Chemistry of the Atmosphere

• Compsition of the atmosphere

  • 78% Nitrogen
  • 21% Oxygen
  • 0.9% Argon
  • 0.04% CO2
• The earth is approximatley 4.6 billion years old
• Evolution of the atmosphere

  • The surface of the early Earth was molten for millions of years with no atmosphere
  • As cooling slowly occured the molten surface began to slowly solidify into land masses
  • Volcanoes formed on the land masses
  • Combustion reaction took place while the volcanoes erupted, these released large amounts of carbon dioxide and water vapour, as well as nitrogen, hydrogen and other gases like ammonia and methane
  • When conditions cooled sufficiently, the water vapour later condensed and fell to the surface of the Earth, forming the oceans
• How did Oxygen Increase

  • Primitive plants and algae began photosynthesising which used up carbon dioxide from the atmosphere and released oxygen
  • As more and more plants began to appear the levels of oxygen began to increase which allowed for more complex life forms to evolve
• How carbon dioxide decreased

  • When the water vapour in Earth’s early atmosphere condensed, large amounts of CO2 dissolved in the oceans
  • Green plants and algae began to evolve and absorbed considerable amounts of carbon dioxide during photosynthesis
  • Dead organisms turn into fossil fuels, such as crude oil, natural gas and coal which 'locked up' the carbon