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Revision for C1 C1 1 Fundamental ideas C1 2 Rocks and building materials C1 3 Metals and their uses C1 4 Crude oil and fuels C1 5 Products from oil C1 6 Plant oils C1 7 Our changing planet C1 1.1, 1.2 and 1.3 Atoms are made up of protons, neutrons and electrons. Nucleus Particle Charge Mass Proton +1 1 Neutron 0 1 Electron -1 0 Electrons are arranged in energy levels (shells). The fourth shell can hold 18 electrons (but you don’t The first shell can hold 2 need to go that far). electrons. The second shell can hold 8 electrons. Electron configurations can be written 2,8,8,18. The third shell can hold 8 electrons. All atoms want a full outer shell of electrons, and they will do that by gaining electrons, losing electrons or sharing electrons. C1 1.4 Forming bonds A metal atom gives electrons to a non-metal atom, so that both of them have full outer shells. When drawing the electron configuration for an ion, we draw square brackets around it, and put the charge on the outside. Electron configurations can be written Na [2,8]+ and Cl [2,8,8]- - + Na Cl We draw the electrons as different shapes to show which atom they came from (dot and cross diagrams) Charges on ions from different groups Group Outer shell electrons 1 1 2 2 3 3 4 4 Electrons gained/lost Loses 1 Loses 2 Loses 3 N/A Ion charge + 2+ 3+ N/A 5 5 6 6 7 7 Gains 3 Gains 2 Gains 1 3- 2- - 8 8 N/A N/A C1 1.4 Forming bonds If the positive and negative ions have different charges, then you will need different numbers of ions to balance out the charge e.g. MgF2. Mg F Remember: Swap n’ drop Swap the ion charge numbers, and drop them down to the bottom right of the element symbol. Get rid of the charge. These ions are on your data sheet, so you don’t need to remember them. Mg2+ MgF2 F- - 2+ F Compound ions If your compound has a compound ion (OH-, NO3-, SO42-, CO32-, NH4+) and there is more than one of them, you need to put it in brackets. E.G Mg(NO3)2, or (NH4)2O, or Al2(SO4)3 C1 1.4 Forming bonds Covalent bonding is a shared pair of electrons. Covalent bonding occurs between non metals. covalent bond F simplified dot and cross diagram solid line (one line = 1 pair) Group 4 elements share 4 electrons. Group 5 elements share 3 electrons. Group 6 elements share 2 electrons. Group 7 elements and hydrogen share 1 electron. F H F F N H O H H H F–F F –F H Cl O C O Balancing equations + + CH4 + 2O2 CO2 + 2H2O There are 4 hydrogens here. You multiply the big number by the little number. There are 4 hydrogens here, bonded together. There are 2 molecules of oxygen not bonded together. You can only change the BIG numbers in equations – we cannot change the small numbers or add or take away any reactants or products. C1 2.1 Limestone and its uses Carbon dioxide is formed from thermal decomposition of limestone and from burning methane. Argon and nitrogen come from the air. Calcium oxide Calcium carbonate CaCO3 CaO + Carbon dioxide CO2 Reaction of thermal decomposition limestone. Methane is fuel for the fire to heat limestone. C1 2.2 Reactions of carbonates CaCO3(s) CaO(s) + CO2(g) CaO(s) + H2O(l) Ca(OH)2(s) Ca(OH)2(s) Ca(OH)2(aq) Ca(OH)2(aq) + CO2(g) CaCO3(s) + H2O(l) Limestone is heated and breaks down (thermal decomposition) into calcium oxide (quicklime) and carbon dioxide. Calcium oxide (quicklime) is added to water to make solid calcium hydroxide (slaked lime). Solid calcium hydroxide (slaked lime) is dissolved in water to make aqueous calcium hydroxide (lime water). Aqueous calcium hydroxide (lime water) is added to carbon dioxide which makes calcium carbonate and water. C1 2.3 Limestone reaction cycle and C1 2.4 cement and concrete + Sand + Sand + Water + Gravel Concrete Cement + Clay + Limestone Water Mortar CaO Calcium Carbonate CaCO3 HEAT Calcium Oxide + + Water Calcium Hydroxide Limewater Ca(OH)2 Carbon Dioxide CO2 C1 2.5 Limestone issues Limestone quarrying has many advantages and disadvantages: Advantages It creates jobs It provides building materials nearby Disadvantages Pollution Noise pollution It ruins the landscape C1 3.1 Extraction of metals Extracted using