Phase 1- Volcanoes gave out gases

The early atmosphere was formed by volcanoes erupting and releasing gases
Early atmosphere was mainly carbon dioxide and little to no oxygen
Volcanic activity also released nitrogen , water vapour and small amounts of methane and ammonia

Phase 2-Oceans, algae and green plants absorbed carbon dioxide

When the water vapour condensed it formed oceans
Lots of the carbon doxide from the early atmosphere was removed as it dissolved in the oceans
This dissolved carbon went through a series of reactions to form carbon precipitates.
Green plants and algae dissolved some of the carbon dioxide so that they could carry out photosynthesis
Marine animals evolved, their shells and skeletons contained carbonates from the oceans
Some of the carbon the organisms took in from the atmosphere and oceans got trapped in rocks and fossil fuels after the organism died

Notes

When plants, plankton and marine animals, they fall to the seabed and are buried by layers of sediment
Over time it becomes compresses, trapping the carbon within them and reducing the carbon dioxide levels in the atmosphere

Phase 3-Green plants and algae produced oxygen

As well as absorbing the carbon dioxide, green plants nd algae produced oxygen by photosynthesis
Algae evolved first
As the oxygen levels in the atmosphere built up more complex organisms evolved.

	Created by Paige Snowling almost 8 years ago

Chemistry Paper 2 notes-fairly detailed Covers all topics needed to pass chemistry paper 2