Core. Half the diameter of the earth, High proportion of the magnetic metals iron and nickel. Liquid outer part and solid inner part.
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What surrounds the Earth>
The atmosphere.
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What is the Earth's crust and upper part of the mantle cracked into?
Tectonic plates
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What causes tectonic plates to move?
Convection currents in the mantle. The convection currents are caused by energy released by the decay of radioactive elements eating up the mantle.
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What was Alfred Wegners idea?
Continental drift - The idea that the continents had moved to their position as the result of convection currents.
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Why were Wegner's ideas not accepted for many years?
1. They believed that the Earth was shrinking as it cooled.
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In the first billion years what was the atmosphere like?
The surface was covered with volcanoes that released carbon dioxide, water vapour and nitrogen.
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How did oceans form?
Most of the water vapour in the atmosphere condensed.
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What other elements did scientists believe were present int he early atmosphere?
nirtogen, methane and ammonia.
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What produced the oxygen in the atmosphere?
Algae and plants used carbon
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Why are we not sure about how life began?
Insufficient evidence
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What was the miller-urey experiment
An experiment based on what thy believed the early atmosphere was like.
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Describe the miller-urey experiment
1. mixture of water, ammonia, methane and hydrogen 2. High voltage spark as lightning 3. Amino acids , the building blocks for proteins, were formed.
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What is a 'primordial soup'
ORganic molecules formed a primordial doup and that the amino acids in this mixture combined to make proteins.
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In what ways did carbon form carbon dioxde become 'locked up'?
1. PLants 2. Animals eat plants 3. Animal remainds - sedimentary rocks (limestone) and fossil fuels. 4. Carbon dioxide dissolves in oceans - formed insoluble carbonate compounds deposited on seabeds.
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What are the percentages of gases int he air?
4/5 nitrogen 1/5 oxygen carbon dioxide, water vapour, noble gases make up 1%
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Why can gases in the air be separated by fractional distillation?
GAses int he air have different boiling points and so can be separated form liquid air.
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Why is fractional distillation of air done?
To produce pure oxygen and liquid nitrogen
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Describe how fractional distillation of air occurs
1. air is cooled below -200° 2. fed into fractional distillation column 3. Nitrogen is separated form oxygen and argon 4. further distillation to produce pure oxygen and argon
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Name two processes that release carbon dioxide into the atmosphere and two processes that remove it?
Release : Respiration, COmbustion Remove: Photosynthesis, Death
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Which human activity has been the main cause of increased carbon dioxide levels int he atmosphere?
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