1.7 Changes in the Earth and its Atmsophere Flashcards
What is the structure of the Earth?
- Core
- Mantle
- Crust
What are tectonic plates?
Big sections of the Earth’s crust that are seperated from each other and are free to move around
What causes tectonic plates to move?
Heat is released by natural radioactive processes in the core, this heat cause convection currents in the mantle that move the tectonic plates.
What are the proportions of gases in the atmosphere for the last 200 million years?
- ~80% Nitrogen
- ~20% Oxygen
- Tiny bits of carbon dioxide, water vapour and noble gases
What happened in phase 1 of Earth’s atmosphere?
Intense volcanic activity. Volcanoes released a lot of gases that formed the early atmosphere which was mainly carbon dioxide and water vapour. The water vapour condensed to form the oceans
What happened in phase 2 of Earth’s atmosphere?
Green plants/algae evolved. They produced oxygen. They trapped carbon in the ground when they died. A lot of carbon dissolved in the oceans.
What happened in phase 3 of Earth’s atmosphere?
The build-up of oxygen allowed complex life to evolve. The oxygen created an oxone layer which blocks harmful rays from the sun. There is virtually no carbon dioxide left
What is the theory of primordial soup?
Primordial soup is a theory of how life was first formed:
Billions of years ago the atmosphere was rich in nitrogen, hydrogen, ammonia and methane. Lighting struck, causing a chemical reaction between the gases, resulting in ammino acids. The amino acids collected together, where life first began
How can raw materials be obtained from air?
Air can be fractionally distilled to get a variety of products for use in industry.
- Air is filtered to remove dust
- It’s cooled to -200ºC and becomes a liquid
- Water vapour condenses and is removed
- Carbon dioxide freezes and is removed
- Liquified air enters the fractionating column and is heated slowly
- Oxygen/argon and nitrogen seperate
