Chemistry C1

Atoms, elements and compounds:All substances are made of atomsElements are made of only one type of atomChemical symbols are used to represent atomsCompounds contain more than more elementAtomic structure:Nucleus of an atom is mad of protons and neutronsProtons have positive charge, electrons a negative charge and neutrons not chargedAtomic number or proton number is equal to the number of protons in the nucleus of its atomsElements are arranged in order of their atomic number in the perodic tablemass number is the sum of the protons and neutrons in the nucleus of an atomArrangment of electronsAtoms of unreactive noble gases all have very stable arrangements of electronsElectrons in atoms are in energy levels that can be represented by shells Electrons in the lowest energy level are in the shell closest to the nucleusElectrons occupy the lowest levels firstAll the elements in the same group of the perodic table have the same number of electrons in their highest energy levelForming Bondscompounds of metals bonded ton non-metals have ionic bondsThe formula of an ionic compounds shows the simplest ratio of ionsCompounds of non-metals have covalent bondsFormula of a molecule shows the number of atoms in the molecule

Limestone and it's  uses:Mainly made of carbon carbonateUsed as a building material and to make cement and calcuim oxideCement mixed with sand, aggregate and water makes concreteCalcuim carbonate decomposes when heated to make calcium oxide and carbon dioxideReactions of carbonatesMetal carbonates decompose when heated to produce metal oxide and carbon dioxidecarbonates react with acids to produce a salt,water and carbon dioxidecarbon dioxide turns limewater cloudyThe limestone reaction cycleThermal decomposition of calcuim carbonate produces calcuim oxide and carbon dioxidecalcuim oxide reacts with water to produce calcium hydroxideCalcuim hydroxide is an alkali that can be used to neutralise acidscalcium hydroxide reacts with carbon dioxide to produce calcium carbonateCement and concretecement is made by heating limestone with clay in a kilnMortar is made by mixing cement and sand with waterconcrete is made by mixing aggregate with cement, sand and waterLimestone issuesThere are good and bad points about quarrying for limestoneLimestone, cement and concrete are needed as building materialsquarrying and processing limestone and it products have negative impacts on it's environment: dust and noise, more traffic, loss of habitats for wildlife, more customers and trade for local businesses, improved roads

Extracting metals:Usually found in earth's crust, often chemically combined with other elements such as oxygenOre contains enough metal to make it worth extracting the metalUnreactive metals are found in the Earth as the metalOxides of metals less reactive than carbon can be reduced using carbonIron and steels:Iron oxide is reduced in a blast furnace to make iron, but is too brittle for many uses, many irons converted into alloys called steels which contains carefully controlled quantities of carbon and other elementsAuminium and titanium:They both resist corrosion and have low densities when compared to other metals, both cannot be extracted by reduction both expensive because extracting involves many stages and requires large amounts of energyExtracting copper:Most copper is extracted from copper rich ores by smeltingCopper an be purified by electroloysisBioleaching and phytomining are new ways to extract copper from low grade oresCopper can be obtained from solutions of copper salts by displacement or electrolysisUseful metals:Transition metals are found in the central block of the periodic tableHave properties that make them sutiable fro building and making things: good conductors of heat and electricity, strong but can be bent into shapeMost of the metals we use are alloysMetallic issuesthere are social, economic and environmental issues associated with exploiting metal oresRecycling saves energy and limited resourcesDrawbacks: obtaining ores causes pollution and uses limited resources, more expensive than other materials, iron and steel can rustBenefits: They are strong, easily bent into shape (malleable), can be made into flexible wires (ductile) and good eletrical conductors

Fuels from crude oil:Mixture of different compoundsDistillation can be used to seperate mixture of liquidsMost compounds in crude oil are hydrocarbons- they contain only hydrogen and carbonAlkanes are saturated hydrocarbons as they contain as many hydrogen atoms as possible in their moleculesCnH2n+2  general formulaFractional distallation:Crude oil is separated into fractions using fractional distillationThe properties of each fraction depend on the size of the hydrocarbon moleculesFractions with lower boiling points are less viscous(thick) and burn more easily (flammable)Burning fuels:Burning hydrocarbons in plenty of air produces carbon dioxideWhile burning hydrocarbons in a limited supply of air produces carbon monoxideAny sulfur compounds in fuel burn to make sulfur dioxide which makes acid rainOxides in nitrogen can be formed when fuels burn under extreme conditionsCleaner fuelsCarbon dioxide causes global warming , many scientists believeParticulates cause global dimmingSulfur and nitrogen oxides cause acid rainPollutants can be removed from waste gases after the fuel is burnedSulfur can be removed from fuels before they are burned so less sulfur dioxide is given offAlternative fuelsBiodiesel can be made from vegetable oilsBiofuel are a renewable source of energy that could be used instead of fossil fuelsAdvantages: contributes little to carbon dioxide levels carbon neutralDisadvantages; growing use large areas of farmlandEthanol made from sugar is a biofuelHydrogen is a potential fuel for the future

