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Chemistry 1

Chemistry 1. Atoms and the periodic table Equations Limestone Metals Alkenes & alkanes Fractional distillation Polymers Vegetable oils Alternative fuels Plate tectonics Atmosphere. Atoms and the Periodic Table. Structure of the Atom. Shell. e. N eutron. N o charge. +. +.

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Chemistry 1

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  1. Chemistry 1 Atoms and the periodic table Equations Limestone Metals Alkenes & alkanes Fractional distillation Polymers Vegetable oils Alternative fuels Plate tectonics Atmosphere

  2. Atoms and the Periodic Table

  3. Structure of the Atom Shell e Neutron No charge + + Nucleus Proton Positive charge e Negative charge Electron

  4. Atoms • Nucleus has neutrons (neutral) & protons (positive) • Electrons orbit outside • Number of protons = number of electrons (so atom is neutral) M X A Atomic MASS (neutrons + protons) Element symbol Atomic NUMBER (protons)

  5. Electrons • Number of protons = Number of electrons(bottom number on data sheet) • Electrons are arranged in SHELLS 1st shell holds up to 2 electrons The other shells hold up to 8 electrons

  6. Electrons and Reactivity • Elements in the same GROUP have the same number of electrons in their outer shell, this makes them react in the same way. • Group 0 (Noble Gases) have FULL shells so they are UNREACTIVE. • Elements react to make their outer shells full they TRANSFER or SHARE electrons.

  7. Electrons and bonding e • Ionic Bonding • Metal+ Non-metal • TRANSFER electrons • Left Lose electrons (+ IONS) • All metals LOSE electrons • They give their electrons to the non metals (- IONS) • Opposite charges attract each other

  8. Electrons and bonding • Covalent Bonding • Non-metal+ Non-metal • SHARE pairs of electrons • Atoms are attracted to the electrons in the middle • Covalent bonds are shown as • H-H (single bond), • O=C=O (double bonds) e e

  9. Equations

  10. Chemical Equations • A + B  C + D • ReactantsProducts • Mass of reactants =Mass of products • Number of atoms of each element needs to be the same on each side of the equation

  11. hydrogen + oxygen  water • H2 + O2 H2O • Need to double oxygen on the product side, so 2 lots of water made; • H2 + O2 2H2O • Now there aren’t enough H atoms on the reactant side, so we need to double the hydrogen atoms; • 2H2 + O2 2H2O Balanced!

  12. The ones you need to know! • 2H2 + O2 2H2O • CaCO3 CaO + CO2 • 2Na + Cl2  2NaCl • 2Na + 2H2O  2NaOH + H2

  13. Reacting Masses • Calcium  calcium + carbon • carbonate oxide dioxide • Mass of reactants = Mass of products • After 100g calcium carbonate is heated for 10 minutes, 56g of calcium oxide is left over. How much carbon dioxide is given off? • Mass of reactants = Mass of products • 100g = 56g + ? • 100g - 56 = 44g

  14. Limestone

  15. Thermal decomposition of Limestone • Heating Limestone makes it break down O O Ca Ca C O C O O O

  16. The Limestone cycle Calcium carbonate O Ca C O O O C Carbon dioxide O Heat Carbon dioxide Ca O Lime-water Calcium oxide O C O Dissolve Water Ca H H O O Calcium hydroxide

  17. The Lime Kiln Waste gases (CO2 & N2) Waste gases also contains NITROGEN from the air. Methane & air • Calcium carbonate  calcium oxide + carbon dioxide • (thermal decomposition of limestone) • 2) Methane + oxygen  carbon dioxide + water vapour (combustion to heat the kiln)

  18. Testing for Carbon dioxide Limewater (calcium hydroxide) goes cloudy with CO2 Calcium carbonate is formed Carbonate Calcium + carbon dioxide  calcium + water hydroxidecarbonate Ca(OH)2+ CO2CaCO3+H2O (most metal carbonates except potassium will decompose)

  19. Acid Rain Limestone is ERODED by acid rain (giving off carbon dioxide) Calcium carbonate + hydrochloric acid  calcium chloride + carbon dioxide + water. CaCO3 + 2HCl  CaCl2 + H2O + CO2 It is also used to NEUTRALISEacidic soil.

  20. Uses of Limestone

  21. Uses of Limestone • Limestone Blockscarved into blocks and used to carve statues. • Mortar= calcium hydroxide. It sets by reacting with CO2 from the air (used to stick the limestone blocks of the pyramids together! • Cement(Calcium hydroxide + clay+sand) sets better than mortar, less crumbly. • Concrete =cement+ crushed rocks(aggregate) • NEUTRALISESacid soil.

