C5

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  • C5- Chemicals in nature
    • Bonding in gases
      • (When heated)
        • The force between molecules (inter molecular bonds) but the bonds inside a molecule aren't (intra)
      • There are strong bonds holding atoms together in a molecule but weak forces between molecules
      • Mr= relative molecular mass ( the weight of a particular atom
      • All compared to carbon -12 which has the atomic mass of 12
    • Atom in molecules
      • There are forces of attraction between electrons and nucleus of other atoms.
        • Form molecules which are held together by attractions between the nuclei and shared by electrons.
          • This is a single covalent bond
            • Low melting point
    • Properties of salts
      • Salt has high melting and boiling points
        • It has very strong bonds between atoms
      • Salt crystals don't conduct electricity because electrons are too tight.
      • When sodium loses an electron and chlorine gains one.
        • Sodium chloride can come from Water evaporating from rock sediment leaving salt behind
      • Sodium chloride solution conducts electricity because the solution frees the electrons and allows more movement
    • Precipitates in solutions
      • A solid made during a chemical reaction from a liquid
    • Cations in solids
      • Cations are positive and anions are negative.
      • Add  dilute sodium hydroxide to test for precipitate
    • Silicon dioxide
      • Quartz is a form of SiO2 it contains silicon and oxygen
      • Has high m.p
      • Non metal
      • Not soluble in water
      • Hard crystalline structure
        • Giant ionic structures
          • Metal and non metal
          • Electrical conductor in solution or molten
    • Giant ionic structures
      • Metal and non metal
      • Electrical conductor in solution or molten
    • Diamond andgraphite
      • Covalent bonds join each carbon in graphite to 3 other carbon atoms
        • This makes flat sheets of hexagons made up of billions of atoms
        • Electrons move freely in gaps between layers and bond the layers weekly
          • This is why graphite conducts electricity
      • Covalent bonds join each carbon atom to its 4 nearest neighbours
        • Diamond does not conduct electricity even if molten because it has no electron particles free to move
      • High melting and boiling points
    • If a chemical gains oxygen then it is oxidised
      • If a chemical loses oxygen then it is reduced
    • Formula mass and percentage yields
      • Using the top number
      • (Actual yield/ theoretical yield)x100
    • Electrolysis
      • Splitting a chemical into elements by passing an electric current through it
        • Gas produced at positive electrode
      • Electrode
        • A conductor made of a metal or graphite through which a current enters or leaves a chemical during elecrolysis
      • Electrolyte
        • A chemical that can be split up by an electric current when molten or in solution ionic compounds are electrolyes
    • Metallic bonding
      • Mine the ore
        • Crush the ore
          • Purify the mineral by removing the impurities from the crushed ore.
            • Extract the metal from the mineral
              • Make the products from the metal
                • Use the product
    • Aluminium
      • Uses 4 tonnes bauxite ore,uses 15000kWh electricity and produces 9.6 tonnes CO2
      • Production causes dust production, makes hazardous/ toxic ponds, harmful chemicals escape
      • To make aluminium from recycling it uses 750kWh electricity and froduces 0.48 tonnes of O2

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