Cracking hydrocarbons:Hydrocarbon molecules can be broken down by heating them with steam to very high temperatures or by passing their vapours over a hot catalyst ( a substance that speeds up a chemical reaction. At the end of the reaction the catalyst remains chemically unchanged.)Cracking produces alkenes and alkanesAlkenes are unsaturated hydrocarbons and tun bromine water from orange to coloulessMaking polymers from alkenes:Plastics are made of polymersThey are large molecules made when many small molecules (monomers) join togetherAlkenes can be used to make polymer such as poly(ethene) and poly(propene)New and useful polymers:New polymerws are being developed all the timePolymers are designed to have properties that make them specially suited for certain uses: smart polymer is material used for stitching wounds that change shape when heated to body temperaturePlastic waste:Non-biodegradable plastics cause waste, can harm wildlife and consume space in landfill sitesBiodegradable plastics are decomposed by the action of microorganisms in soilMaking plastics with starch granules in their structure helps the microorganisms break down a plastic, can be made from plan material such as cornstarchEthanolCan be made by fermenting sugar using enzymes in yeastCan also be made by hydration of ethene with steam in the presence of a catalyst, this process needs non-renewable crude oil whereas as fermentation uses renewable plant materialPlant OilsExtracting vegetable oilsVegetable oils can be extracted from seeds, nuts and fruits by pressing or by distillationVegetable oils provide nutrients and a lot of energy, they are important foods and can be used to make biofuelsUnsaturated oils contain C=C as so they decolourise bromine waterCooking with vegetable oilsVegetable oils are useful in cooking because of their high burning pointsCooking in oil increases the energy content of foods and changes the flavor, colour and texture of the foodVegetable oils can be hardened by reacting them with hydrogen at 60c, as it makes them solids at room temperature which are suitable for spreadingEveryday emulsionsOils do not dissolve in water but these two things can be used to produce emulsions which have special properties:opague and thick improves texture, appearance and their ability to coat and stick to solidsEmulsions made from vegetable oil are used for many foods: milk; cream; salad dressing; and, ice creamHave molecules in which one part is hydrophilic and other hydrophobicFood issues:Vegetable oils are high in energy and provide nutrients, believed to better for health than saturated fatsEmulsifiers improve texture of foods enabling water and oil to mix, this makes fatty foods more palatable and tempting to eatOur Changing PlanetStructure of the EarthEarth is made of layers called the core, mantle and crust with the atmosphere around the outsideEarth's limited resources come from it's crust, the oceans and the atmosphereThe restless EarthEarth's crust and upper mantle is cracked into tectonic plates which are constantly moving, these moves because of convection currents in the mantle  that are caused by radioactive decay in the coreEarthquakes and volcanoes happen when tectonic plates meet, but is difficult to accurately predict when and where earthquakes will happenWagener's theory of continental drift was not accepted for yearsEarth's atmosphere in the pastEarth's early atmosphere was formed by volcanic activityProbably mainly consisted of carbon dioxide must have also been water vapour together with traces of methane and ammoniaAs plants spread over the Earth, the levels of oxygen in the atmosphere increasedLife on EarthMany theories of how life on earth started: compounds needed came from reactions involving hydrocarbons and ammonia when lightning provided energyAll the theories about how life started on Earth are unproven and so we cannot be sure how life beganGases in the atmosphereMost of the carbon dioxide in the early atmosphere became locked up in sedimentary rocksAbout four-fifths almost 80% is nitrogen and about a fifth is oxygen 21%Main gases in the air can be separated by fractional distillation these gases are used in industry as raw materialsCarbon dioxide in the atmosphere:Carbon moves into and out of the atmosphere due to plants, animals the oceans and rocksAmount of carbon dioxide in the Earth's atmosphere has risen in the recent past largely due to the amount fossil fuels we now burn

Fundematal ideas

Rocks and building Materials

Metals and their uses

Crude oil and fuels

Products from oil