electrolysis. Extracted using reduction by carbon. Found as elements (native). Reduction is a reaction that removes oxygen from the metal oxide. Carbon + oxygen Carbon dioxide C + O2 CO2 C1 3.2 Extraction of iron Carbon dioxide + carbon Carbon monoxide CO2 + C 2CO Iron oxide + carbon monoxide Iron + carbon dioxide Fe2O3 + 3CO 2Fe + 3CO2 Iron oxide + carbon Iron + carbon dioxide 2Fe2O3 + 3C 4Fe + 3CO2 The iron produced in the blast furnace is 4% carbon. This is called pig iron. Pure iron is arranged in layers . When an atom is struck, the whole layer moves. Pure iron is malleable. Pig iron is very brittle because the atoms are not in layers due to the carbon atoms disrupting the layers. Steel Low carbon steel High carbon steel Low alloy steels High alloy steels Stainless steels Tungsten steel Composition Uses Iron, carbon (0.1%) Cars, buildings and bridges Iron, carbon (1.5%) Tools, knives and swords Iron, carbon, Cars, trucks, manganese, nickel bridges Iron, carbon, Tools, armour chromium Iron, carbon, Cutlery, nickel, chromium saucepans, medical instruments. Iron, carbon, Drill bits tungsten Pure iron is arranged in layers . When an atom is struck, the whole layer moves. Pure iron is malleable. C1 3.2 Steels Steels are mixtures of iron, carbon and possibly other metals. Steels are alloys. Alloys are stronger than pure metals because they disrupt the layers of the metals and stop them sliding over each other. The layers of alloys are disrupted, so they stop the layers of metal atoms sliding over each other. C1 3.3 Aluminium and titanium Aluminium is too reactive to extract from its ore using carbon, so it is extracted using electrolysis. Aluminium is light and strong. It is used for aircraft, foil, drinks cans, saucepans and bicycles. Titanium is not reactive, but if carbon is used to displace it, it will form brittle titanium carbide. Instead, titanium oxide is reacted with chlorine to make titanium chloride. It is then reacted with sodium to make titanium. This is expensive as the sodium needs to be extracted using electrolysis. C1 3.4 Extraction of copper and C1 3.6 metallic issues. Copper sulphide + oxygen Copper + sulphur dioxide This is called smelting. Sulphur dioxide causes acid rain. The copper then undergoes electrolysis in order to purify it. Copper can also be extracted by phytomining. Plants take up copper from the soil. The plants are then burnt and the ashes are put in sulphuric acid. Scrap iron is added to the copper sulphate to displace it. Iron + copper sulphate Copper + iron sulphate Copper can also be extracted by bioleaching. Bacteria feed on copper ores to get copper solutions. These solutions are also reacted with iron to extract the copper. Iron + copper sulphate Copper + iron sulphate C1 chapter 3.5 Useful metals and C1 3.6 metallic issues. They have the following properties: Shiny Malleable Hard Strong High melting point Sonorous Conducts electricity Conducts heat It is good to recycle metals because it saves energy from extracting them. It reduces pollution as the vehicles are no longer needed to excavate them and it means that less ore is used up. C1 chapter 4.1 Crude oil Crude oil is a mixture of lots of different chemicals called alkanes. Alkanes only contain hydrogen and carbon (hydrocarbons) an they have all single bonds (they are saturated) and have a general formula of CnH2n+2. C1 4.1 Alkanes Shorter chain alkanes have: Longer chain alkanes have: Lower boiling points. Higher boiling points. Low viscosity. High viscosity. High flammability. Less flammability. C1 4.2 Fractional distillation In fractional distillation, crude oil is heated up. Smaller alkanes have lower boiling points and they go to the top. Larger alkanes have larger boiling points and they stay at the bottom. The crude oil is split into fractions. Each fraction has a use. C1 4.3 and C1 4.4 Burning fuels and Cleaner fuels. C1 4.5 Alternative fuels Biodiesel Biodiesel is fuel from plant or animal products, such as vegetable oils or animal waste. Ethanol Made by fermenting sugar from plants. Advantages Advantages • It burns cleanly. • It burns cleanly. • It is carbon neutral. • It