processes.
111,24222
Students love us — and so will you.
4.6/5App Store
4.7/5Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan SiOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha KlichAndroid user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
AnnaiOS user
Chemistry234 views·Updated 20 Aug 2026·4 pagesGCSE Chemistry Notes: Atmosphere - Topic 9 AQA Overview
The Earth's atmosphere is the gaseous layer surrounding our planet that enables all life. Its composition has changed dramatically over billions of years, from a carbon dioxide-rich environment to the nitrogen-oxygen rich air we breathe today. Understanding these changes helps...
1
of 4
Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
By signing up you accept Terms of Service and Privacy Policy
The Atmosphere's Composition
Our atmosphere today consists mostly of nitrogen (78%) and oxygen (21%), with small amounts of other gases including carbon dioxide, water vapour and noble gases. This composition has remained relatively stable for about 200 million years, but it wasn't always this way.
During Earth's first billion years, intense volcanic activity released gases that formed the early atmosphere, primarily water vapour and carbon dioxide. As the planet cooled, water vapour condensed to form oceans, but carbon dioxide remained dominant in the atmosphere—similar to what we see today on Mars and Venus.
Carbon dioxide levels decreased over time through several natural processes. The gas dissolved in oceans, creating a weak acid that reacted with minerals to form precipitates. These eventually became sediments of carbonate rock on the sea bed. Marine organisms like corals and mussels also used carbon dioxide to create their shells, which later formed limestone when they died.
Did you know? The limestone formations we see today represent carbon dioxide that was once in the atmosphere, showing how Earth naturally sequestered carbon over millions of years!
2
of 4Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
By signing up you accept Terms of Service and Privacy Policy
The Rise of Oxygen and Fossil Fuels
About 1.7 billion years ago, a major atmospheric shift began when photosynthetic algae evolved in the oceans. These simple organisms produced oxygen as a byproduct of photosynthesis. As plants later evolved on land, oxygen levels continued to increase until they reached a point where animal life could develop.
While oxygen levels rose, carbon dioxide was being trapped in what we now call fossil fuels. Coal formed when plant material in marshy wetlands didn't fully decompose due to lack of oxygen or acidic conditions. Under high pressure and temperature over millions of years, this plant matter transformed into coal.
Crude oil and natural gas formed similarly but from marine organisms. When plankton died and settled in mud on the sea floor, their remains were preserved without decomposition if oxygen was absent. Gradually, heat and pressure transformed these remains—plankton became crude oil, while natural gas (primarily methane) often formed nearby.
Important: The greenhouse effect is actually natural and necessary! Without it, Earth would be too cold for life. Gases like carbon dioxide, water vapour and methane trap the sun's heat by allowing short-wavelength radiation in but absorbing the long-wavelength radiation that the Earth radiates back.
3
of 4Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Climate Change and Solutions
Human activities have significantly altered atmospheric composition, particularly through deforestation and fossil fuel use. Cutting down forests not only removes carbon-absorbing trees but also releases stored CO₂. Meanwhile, agriculture—especially cattle farming—produces large amounts of methane, another powerful greenhouse gas.
The impacts of these changes are already visible: melting polar ice, rising sea levels, more severe weather patterns, and shifting distributions of plants, animals and diseases like malaria. While climate models are complex and sometimes lead to simplified predictions, the evidence for human-caused climate change is overwhelming.
Reducing our carbon footprint—the total amount of greenhouse gases produced through our activities—requires both individual and societal changes. Simple steps include better home insulation, using public transport instead of cars, switching to renewable energy sources, and reducing electricity consumption. Eating less beef and dairy also helps reduce methane emissions.
Take action: Calculate your personal carbon footprint online to see which of your daily activities contribute most to greenhouse gas emissions. You might be surprised by what makes the biggest impact!
4
of 4Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Air Pollution from Fuels
When we burn fossil fuels like coal and hydrocarbons, they release several harmful pollutants. The carbon and hydrogen in these fuels react with oxygen in the air to produce various compounds, some quite dangerous to human health.
Carbon monoxide is a toxic gas produced by incomplete combustion. It has no colour or smell, making it particularly dangerous—which is why carbon monoxide detectors in homes are so important. When coal containing sulfur is burned, it produces sulfur dioxide, which causes breathing problems and contributes to acid rain.
Vehicles create another set of pollutants. The high temperatures in car engines cause nitrogen and oxygen in the air to react, forming various nitrogen oxides (NOx). These, along with sulfur dioxide, dissolve in rainwater to create acid rain that damages trees and buildings. Cars also release particulates—tiny unburned hydrocarbon particles that increase the risk of heart and lung disease.
Health alert: Air pollution isn't just an environmental issue—it's a major health concern. The World Health Organization estimates that air pollution contributes to millions of premature deaths annually, primarily from respiratory and cardiovascular diseases.
We thought you’d never ask...
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
You can download the app from Google Play Store and Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
Similar content
Most popular content: Atmospheric Chemistry
4ChemistryAQA GCSE Chemistry Revision
Comprehensive revision notes for AQA GCSE Chemistry Paper 2, covering key topics such as organic chemistry, environmental chemistry, chemical reactions, and the structure of DNA. Ideal for higher-tier students preparing for exams, this resource includes essential concepts like hydrocarbons, equilibrium, and sustainable development.
91,81352
ChemistryEarth's Atmospheric Evolution
Explore the formation and evolution of Earth's atmosphere, focusing on volcanic activity, the rise of oxygen through photosynthesis, and the decrease of carbon dioxide. This summary covers key concepts in atmospheric chemistry relevant for GCSE Higher Chemistry students.
