- Created by: EstherTheBunny
- Created on: 13-06-12 23:21
Fundamental Ideas- 1
1.1 - 1.
- Element- made up of one type of atom.
- Compound- 2 or more atoms chemically joined together.
- Atoms- about 100 types in the periodic table, which is divided into metals and non-metals.
- Atoms- made up of a nucleus (which is made of neutrons and protons), and electrons. Mass number=bigger number on the symbol on the periodic table. Proton number= number below the mass number. Electron number=proton number. Neutron number= mass number minus proton number.
- Electrons- negatively charged. Protons- positively charged. Neutrons- neutrally charged.
- Each electron in an atom is on an energy level-electron shell. Only a certain maximum is allowed on each shell- 2, 8, 8, 18. Sodium has 11 electrons, so the electronic structure is 2, 8, 1.
- Ionic bonds-when a metal reacts with a non-metal, ions are formed. Metals lose 1 or more electrons and become positively charged ions. Non-metals gain 1 or more electrons and become negatively charged. Bother have full outer shells. However overall charge of the compound is neutral-zero.
- Covalent bonds- when non-metals react, they share electrons to gain full outer shells, and molecules are formed. Covalent bonds can be shown with lines. Water- H2O: outer shells: O: 6 electrons, needs 2 for a full shell. H: 1 electrons, needs 1 more for a full outershell. Therefore, two hydrogen atoms share their electron with oxygen and vice versa, so hydrogen get a full outer shell, and oxygen has the 2 it needed for a full shell.
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Rocks and Building Materials- 1
2.1 - 2.4
- Limestone cycle:
1 -CaCO3-->CaO+CO2 Calcium carbonate thermally decomposes into calcium oxide and carbon dioxide~ limestome-->
2-CaO+H2O-->Ca(OH)2 Calcium oxide + some water --> calcium hydroxide.
3 -Ca(OH)2+H2O-->Ca(OH)2(ag) Calcium hydroxide + more water --> calcium hydroxide solution. ~Quicklime + water --> limewater.
4 -Ca(OH)2(ag)-->CaCO3 Calcium hydroxide solution + carbon dioxide --> calcium carbonate. ~Limewater +CO2-->limestone.
- Limewater- used as a test for carbon dioxide-turns clody if it is CO2 positive.
- Calcium hydroxide-an alkali. Can react with acids in a nutralisation reaction to form a calcium salt and water. Used by farmers to improve acidic soil, raising the pH.
- Lime mortar- strongly heated limestone + water. Modern mortar- calcium hydroxide + water + sand. Used to hold building materials together
- Portland cement - limestone + clay + minerals, and then ground up into a fine powder.
- Concrete- aggregate + water + cement + sand. Very strong, good at resisting forces. Pouring it around steel irons/rods make reinforced concrete.
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Rocks and Building Materials- 2
- Quarrying- limestone is quarried from the dround, making a huge hole- the limestone is uually blasted by explosives, then taken in giant lorries to be processed.
- Pros: 1. Job opportunities. 2. Used as a landfill site afterwards. 3. Can be later filled with water, turned into a reservoir and used for leisure activities.
- Cons: 1. Noise pollution. 2. Harms wildlife. 3. Eyesore. 4. Dust affecting crops, etc.
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3.1 - 3.3
- Metals are found in the earth's crustin ores. An ore is a rock with enough of a metal compound in to make it economical to extract.
- Most metals need to be extraced, but those below hydrogen in the reactivity series need little or no extraction. Displacement can be used in electrolysis. Carbon can be used to reduce metals from their oxides.
- Blast furnace- where iron is extracted. Coke (carbon), Haematite (the ore of the Iron (III) oxide) and Limestone (removes impurities) are put into the furnace. 1. When heated, O2 in the air reacts with C from the coke to form CO2. 2. CO2 + C --> CO. 3. CO + FeO --> Fe + CO2. The metal produce has some impurities in making it hard and brittle, giving it few uses as just cast iron. Removing impurities creates pure iron but that is too soft for many uses.
- Most iron - used to make steels, which are alloys - mixtures of carbon, iron and other elements. Alloys can be made with different properties for specific uses. Stainless steel- corrosion-resistant.
- Aluminium- silvery & shiny, with a low density, and is also a very good conductor. It is easy to shape and draw into wires. It does not corrode easily- surface atoms react with O2 giving an aluminium oxide layer which stops corrosion. Extracted using electrolysis.
- Titanium- silvery white metal, very strong and corrosion-resistant due to an oxide layer. It has a very high melting point, used in replacement hip joints. Expensive to extract and take a long time.
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3.4 - 3.6
- Copper - smelting: copper ore is heated very strongly to make crude copper, purified by electrolysis.
- Copper - Electrolysis- adding sulphuric acid to produce copper sulphate solution, before extracting the copper. However, copper-rich ores are running out, scientists need to learn to extract from low-grade ores.
- Phytomining - plants are used to absorb copper compounds from the ground. Then they are burnt and copper is extracted from the ashes. Could be planted on **** heaps-waste from extraction of copper rich ores.
- Bioleaching - Bacteria feed on low-grade ores by different processes, and we get a solution of copper ions- 'leachate' from waste copper ore.
- Metals in the middle block of the periodic table-transition metals, mostly good conductors and strong.
- Metals in construction:
~Pros: -they are strong. -bent into shape -can be made into flexible wires. -good electrical conductors.
~Cons: -obtaining metals from ores causes pollution and uses resources. -metals are more expensive. -iron and steel can rust.
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Crude oil and fuels
4.1 - 4.5
- Crude oil- a mixture of different length chains of hydrocarbons.