is carbon neutral. Disadvantages • It is less harmful to plants and animals. • It needs land that should be used for Disadvantages food. • It needs land that should be • It destroys used for food. habitats. • It destroys habitats. Hydrogen Made from electrolysis of water. Advantages • It burns cleanly. • Obtained from water Disadvantages • Requires electricity. • Explosive. • Needs larger volume to store. C1 5.1 Cracking hydrocarbons Alkenes – Alkenes are hydrocarbons (made up of carbon and hydrogen) with a carbon-carbon double bond (C=C). They have the general formula CnH2n (2 hydrogens for every carbon). You can use bromine water to work out if you have an alkene. Bromine water is brown. Alkenes make it colourless. Alkanes do not change the colour (it stays brown). Cracking – this is when a large alkane is turned into a smaller alkane and an alkene. C1 5.2 Making polymers from alkenes If alkenes are put under a high temperature and pressure, then they all link up to form a long chain called a polymer. An individual alkene is called a monomer (mono = one, mer = part). When they are joined together, they become a polymer (poly = many) An individual unit is in square brackets. The lines show that it is bonded to monomers outside the brackets. n = a big number C1 5.3 New and useful polymers Hydrogels are polymers that can trap water inside them. They can be used as contact lenses or dressings for burns. Stitches can be made from shape memory polymers which tighten to just the right tightness to close a wound. Eventually, when the wound is healed, they dissolve away. Plasters can be made from light sensitive polymers that lose their stickiness when exposed to light. Instead of ripping the plaster off, you can just rip the cover off which makes the plaster fall away. C1 5.4 Plastic waste Landfill Advantages Easy Relatively cheap Quick Disadvantages Uses up land The plastics stay for centuries Incineration Recycling Biodegradable plastics Quick Saves energy and Saves landfill The plastics can resources. space. be used as fuel. Preserves crude oil supplies. Tropical forests are destroyed to create farm land. Causes Takes time and Needs land space pollution fuel (to transport to grow crops and sort). (reduces land Recycled plastic is space to grow never as strong as food) original plastic. C1 5.5 Ethanol Ethanol can be made by fermentation yeast Sugar (glucose) Ethanol + carbon dioxide C6H12O6 2C2H5OH + 2 CO2 Sugar is a renewable resource, but it needs land to grow, which would take away land needed to grow food. Ethanol can also be made by hydration (Adding water to) ethene. Phosphoric acid catalyst Ethene + steam C2H4 + H2O Ethanol C2H5OH Ethene is from crude oil, so this method is non renewable. It does produce pure ethanol, however. Ethanol can be used as a fuel or a solvent. C1 6.1 Extracting vegatable oil Plants use energy from the sun to make glucose. They then turn this glucose into other chemicals, such as vegetable oil. Chlorophyll Carbon dioxide + water 6CO2 Sunlight Glucose + oxygen C6H12O6 + 6O2 + 6H2O Vegatable oils are unsaturated (they have carbon-carbon double bonds). Animal fats are saturated (they have no double bonds). Vegatable oils are liquids at room temperature. Animal fats are solids at room temperature. Animal fat Vegetable oil Animal fat Vegetable oil C1 6.2 Cooking with vegetable oils Cooking things in oil (compared to cooking things in water) cooks them more quickly (because oil has a higher boiling point), makes the outside of the food change colour and crispier, and makes the inside softer. vs Cooking in water. Cooking in oil. Foods cooked in oil have more energy than foods cooked in water. Hydrogenation of vegetable oils Hardened vegetable oil Unsaturated vegetable oil H C H C H H C H C H Nickel +H H 60oC C1 6.3 Everyday emulsions When water and oil mix, little droplets of oil form in the water. This mixture is called an emulsion. We use emulsifiers to help oil and water mix. Emulsifiers have two parts –a head that mixes with water (hydrophilic) and a tail that mixes with oil (hydrophobic). However, water and oil do not mix easily (they are