Chemistry Unit One

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  • Chemistry Unit 1
    • Atoms and elements
      • Atoms
        • atoms have a small nucleus it contains protons (+) and neutrons (neutral)
        • Electrons surround the nucleus and are negatively charged
        • Atoms have no charge overall, the number of protons equals the number of electrons
      • elements
        • consists of only one type of atom
    • The Periodic Table
      • Atoms can be represented by symbols such as C = Carbon
      • The periodic table puts elements with similar properties together in the groups
    • Electron shells
      • only 2 electrons are allowed on the inner shell
        • 8 on all the others
      • All atoms want a full outer shell, some have to react to gain this
      • These shells are shown in electronic structures
    • Compounds
      • Atoms join together to make compounds
      • a formula shows what atoms are in a compound
    • Limestone
      • Mainly calcium carbonate
        • when heated it thermally decomposes to make calcium oxide and carbon dioxide
      • calcium oxide reacts with water to produce calcium hydroxide
        • when heated it thermally decomposes to make calcium oxide and carbon dioxide
        • This is used to neutralise acidic soil in fields and to test for carbon dioxide
      • heated with kiln to make cement
      • Quarrying limestone
        • noisy, and causes masses of dust
        • Destroys habitats
        • Pollution : transportation of limestone, cement factories, burning of fossil fuels
        • provides the materials to build houses, roads and chemicals
      • Advantages
        • cheaper than granite or marble
        • widely available
        • can neutralise sulphur dioxide
        • can give people jobs via quarrying
        • concrete doesn't corrode
    • Getting metals from rocks
      • Metals are extracted from their ores chemically
        • this is called electrolysis
          • copper is purified by electrolysis
          • electrolysis means splitting up with electricity
        • or reduction with carbon
      • disavantages
        • causes noise
        • destroys habitats and scars the landscape
        • deep mine shafts can be dangerous
      • advantages
        • useful products made
        • provides jobs and brings money into the area
      • Recycling metals are important
        • mining and extraction use up fossil fuels which are running out
        • energy doesnt come cheap
        • theres and finite amount of metals in the earth
        • cuts down the amount of rubbish in landfills
    • properties of metals
      • strong, bendy and good conductors
    • Alloys
      • pure iron tends to be a little too bendy, so is converted into steel, an alloy
      • alloys are harder than pure metal
    • Crude oil
      • Fractional distillation
        • crude oil is a mixture of hydrocarbon
        • each fraction contains molecules with a similar number of carbon atoms
        • the crude oil is split into the separate groups of hydrocarbons
        • the crude oil vaporised rises up the column and tap off at the different levels that they condense
      • properties and uses
        • mostly alkanes
        • the shorter the molecule the more runny
        • the shorter the molecule the more votile
        • the shorter the molecule the more flammable
      • using crude oil as a fuel
        • burns cleanly
        • non-renewable
        • environmentally damaging
          • oil spills, poisonous
          • global warming
          • global dimming
          • acid rain
      • cracking crude oil
        • means to split up long chains of hydrocarbons
        • passing vapour over a hot catalyst
    • Environment problems
      • burning fossil fuels releases gas and particles
        • carbon monoxide
        • sulphur dioxide
        • soot
      • sulphur dioxide causes acid rain when mixed with clouds it produces sulphuric acid
      • soot and ash cause global dimming, these particles reflect sunlight back into space
      • alternative fuels
        • ethanol
          • advantages
            • carbon neutral
          • disadvantages
            • engines have to be converted
            • isnt widely available
            • will increase food prices as made from food products
        • biodiesel
          • advantages
            • carbon neutral
            • engines dont need to be converted
            • produces less sulphur dioxide and particles
          • disadvantages
            • cannot make enough to completely replace diesel
            • expensive to make
            • will increase food prices
        • hydrogen gas
          • advantages
            • very clean
          • disadvantages
            • need special and expensive engines
            • isnt widely available
            • hard to store
    • Alkenes
      • have a double bond between two carbon atom
      • Cn H2n
      • can test for alkenes by adding it to bromide water, it will decolourise
      • using alkenes to make polymers
        • polymerisation, the joining of lots of small alkene molecules (monomers)
        • uses
          • plastic bags
          • waterproof coatings
          • elastic
          • memory foam
          • biodegradable packaging
        • theyre cheap, but are hard to get rid of because they dont rot
    • Plant oils
      • can extract by squashing the plant inbetween two metal plates
      • vegetable oils
        • used in foods, have a high content of energy
        • benefits for cooking such as higher boiling points, different flavour
        • can produce fuel
      • unsaturated oils contain a double C bond
      • unsaturated oils can be hydrogenated
    • emulsions
      • can be made from oil and water
      • emulsifiers stop emulsions from separating out
      • lower in fat
    • plate tectonic and earths structure
      • Wegners theory of continental drift
        • realised that fossils matched with certain countries
        • noticed that the countries matched together like a jigsaw
        • wasnt accepted due to his explanation not being convincing
      • Earths structure
        • crust, which we live on is very thin, surrounded by the atmosphere
        • mantle, contains radioactive decay, produces lots of heat which causes the mantle to flow in convection current
        • core, the centre of Earth consists of nickle and iron
      • the evolution of the atmosphere
        • volcanoes gave out gases, ocean formed by condensed water vapout
        • green plants evolved producing oxygen
        • an ozone layer allows evolution of complex animals

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