Chemistry of the Atmosphere

• Sulfur dioxide and oxides of nitrogen cause acid rain
• Carbon monoxide combines irreversibly with haemoglobin in red blood cells
• Nitrogen makes up approximately 78% of the Earth's atmosphere
• Carbon dioxide and the noble gases make up approximately 1% of the Earth's atmosphere.
• Carbon dioxide made up most of the Earth's early atmosphere
• Around 20% of the atmosphere today is oxygen
• Algae first began producing oxygen around 2.7 billion years ago.
• Carbon dioxide also dissolved in the oceans, forming carbonates.

  The carbonates joined together and precipitated from the water as sedimentary rocks (like limestone)
• The proportions of different gases in the atmosphere have been the same for 200 million years.
• One theory suggests that Earth's early atmosphere was much like the atmosphere today on Mars and Venus.
• One theory states that the Earth's early atmosphere was mainly carbon dioxide with small amounts of water vapour, ammonia, methane and nitrogen.