  22. Quarrying

  23. Metals

  24. Potassium Sodium Calcium Magnesium Aluminium Carbon Zinc Iron Tin Lead Copper Silver Gold Platinum • The way we extract a metal depends on its place in the reactivity series Most reactive electrolysis reduction by carbon native Least reactive

  25. Native Metals • The most unreactive metals do not react, these ELEMENTS are found in the earth as metal nuggets.

  26. Ores • Other metals are found in the earth as COMPOUNDS. We need to use chemistry to extract the metal from the compound. • A rock that contains enough of a metal compound to make it worthwhile extracting is called an ORE. • This changes depending on the DEMAND for the metal.

  27. Iron and the Blast Furnace Ironoxide + carbon carbondioxide + iron This is a REDUCTION reaction Limestoneis added to remove impurities it makes SLAG

  28. Steel • Pig Iron from the blast furnace is too BRITTLE it breaks too easily. • Steel is an ALLOY of iron and carbon (and other elements) It is very STRONG.

  29. Iron & Steel Pig Iron from the blast furnace (4% carbon) Pure Iron (no carbon) Steel (1-2% carbon and other elements)

  30. Aluminium Positive ions are attracted to the negative electrode Al3+ • Aluminium is MORE reactive than carbon. • It cannot be reduced with carbon, it needs ELECTROLYSIS. • Impurities are removed from the ORE, then it is MELTED before electrolysis. • EXPENSIVE because it uses lots of energy) + - Aluminium

  31. Titanium • It is DISPLACED from its ore with a more reactive metal in a 2 step process. • Expensive • Titanium ore reacted with chlorine, then, • Sodium or magnesium displaces titanium • Magnesium chloride is made as a by product it is recycled (by electrolysis) • Lots of energy needed

  32. Alloys Ametalmixedwith other elements 18 carat gold: Gold&copper&silver (CHEAPERandSTRONGERthan pure gold)

  33. Copper • Main ORE is copper sulfide, it is used for wiring and water pipes, as it is not very reactive. • It is SMELTED using carbon It gives off SULFUR DIOXIDE (acid rain.) It is purified by electrolysis • Or it can be LEACHEDfrom rocks using sulfuric acid, the LEACHATE can be extracted by electrolysis OR using scrap metal

  34. Purifying Copper (electrolysis)

  35. Scrap Metal Scrap iron can be used to DISPLACE copper CHEAP, low energy costs, and uses cheap scrap metal

  36. Phytomining ASHES Burn Copper ions from low grade ore

  37. Bioleaching • BACTERIA feed on low grade ore and turn it into LEACHATE • Copper removed using scrap metal • Cheap, low energy costs • Takes a long time Mmm Rocks, om nom nom!

  38. Recycling • Metal ores are not renewable so we need to use them SUSTAINABLY

  39. Alkenes & Alkanes

  40. Hydrocarbons • Compounds made up of carbon and hydrogen atoms only • When they burn they produce carbon dioxideand water vapour

  41. Pollution Problems • Carbon dioxide = GLOBAL WARMING • Soot = GLOBAL DIMMING • Fossil fuels contain HYDROGEN SULFIDE • When they are burnt this releases SULFUR DIOXIDE this dissolves in the rain to make sulfuric acid ACID RAIN • NITROGEN OXIDES are made in hot engines when nitrogen in the air react with oxygen (ACID RAIN)

  42. Pollution Solutions • Acid Rain: • Remove hydrogen sulfide from fuels (useful by product) • Fit chimneys with limestone SCRUBBERS(removes sulfur dioxide) • Fit cars with CATALYTIC CONVERTERS (removes nitrogen oxides)

  43. Alkanes CnH2n+2 Single saturated Methane CH4 Ethane C2H6 Propane C3H8 Butane C4H10 Remember: Monkeys Eat Peanut Butter

  44. Alkenes CnH2n Unsaturated double Ethene C2H4 Propene C3H6 Alkenes DECOLOURISE bromine water e for equals!

  45. Properties of Hydrocarbons Boiling Point Volatility Viscosity sticky runny Flammability sooty

  46. Fractional Distillation

  47. Fractional Distillation

  48. How it works • Different FRACTIONS have different BOILING POINTS, so crude oil can be separated by FRACTIONAL DISTILLATION. • Heat crude oil • It boils and evaporates • Hot gases rise • Vapourcools • It condenses • It is collected • (Each fraction has a boiling RANGE as it is a MIXTURE of compounds with similar boiling points)

  49. Cracking • Most of crude oil is useless long chain hydrocarbons. • Cracking breaks long chains into more useful shorter chains. • One product is an alkene (decolourises bromine) • The other product is an alkane (doesn’t react with bromine) 800ºC + catalyst

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