Chemistry T9: Chemistry of the atmosphere

• How did the early atmosphere form and what gases were released?

  The early atmosphere formed through volcanic activity and released gases such as water vapour, carbon dioxide, ammonia and methane.
• How did oceans form?

  Eventually the earth cooled down, where water vapour condensed to form oceans.
• Where did nitrogen come from?

  When volcanoes released erupted they released(NH3)

  1) Reacted with oxygen to from Nitrogen and water

  2) Bacteria break down compounds with nitrogen to release nitrogen.
• Why did the amount of carbon dioxide in the atmosphere decrease?

  1) Dissolved in the ocean, where it reacted with metal ions

  2) Carbon reacted with sedimentary rock

  3) Plants photosynthesised (takes in co2)
• How did the amount of oxygen in the atmosphere increase?


  Plants such as algae evolved and released oxygen when they photosynthesised (take in co2 release o2). As oxygen increased, amount of plants increased.
• Describe the earths early atmosphere and how it was formed


  - the earth was very hot when formed

  - there was significant volcanic activity

  - gases were released from these volcanoes (CO₂, CH₄, NH₃, H₂O)
• Describe the proportions of the gases in the modern atmosphere

  78% nitrogen (N₂), 21% oxygen (O₂), 1% other
• Some bacteria called nitrifying bacteria broke down compounds with nitrogen, and released it.
• How does the greenhouse effect work?

  Gases act like insulators.

  They absorb long wavelength (thermal) radiation from the sun and re-radiate it in all directions including the earth.
• What is carbon footprint?


  The amount of carbon dioxide released over the full life cycle of something
• Carbon monoxide from incomplete combustion of fossil fuels can cause respiratory problems (they bind to haemoglobin in red blood cells) .
• Sulfur oxides are produced by burning sulfur containing compounds, e.g. coal or oil. They react with rainwater to form acidic solutions which damage plants and aquatic organisms.