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GCSE: Changing Materials - The Earth and its Atmosphere
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Key things you need to know about the atmosphere
- 1 The air around us is composed of 70% nitrogen, 29% oxygen and 1% other gases (mostly noble gases and 0.04% carbon dioxide)
- 2 Two of the best ways now being used to reduce carbon dioxide emissions are: “capture and storage”- where we capture the CO2 and trap it in abandoned oil wells. And “sequestration”- where we react the CO2 with CaO to make CaCO3 (CaO + CO2 = CaCO3)
- 3 The layer of atmosphere that we live in is called the troposphere. Above that is the stratosphere, followed by the mesosphere, then the thermosphere and finally the exosphere. The ozone layer is located in the lower stratosphere.
- 4 The ozone layer is a layer of O3 molecules that absorb harmful ultraviolet radiation that would otherwise kill most human life on Earth (by giving us cancer).
- 5 Gases like CFC’s (chlorofluorocarbons) destroy the ozone layer. It takes decades for CFC’s to be removed from the atmosphere once they are up there- and all the time they are constantly destroying more ozone. There is currently a hole in the ozone layer caused by gases like CFC’s that is as big as the arctic (north) pole…and growing.
Five top tips on pollution
- 1 Carbon monoxide is a toxic gas as it blocks the haemoglobin in our blood from transporting oxygen around our body…if you take in too much carbon monoxide you will suffocate even if you keep on breathing!
- 2 Nitrogen oxide and nitrogen dioxide gases in the atmosphere cause acid rain. This destroys trees and makes lakes too acidic for fish to live in. It is also responsible for corroding buildings.
- 3 Carbon dioxide is the biggest cause of global warming and if its levels are not reduced, it could cause the melting of the polar ice caps. This will flood an estimated minimum of 30% of England. It is the biggest worry of atmospheric scientists of our time.
- 4 Particulates, mainly found in car exhausts, get stuck in our lungs and cause cancer.
- 5 Low level ozone (O3) is incredibly dangerous, especially for people who have asthma.
What is global warming?
- 1 Global warming is caused by greenhouse gases absorbing infrared radiation emitted from the Earth and scattering it back down to Earth. As infrared radiation is basically heat, this heats the surface of the Earth up.
- 2 As well as carbon dioxide, other greenhouse gases include water and methane. They absorb the infrared radiation by making their bonds vibrate.
- 3 As global warming causes the polar ice caps to melt, clathrate deposits (huge amount of trapped methane gas) are released. This causes further global warming in a positive feedback loop.
- 4 As the average temperature on land raises, many crops will not be able to grow. Almost all scientists agree that this will cause widespread famine on a scale never seen before. This will affect all countries, not just developing countries.
- 5 A common mistake students make is to confuse the greenhouse effect with the hole in the ozone layer. Ozone has nothing to do with the greenhouse effect. Keep these two topics clearly separated in your mind.
All products of petroleum are either alkanes or cycloalkanes. Therefore, all those products pose a major risk if mishandled. Incomplete combustion of organic compounds produces significantly harmful wastes such as Carbon soot and Carbon Monoxide. These wastes can cause and worsen asthma and cause even more health hazards. Even under complete combustion, Carbon Dioxide is produced. It is a greenhouse gas and is increasing at an alarming rate. As compared to 1990, carbon emissions have increased by more than 35% till date. The diagram on the left shows approximately how much and where the remaining crude oil is stored in the earth.
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Forming Bonds When a metal reacts with a non-metal, ions are formed. Metal atoms lose one or more electrons to form positively charged ions. Non-metal atoms gain electrons to form negatively charged ions. The oppositely charged ions attract each other strongly and the compound has ionic bonds. When non-metals combine, their atoms share electrons to form covalent bonds and molecules are formed. The formula of a molecule shows the number of atoms in the molecule; for example, H2O shows that a water molecule contains two hydrogen atoms and one oxygen atom.
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Geologists and scientist try and travel through time to see how old the earth is. Ways can be like checking rocks and seeing how old they are, the stripes of rocks, layers of rocks are visible, the landscape made of layers. The minerals, salts and mud in the sea also give us an idea of the age of the earth. Also you can find the age of the earth by digging up through tunnels and the mines underground. You can tell the age of rocks by their stripes, layers and other things that may be visible The earth hasn?t been created like the one the bible has said, it states that the earth was made
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