Chemistry of the atmosphere

• How did volcanic activity change the Earth's early atmosphere?

  Volcanic activity releases nitrogen, carbon dioxide, and water into the atmosphere
• How did plankton affect the Earth's atmosphere?

  Microscopic marine organisms that evolved in the oceans and photosynthesized to produce oxygen
• Why did the carbon dioxide levels change in the early atmosphere?

  Carbon dioxide dissolved in the oceans and formed insoluble carbonates, that formed sediments
• How and why did the oxygen levels change?

  Oxygen levels increased when plankton evolved and photosynthesised
• What are fossil fuels?

  Carbon-containing compounds formed from dead marine animals that were covered in mud and compressed under high pressure and temperature for millions of years in the absence of oxygen
• How did nitrogen levels change over time


  Nitrogen is an unreactive gas released from volcanic activity, which slowly built up in the Earth's atmosphere over time
• Why did the carbon dioxide levels change decrease over time

  Levels decreased over time due to

  1. carbon dioxide dissolving in oceans and forming insoluble carbonates

  2. carbon dioxide taken in during photosynthesis

  3. trapped (locked-in) in fossil fuels
• What is photosynthesis


  Process by which plants absorb carbon dioxide and produce oxygen
• How are insoluble carbonates formed?

  Carbon dioxide dissolved in oceans to form insoluble carbonates
• What is a greenhouse gas?

  A gas that absorbs infrared radiation, contributing to global warming

  
  

  Global warming causes extreme weather events such as flooding, droughts, hurricanes
• How is methane formed?


  Greenhouse gas produced from rice fields, landfills, and cattle farming
• How do greenhouse gases produce global warming?

  Short wave radiation from the sun passes through the atmosphere

  Re-emitted as long-wave radiation from the surface

  Which is absorbed by the greenhouse gases, making them more energetic

  Atmosphere warms up
• How is sulfur dioxide formed, and how does it form acid rain?

  A compound formed from the oxidation of sulfur impurities in fossil fuels (S+ O2 -> SO2)

  Sulfur dioxide reacts with water and oxygen in the atmosphere to produce acid rain

  
  

  Acid rain destroys limestone buildings

  
  

  sulfur dioxide also causes global dimming
• What is incomplete combustion?


  Process where insufficient oxygen leads to the formation of toxic gases like carbon monoxide and carbon
• How is carbon monoxide formed and why is the gas dangerous


  Toxic gas produced from incomplete combustion due to insufficient oxygen, limiting oxygen uptake in the blood

  
  

  Carbon monoxide is odourless and colourless, making it hard to detect
• What is acid rain?


  Rainfall with high acidity, caused by sulfur dioxide reacting with water and oxygen in the atmosphere

  
  

  Kills plants and trees
• What is the greenhouse effect

  Phenomenon where greenhouse gases trap heat in the Earth's atmosphere

  
  

  Short wave radiation from the sun passes through the atmosphere

  Re-emitted from the Earth's surface as long wave radiation

  Which is absorbed by the greenhouse gases (carbon dioxide, methane) in the atmosphere
• How is carbon formed during combustion, and what is the health consequence?

  Formed from the incomplete combustion of hydrocarbons/fuels

  
  

  Sometimes called soot

  
  

  Causes lung diseases
• What is a hydrocarbon?

  Compounds in fossil fuels containing carbon and hydrogen atoms only
• Define Activation energy


  Minimum energy required for a chemical reaction to occur