C9- Chemistry of the Atmostphere

The Evolution of the Atmostphere

Phase 1- Volcanoes gave out gases

- The first billion years of earths history were exlosive- the surface was covered in volcanoes that erupted and released ost of gas.

- The early atomstphere was mostly carob dioxide with virtually no oxygen

- Volcanic activity also released nitrogen, which built up in the atmostphere over time, as well as water vapour and small amounts of methane and ammonia.

Phase 2- Oceans, Algae and Green Plants absorbed carbon dioxide

- When the water vapour in the atmostphere condensed it formed oceans.

-Lots of carbon dioxide was removed from the early atomsphere as it dissolved in the oceans. This dissolved carbon dioxide then went through a series of reactions to form carbonate precipitates that formed sediments on the seabed.

- Green plants and algae evolved and absorbed some of the carbon dioxde so that they could carry out photosynthesis. Later marine animals evolved. Their shells and skeltons contained carbonates from the oceans

-Some of the carbon these organisms took in from the atomostphere and oceans became locked up in rocks and fossil fuels after the organisms died.

Phase 3- Green plants and algae produced oxygen

- As well as absorbing the carbon dioxde in the atmostphere, green plants and algae produced oxygen by photsynthesis

-As oxygen levels built up in the atmostphere over time, more complex life could evolve

-Evetually 200 million years ago, the atmostphere reached a composition similar to what it is today; approximately 80% nitrogen, 20% oxygen and small amounts of other gases including carbon dioxide, noble gases and water vapour

Greenhouse Gases and Climate Change

Greenhouse…