Chemistry of the atmosphere

• Has the atmosphere changed a lot since the formation of the Earth 4.6 billion years ago? Yes
• What was the condition of the atmopshere like during the formation of the Earth? It consisted a lot of CO2, as well as comprising some other gases
• What was a key factor that shaped the atmosphere 4 billion years ago? [4] Intense volanic activity that releases: - Mainly Carbon Dioxide - Water vapour - Small proportions of methane and ammonia
• What occured between 3-4 billions years ago? [2] - Decrease in CO2 and other gases - Increase in Oxygen and Nitrogen
• What was the condition of the amosphere 2 billion years ago? The amount of CO2 decreased, with nitrogen and oxygen increasing.
• What were some key factors that shaped the atmosphere 2 billion years ago? [6] Green plants and algae evolve and: - Carbon dioxide is reduced as the plants take it in and give out oxygen - Microorganisms that can't tolerate oxygen are killed off - Carbon from CO2 becomes locked up in sedimentary rocks formed from the shells and skeletons of marine organisms - Other gases react with oxygen to release nitrogen - Nitrogen is also produced by bacteria removing nitrates from decaying plant material
• What occured between 1 billions years ago? [2] - Decrease in carbon dioxide - Increase in nitrogen and oxygen
• What is the condition of the amosphere now? [3] - Comprises of about 80% nitrogen - 20% oxygen - Small proportions of other gases such as water vapour, CO2
• How long has the proportions of gases in the atmosphere been more or less the same for? 200 million years
• What is the quantity of water vapour present in our atmosphere? 0-3%
• Do algae and plants photosynthesise? Yes
• What happens during photosynthesis? Carbon Dioxide and water react to produce glucose and oxygen
• When did algae first started producing oxygen? 2.7 billion years ago
• What happened over the next billion years? [Plants] Plants evolved and the amount of oxygen in the atmosphere increased
• What happened as the level of oxygen in the atmosphere increased? There was enough to allow animals to evolve
• What has happened to the level of carbon dioxide as plants and algae have evolved? It has decreased
• Why has the level of carbon dioxide decrease as plants and algae evolve? Because plants use carbon dioxide during photosynthesis
• Why else has carbon dioxide decreased? [Rocks] As carbon becomes locked up in sedimentary rocks and fossil fuels
• What does limestone contain? Calcium Carbonate
• What can calcium carbonate (limestone) be formed from? Shells and skeletons of sea creatures
• What is coal? A sedimentary rock formed from plants deposits that were buried and compressed over millions of years
• True or false: The level of carbon dioxide in the atmosphere has also reduced by the reaction between CO2 and sea water? True
• What does the reaction between carbon dioxide and sea water produce? [2] - Insoluble carbonates that are deposited as sediment - Soluble hydrogen carbonates
• Why is carbon dioxide dissolving in the oceans dangerous? As it can harm marine life such as coral reefs
• What is emitted from the sun that passes through the atmosphere and reaches the Earth's surface? High energy, short wavelength infrared radiation
• What happens to the infrared radiation from the Sun that passes through our atmosphere and reaches the surface? It is absorbed by the Earth
• What happens to lower energy, longer wavelength infrared radiation? [R] It is reflected by the Earth's surface
• What do greenhouse gases in the Earth's atmosphere absorb? The outgoing infrared radiation, which increases the Earth's temperature
• What would happen to the Earth if there was no greenhouse gases? Earth would be too cold for water to be a liquid and would not be able to support life
• What do greenhouse gases include? [3] - Carbon Dioxide - Water Vapour - Methane
• What can human activites increase? Levels of greenhouse gases in the atmosphere
• Has the amount of carbon dioxide in the atmosphere increased over the last 100 years? Yes.
• What does the increase in CO2 in our atmosphere correlate to? To the increase in the amount of fossil fuels being burnt
• What do fossil fuels contain? Carbon that has been locked up for millions of years
• What is released when you burn fossil fuels? Carbon Dioxide
• What can deforestation lead to? An increase in carbon dioxide into the atmosphere as there are fewer trees to taking up the gas for photosynthesis
• What activities that increase the levels of methane in the atmosphere? [2] - Decomposition of rubbish in landfill sites - Increase in animal farming
• What do many scientists believe that the increase in levels of greenhouse gases will cause? That the temperature of the Earth's surface will increase and result in global climate change
• Why is it difficult to produce and accurate model for such a complicated system? Because many factors are involved
• Why may some people views be biased when speaking about climate change? As they may be paid by companies that produce greenhouse gases