- Crude oil- seperated by fractional distillation-different temperatures in the column are according to the boiling points of hydrocarbons.
- Methane: CH4 Ethane: C2H6 Propane: C3H8 Butane: C4H10 Pentane: C5H12. CnH2n+2.
- Alkanes- saturated fats. Alkenes: formula of CnH2n, unsaturated fats with a doubles bond in.
- Burning fuels are a process of combustion and incomplete combustion, both producing water. Incomplete combustion produces carbon monoxide when there isn't enough oxygen present. Complete- carbon dioxide produced.
- Incomplete combustion- soot, containing carbon and unburnt hydrocarbons-particulates-causes global dimming.
- Sulphur dioxide is also produced, which causes acid rain. So can nitrogen oxides.
- Producing carbon dioxide contributes to global warming.
- Biofuels-made from animal/plant products and are renewable. Biodiesel can be made from vegetable oils extracted from plants. It is carbon neutral. However, growing plants uses up space for growing food.
- Ethanol-can be made from sugar cane, and can be misxed with petrols. It saves using up dwindling crude oil supplies.
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Products from oil
5.1 - 5.4
- Large hydrocarbon molecules can be broken down into smaller molecules by cracking. This produces one alkene and at least one alkane. It can be done by: 1. heating hydrocarbon vapours and steam to a very high temperature. 2. passing hydrocarbon vapours over a hot catalyst. This is thermal decomposition.
- Alkenes react with bromine water turning it from orange to colourless.
- Alkenes are also known as monomers. They can be joined with many other monomers to make a polymer-polymerisation.
- Polymers are plastics, used as bags, bottles and containers.
- Smart polymers can be made with special properties. Hydrogels are polymers that can absorb a lot of water-like in nappies and dressings for wounds.
- Many polymers are not biodegradeable-the plastic doesn't break down when left in the environment.
- New biodegradeable plastics are being produced from plants such as cornstarch.
- Ethanol: C2H6O, but often written as C2H5OH to show it is an alcohol. It can be made my fermentation of sugar using yeast. Enzymes in the yeast cause sugar to convert to ethanol and CO2. It is renewable and done at room temperature. However, only a dilute aqueous solution is made-it has to be distilled further.
- It can also be made from the hydration of ethene (which has been made by cracking), by reacting ethene at a high temperature with a catalyst. The reaction can be run continuously, but uses a lot of energy.
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6.1 - 6.4
- Some seeds, nuts and fruits are rich in vegetable oils, extracted by pressing the plant material, and then removing the water and impurities.
- Some are extracted by distilling the plant material mixed with water, creating a mix of oil and water which can be seperated.
- Vegetable oils provide a lot of energy and good nutrients. They can also be used as fuels, and are used to make biofuels. They have hydrocarbon chains, and have double bonds so they are unsaturated. If there is more than one double bond in each molecule, they are called polyunsaturated fats.
- Boiling points of vegetable oil are higher than water, so food is cooked at higher temperatures, and cooks faster. Also, the colour and texture is change and it tastes nicer. Some oil is absorbed, increasing energy content of the food.
- Hydrogenation-hardening- unsaturated oils can be reacted with hydrogen to make saturated fats-alkanes. Conditions of 60 degrees celsius and a nickel catalyst is needed, and this makes the oils solid at room temperature.
- Oil and water are imiscible, and seperate gradually when mixed together, forming an emulsion. Emulsifiers can stable the emulsion, because they have a hydrophobic tail which is atttached to the oil droplet and a hydrophyllic head which is attached to the water. This improves texture, appearance and sticks to solids. However, they are high in fat, and saturated fats have been known to be linked to heart disease.
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Our Changing Planet- 1
7.1 - 7.3
- Structure of the Earth- almost spherical with a diameter if 12800km. It has a thin, solid crust varying in thickness rom 5km to 70km. The mantle under the crust is about 3000km thick, and is almost all solid but parts of it flow very slowly. The core is about half the diameter of Earth, with a lot of nickel and iron which are magnetic. It has a liquid outer part and a solid inner core. The atomosphere surrounds the planet, within 100km of the surface.
- Convectional currents: the crust is split up into pieces-tectonic plates which move due to convectional currents in the mantle due to radioactive processes in the core. It can cause volcanoes, earthquakes and create mountains.
- Alfred Wegener- he believed that the plates moved and that the continents fit together like a jigsaw piece. other scientists thought that the Earth was shrinking as it cooled.
- The earth was created about 4.5 billion years ago. At first the surface was covered with volcanoes releasing CO2, water vapour and nitrogen. As it cooled most of the vapour condensed to form oceans. Some scientists believe there was also methane and ammonia present at the time. In the next two billion years algae and plants evolved, using CO2 and releasing O2, increasing the amount of oxygen.
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Our Changing Planet- 2
7.4 - 7.6
- In 1952 Miller and Urey, 2 scientists did an experiment based on what was believed to be in the early atmosphere. A mixture of water, ammonia, methane and hydrogen used and a high voltage spark to simulate lightening. After a week amino acids (one of the building blocks for proteins) had been made.
- This mixture of gases in the atmosphere is known as the primordial soup.
- Today, the air is: -78% Nitrogen -21% Oxygen -0.9% Argon -0.04% CO2 and trace amounts of other gases.
- Seperating gases: 1. Liquefy the air at -200 degrees celsius 2. Feed it into a fractional distillation column. 3. Gaseous nitrogen is seperated, and further distillation is used to make pure oxygen and carbon. It is used in industry as raw materials.
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