C5

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  • Created by: emchown
  • Created on: 10-03-15 16:38
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  • C5
    • Atmosphere
      • Layer of gas surrounding the earth
      • Made up of elements: Nitrogen, Oxygen, Argon, Carbon Dioxide and Water Vapour
      • Chemicals in the atmosphere consist of non-metal element and molecular compounds
      • Molecules that make up the atmosphere are gases because they have very low melting points.
        • Molecular compunds have strong covalent bonds between the atoms that make up the compound.
        • Only weak forces of attraction between the small molecules
          • Molecular compunds have strong covalent bonds between the atoms that make up the compound.
          • Small amounts of energy are needed to break these forces
      • Atoms within molecules (hydrogen) are connected by strong cobvalent bonds.
        • Covalents bonds - electrons are shared between the nuclei of 2 atoms.
          • Causes a strong, electrostatic attraction between nuclei and shared electrons
      • Unlike ionic compunds, pure molecular compunds dont conduct electricity - molecules arent charged.
    • Hydrosphere
      • All the water on the Earth. The water contains dissolved compounds.
      • Seawater is salty because it contains dissolved ionic compounds.
        • eg Sodium Chloride; Sodium Sulfate; Potassium Bromide.
      • The Water Molecule
        • Good solvent for salts.
        • Bent because electrons in covalent bond are nearer to oxygen atom than hydrogen atoms.
          • A Polar Molecule
        • Charges on atoms means forces between molecules are slightly stronger than any other.
          • More energy needed to seperate
        • Small charges help to dissolve ionic compounds as the water molecules attract ions.
    • Lithosphere
      • Rigid outer layer of Earth made from the crust and upper part of mantle
      • Mixture of minerals (silicon dioxide)
      • Abundant elements in it include Silicon, Oxygen and Aluminium
      • Silicon Dioxide
        • Giant Covalent structure
        • Each silicon atom is covakently bonded to 4 oxygen atoms.
        • Each oxgyen covalently bonded to 2 silicons.
        • Strong, rigid sturcture.
        • Doesnt conduct electricity - no ions or free electrons
        • Does dissolve in water - no charge to attract water molecules
        • High melting and boiling points
        • Exists in different forms
          • Quartz in Granite - main thing in Sandstone
          • Amethyst - used as gemstone, cut and polished for jewellery.
        • Used for Furnace Linings - high melting point, alot of energy to break bonds
      • Carbon
        • Giant Covalent Structure
        • Diamond
          • Large no. of covalent bonds - high melting and boiling point
          • Each carbon atom covalently bonded to 4 others.
          • Very strong, rigid, 3D structure - difficult to break down
          • Insoluble - no charges to attract water molecules
          • Doesnt conduct electricity - no ions or free electrons
          • Used as Drill Tips - very hard and alot of energy needed to break covalent bonds
        • Graphite
          • Giant covalent structure
          • Layered Structure
            • Slide past eachother - soft and slippery
          • Each carbon covalently bonded to 3 others
          • Insoluble - strong bonds
          • High melting and boiling points
          • Can conduct electricity - electrons forming weak bonds between layers are free to move.
          • Used in Pencils - soft, layers removed easy and stick to paper
    • Identification of Ions
      • Insoluble compounds will give precipitates - used to identify metal ions
      • Oceans - dissolved calcium and carbonate ions form precipitate Calcium Carbonate (limestone)
      • To identify a negtive ion, range of different test can be carried out
      • Adding a reagent  to  unknown sample which react with ions to form an in soluble salt
        • To identify a negtive ion, range of different test can be carried out
      • Sulfate Ions
        • Add barium chloride solution and dilute hydrochloric acid to sulfate solution
        • A white precipitate of barium sulfate will be produced if a sulfate is present
        • barium ion + sulfate ion = barium sulfate
      • Chloride, Bromide and Iodide Ions
        • Cream precipitate - silver bromide
        • White precipitate - silver chloride
        • To identify, add silver nitrate solution and nitric acid to suspected halide solution
        • Yellow precipitate - silver iodide
      • Most ionic compounds are soluble in water
    • Testing for Carbonates
      • Acids
        • Carbonates react with dilute acids to from carbon dioxide (and salt and water)
        • eg. add calcium carbonate to dilute hydrochloric acid, carbonate will fizz and give off CO2
