2.4 chemistry of the atmosphere

• how do scientists think the early atmosphere was formed?

  the surface was covered in volcanoes that erupted and released lots of gases, like nitrogen (which built up in the atmosphere), water vapour, and small amounts of methane and ammonia.
• what was the early atmosphere made up of?

  mostly carbon dioxide, with virtually no oxygen, this is similar to the atmosphere of mars and venus today.
• how were oceans formed?

  water vapour in the atmosphere condensed
• how was a lot of carbon dioxide removed from the early atmosphere and what happened to it?

  it dissolved in the oceans, and it went through a series of reactions to form carbonate precipitates that formed sediments on a seabed
• how did green plants and algae evolve?

  they absorbed some of the carbon dioxide so that they could carry out photosynthesis