immiscible), so they end up like this. This is how emulsifiers help oil and water mix. Oil Emulsifiers can be used to help make mayonnaise and detergents to help wash up oily pans. Water C1 6.4 Food issues A food additive is a substance that is added to a food to improve its taste, preserve it or change its colour. All food additives in our food have an E number to prove that they have passed a safety standard. Emulsifiers have an E number that begins with 4. Emulsifers stop oil and water based substances from separating. Emulsifiers are needed in chocolate, mayonaise and ice cream. So emulsifers make foods with lots of energy easier to eat and so it is tempting to eat more fatty food. vs Vegetable oils are healthier than animal fats. They contain vitamin E and they are better for the heart than animal fats. C1 7.1 Structure of the Earth Atmosphere Crust About 100km from 5 – 70km thick the surface to the top. Mantle 3000km thick Core 3500km in diameter Made of 78% Made of rock. We get nitrogen, 21% oxygen, minerals from the 1% argon and 0.04% crust and the oceans. carbon dioxide. We collect the gases from the atmosphere to use. Semi liquid. It can flow very slowly. The crust floats on top of it. Made of iron and nickel. The outer part is liquid due to the high temperature and the inner part is solid due to the high pressure. We know what the inside of the earth is like from earthquake data. The way the earthquake waves bend tell us the density of the substances below the surface. C1 7.2 The restless Earth The Earth’s crust is split into sections called plates. The plate boundaries are where we find earthquakes, volcanoes and mountains. Mountains form when two plates move together. Earthquakes occur when two plates rub side by side. Plates move because they are floating on top of the semi-liquid mantle. Radioactive processes in the mantle release heat which make convection currents which make the plates move. Alfred Wegener came up with the theory of plate tectonics. His evidence was that fossils and rocks on different continents were similar, indicating that they were once joined. However, this was also supported by the idea of a land bridge which connected South America and Africa. His theories were not accepted until 50 years later when scientists discovered something called seafloor spreading. C1 7.3 The Earth’s atmosphere in the past 4 Billion years ago Earth’s atmosphere was mainly carbon dioxide, with methane, water vapour, nitrogen and ammonia. 4 billion years ago 3.4 Billion years ago The oceans are formed when water vapour condensed. Life was formed. It was bacteria that used undersea volcanoes as a source of food. 2.5 Billion years ago Algae evolved which could use photosynthesis to make food from gases in the atmosphere. 200 million years ago The Earth’s atmosphere is the same as what it is today. 600 million years ago 2.5 Billion years ago Animals evolved which could use the oxygen for respiration. The oxygen in the atmosphere reacts with the methane and the ammonia in the atmosphere. C1 7.4 Life on Earth The Miller-Urey experiment took place in 1953. The scientists took the substances that were in the atmosphere billions years ago. They used water, methane, ammonia and hydrogen and passed an electric spark through them. They got 11 amino acids. C1 7.5 Gases in the atmosphere Carbon dioxide has been ‘locked into’ rocks such as limestone. Ammonia and methane in the atmosphere reacted with oxygen to form carbon dioxide, water and nitrogen. CH4 + 2O2 CO2 + 2H2O 4NH3 + 3O2 2N2 + 6H2O The gases in the atmosphere can be removed by fractional distillation. The gases are cooled to a temperature below -200oC and gradually heated up. Nitrogen boils off first at -196oC. C1 7.6 Carbon dioxide in the atmosphere The carbon cycle issolves hotosynthesis Respirati on lants espiratio n nimals alcium arbonate Sedimentation Sedimentation imestone Since the 1960s, the amount of carbon dioxide in the atmosphere has increased. This may be due to burning fossil fuels. Some of the carbon dioxide is absorbed into the oceans. This makes them more acidic, which reacts with coral reefs.