        • calcium carbonate + hydrochloric acid = calcium chloride + carbon dioxide + water
      • Thermal Decomposition
        • Copper Carbonate and Zinc Carbonate heated - thermal decomposition reaction takes place
        • Results in distinctive colour change which enables two compounds to be identified
        • Heat copper carbonate (green) forms Copper Oxide (black)
        • Heat Zinc Carbonate (white) forms Zinc Oxide (yellow at  high temps.) Cools and returns whate.
    • Extracting Useful Materials (Lithosphere)
      • Naturally occurring elements and compounds are called Minerals
      • Ores are rocks that contain varying amounts of minerals of which metals and be extracted.
      • Method of extraction depends on the metals postition on the reactivity series
      • Metals above Carbon in the reactivity series are very reactive and have to be extracted by Electrolysis
      • Metals below Carbon are extracted by reduction (heating with Carbon or Carbon Monoxide)
      • All metals below hydrogen can be extracted using Hydrogen
      • Gold and Platinum are unreactive so are obtained by physical processes (panning)
      • Extraction by reduction with Carbon
        • Zinc extracted from Zinc Oxide by heating with carbon
        • Zinc oxide reduced because it loses oxygen
        • Carbon is oxidised because it gains oxygen
        • Zinc Oxide + Carbon = Zinc + Carbon Dioxide
    • Metals and the Environment
      • Life Cycle assessment of metal products must be carried out
      • Making Mineral from Raw Materials
        • Mining
          • Rock wasted
          • Scar on landscape
          • Air pollution
          • Noise pollution
        • Processing
          • Pollutants used by transportation
          • Energy usage
        • Extracting Metal
          • Electrolysis uses more energy than reduction
      • Making Product from Mineral
        • Energy usage in processing and transportation
      • Use
        • Transport
          • Pollutants
        • Running Product
          • Energy Usage
      • Disposal
        • Reuse
          • No impact
        • Recycle
          • Less energy than initial manufacturing
        • Throw Away
          • Landfill sites remove habitats and are unsightly
    • Extraction by Electrolysis
      • Decomposition of an electrolyte (solution that conducts electricity) using electric current
      • Ionic compounds will only conduct electricity when electrons are free to move (molten or dissolved in solution)
      • Electrostatic forces between charged ions broken down
      • Molten Lead Bromide
        • Contains positive lead ions and negative bromide ions
        • When current passed through the molten salt, postive lead ions sttracted towards negative electrode and negative bromide ions atrracted to positive electrode
        • Lead is formed at negative and Bromine to positive
        • When ions get to oppositely charged electrode, the are discharged.
        • Bromide ions lose electrons to positive electrode - bromine atom
        • Lead ions gain electrons from negative electrode - lead atom
      • Aluminium Ore
        • Too reactive to be extracted using carbon
        • Aluminium oxide mixed with Cryolite to lower melting point
        • Mixture melted
        • Aluminium ion move towards negative electrode - aluminium formed
        • Oxide ions attracted to positive electrode - oxygen formed
          • Positive electrodes burn away quickly and have to be replaced frequently.
        • Expensive process - large amounts of energy needed
        • Positive electrode
          • Al3+ + 3e- = Al
          • Reduction
        • Negative electrode
          • 2O2- - 4e- = O2
          • Oxidisation
    • Properties of Metals
      • Generally, metals are strong and malleable
      • Metal crystalline structure - positively charged metal ions are held close together by a sea of electrons that are free to move
      • Properties of a metal can be explained by its structure
      • Force of attraction that keeps structure together is called a Metallic Bond
      • Very Strong - metal ions closely packed together on a lattice structure
      • High Melting Point - A lot of energy needed to break strong force of attraction
      • Malleable - External forces cause layers of metal ions to move by sliding over other layers
      • Conducts Electricity - Electrons free to move throughout structure. Electrical force applied, the electrons move along the metal in one direction
  • Chloride, Bromide and Iodide Ions
    • Cream precipitate - silver bromide
    • White precipitate - silver chloride
    • To identify, add silver nitrate solution and nitric acid to suspected halide solution
    • Yellow precipitate - silver iodide

Comments

Lucyadams123

All the boxes are overlapped i cannot read them

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