112431
ChemistryAtmospheric Evolution Overview
Explore the transformation of Earth's atmosphere from volcanic origins to the rise of oxygen. This summary covers key processes including volcanic gas emissions, the role of oceans, and the evolution of algae and green plants in altering atmospheric composition. Ideal for students studying atmospheric chemistry and environmental science.
91291
ChemistryOrganic Chemistry Insights
Explore key concepts in organic chemistry, including hydrocarbons, chemical reactions, and equilibrium. This mind map covers essential topics for AQA Chemistry Paper 2, such as the properties of hydrocarbons, cracking processes, and the impact of chemical resources on the environment. Ideal for students preparing for exams, this resource provides a clear overview of atmospheric chemistry, rates of reaction, and water resource management.
1149516
Most popular content in Chemistry
9ChemistryChemistry paper 2
Chem paper 2 notes
1173414
ChemistryA-level OCR A Chemistry summary sheets
Everything from snaprevise for OCR chemistry a-level
122,41284
Chemistrychem paper 1
higher
112,24145
ChemistryRedox Reactions Overview
Explore the fundamentals of redox reactions, including oxidation states, definitions of oxidation and reduction, and the roles of oxidizing and reducing agents. This summary covers key rules for determining oxidation states, the concept of disproportionation, and practical applications in chemical equations. Ideal for A-Level Chemistry students preparing for exams.
126,371320
ChemistryEssential Chemistry Practicals
Explore key AQA GCSE Chemistry practicals, including flame tests, titration, and gas identification. This resource covers essential techniques for analyzing ions, making salts, and understanding reaction kinetics. Perfect for students preparing for exams and practical assessments.
1011,991902
ChemistryAcids, Bases & Salts Overview
Explore the essential concepts of acids, bases, and salts, including acid-base reactions, neutralization processes, and methods for making soluble salts. This summary covers key definitions, pH levels, and indicators, providing a comprehensive understanding for GCSE students. Ideal for exam preparation and quick revision.
1162711
BiologyPaper 2 chemistry mindmaps
Condesnsed aqa triple higher
958110
ChemistryIGCSE Chemistry Concepts
Explore essential IGCSE Chemistry concepts including states of matter, chemical bonding, acid-base reactions, and separation methods. This comprehensive summary covers key topics such as ionic and covalent bonds, solubility rules, and the periodic table, tailored for Edexcel IGCSE Double Award students. Perfect for exam preparation and understanding fundamental chemistry principles.
111,45744
ChemistryGCSE Chemistry Revision Essentials
Comprehensive overview of key GCSE Chemistry topics including atomic structure, chemical bonding, reaction kinetics, and the periodic table. Ideal for Higher Tier students preparing for exams. Key concepts include mole calculations, electrolysis, and the Haber process.
93,01788
Most popular content
9SociologyComprehensive Crime & Deviance Overview
Explore an extensive revision of crime and deviance topics, including theories, types of crime, and the impact of media. This resource covers key concepts such as Marxism, functionalism, gender and crime, and the influence of globalization on criminal behavior. Ideal for students seeking a thorough understanding of criminology and its various theories. Type: Full Topic Revision.
1251,7541,403
SociologySociological Theories Overview
Comprehensive revision of key sociological theories including Functionalism, Marxism, Feminism, and Interpretivism. Explore concepts like value freedom, identity formation, and the critique of social control. Ideal for AQA A-Level Sociology students preparing for exams. This summary covers essential theories and their implications in sociology, providing a clear understanding of each perspective.
1231,594848
SociologySociology of Families: Comprehensive Revision
Dive into an extensive overview of family dynamics, perspectives, and patterns in sociology. This resource covers key concepts such as family diversity, gender roles, marriage, and the impact of social policies on family structures. Perfect for A-Level Sociology students preparing for Paper 2.
1273,9952,306
SociologySociology of Education Overview
Explore comprehensive A-Level Sociology notes on the education system, covering key theories, policies, and sociological perspectives. This resource includes insights on marketisation, gender roles, cultural deprivation, and educational inequalities, providing a thorough understanding of how education shapes social stratification and individual achievement. Ideal for exam preparation and in-depth study.
12103,1563,044
SociologyCrime and Deviance AQA A-level sociology
AQA A-level crime and deviance topic notes
1289319
ChemistryChemistry paper 2
Chem paper 2 notes
1173414
BiologyA-Level Biology Year 1 Overview
Comprehensive summary of AQA A-Level Biology Year 1, covering key topics such as cellular structure, protein synthesis, immune response, gas exchange, and more. Ideal for exam preparation and understanding biological concepts. Includes detailed insights into cellular processes, biological classification, and the circulatory system.
1215,115700
BiologyAQA Biology: Key Concepts
Explore essential AQA Biology topics including Photosynthesis, Respiration, Homeostasis, Genetics, and Ecology. This comprehensive knowledge organizer covers key concepts such as energy transfer, hormonal control, and genetic variation, providing a solid foundation for your studies. Ideal for exam preparation and understanding biological processes.
109,107310
BiologyBiology P2: Evolution & Adaptation
Explore key concepts in AQA GCSE Biology P2, focusing on evolution, natural selection, genetic engineering, and adaptations in organisms. This summary covers essential topics such as DNA structure, speciation, and the impact of environmental changes on biodiversity. Ideal for exam preparation and understanding complex biological processes.
111,24222
Students love us — and so will you.
4.6/5App Store
4.7/5Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan SiOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha KlichAndroid user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
AnnaiOS user