AQA Science Chemistry key points

C3
C1 4.1-
1. Crude oils and fuels
C1 1.1- C1 3.6
1. Fundamental ideas
  1. C1 1.1
    1. All substances are made up of atoms
    2. Elements only contain one type of atom
    3. Compounds contain two or more types of atoms
    4. An atom Has a tine nucleus in its centre, surrounded by electrons
  2. C1 1.2
    1. Atoms are made of protons, neutrons and electrons
    2. Protons have equal and opposite electric charges
      1. protons are positively charged
      2. Electrons are negatively charged
      3. Neutrons have no electrical charge they are neutral
    3. Atomic number
      1. Number of protons plus neutrons
    4. Atoms are arranged in the periodic table in order of there atomic number
  3. C1 1.3
    1. The electrons in an atom are arranged in energy levels or shells
    2. Atoms with the same number of electrons in there outer shell belong in the same group of the periodic table
      1. Group 1 alkaline metals
      2. Group 7 halogens
      3. Group 0 noble gases
        all have a very stable arrangement of electrons
    3. The number of electrons in the outermost shell of an element's atoms determines the way that element reacts
  4. C1 1.5
    1. As no new atoms ever created or destroyed in a chemical reaction
      1. The total mass of reactants = the total mass of production
    2. There is the same number of each type of atom on each side of a balanced symbol equation
  5. C1 1.4
    1. When atoms from different elements react together they make compounds
      1. The formula of a compound shows the number and type of atoms that have bonded together to make that compound
    2. When metals react with non-metals, charged particles called ions are formed
    3. Metal atoms form positively charged ions.
      1. Non-metals form negatively charged ions.
        These oppositely charged ions attract each other in ionic bonding
    4. Atoms of non-metals bond to each other by sharing electrons
      1. This is called covalent bonding
2. Rocks and building materials
  1. C1 2.1
    1. Limestone is made mainly of calcium carbonate
    2. Limestone is widely used in the building industry
    3. The calcium carbonate in limestone breaks down when we heat it strongly to make calcium oxide
  2. C1 2.3
    1. when water is added to calcium oxide it produces calcium hydroxide
    2. Calcium hydroxide is alkaline so it can be used to neutralise acids
    3. The reactions of limestone and its products that you need to know are shown in the " Limestone reaction cycle"
  3. C1 2.2
    1. Carbonates react with dilute acid to form a salt, water and carbon dioxide
    2. Limewater turns cloudy in the test for carbon dioxide gas
      1. A precipitate of insoluble calcium carbonate causes the cloudiness
    3. Metal carbonates decompose on heating to form the metal oxide and carbon dioxide
  4. C1 2.4
    1. Cement is made by heating limestone with clay in a kiln
    2. Mortar is made by mixing cement and sand with water
    3. Concrete is made by mixing crushed rocks or small stones called aggregate, cement and sand with water
  5. C1 2.5
    1. There are good and bad points about quarrying for limestone
      1. For example, more jobs will be created but there will be a large scare on the landscape
    2. Limestone, cement and concrete all have useful properties for use as building materials but the mining and processing of limestone and its products gas a major effect on our environment
3. metals and their uses
  1. C1 3.2
    1. Pure iron is too soft for it to be very usful
    2. We extract iron from iron ore by reduction it using carbon in a blast furnace
    3. Carefully controlled quantities of carbon an other elements are added to iron to make alloys of steel with different properties
    4. Important examples of steels are
      1. Low carbon steels which are easily shaped
      2. High carbon steels which are very hard
      3. Stainless steels which are resistant to corrosion
  2. C1 3.1
    1. A metal ore contains enough of the metal to make it economic to extract the metal
      1. Ores are mined and might need to be concentrated before the metal is extracted and purified
    2. We can find gold and other unreactive metals in their native state
    3. The reactivity series helps us decide the best way to extract a metal from its ore
      1. The oxides of metals below carbon in the series can be reduced by carbon to give the metal element
    4. Metals more reactive than carbon cannot be extracted from their ores using carbon
  3. C1 3.3
    1. Aluminium and titanium are useful because they resist corrosion
    2. Aluminium requires the electrolysis of molten aluminium oxide to extract it as it is too reactive to reduce using carbon
    3. Aluminium and titanium are expensive because extracting them from their ores involves many stages and requires large amounts of energy
  4. C1 3.4
    1. Most copper is extracted by smelting copper rich ores, although our limited supplies of ores are becoming more scarce
    2. Scientists are developing ways to extract copper that use low-grade copper ores
      1. Bacteria are used in bioleaching and plants in phytomining
  5. C1 3.4
    1. Most copper is extracted by smelting copper ores, although our limited supplies of ores are becoming more scarce
    2. Copper can be extracted from copper solutions by electrolysis or by displacement using scrap iron
      1. Electrolysis is also used to purify copper
  6. C1 3.5
    1. The transition metals are found in the central block of elements in the periodic table
    2. Transition metals have properties tht make them useful for building and making things
      1. Copper is used for wiring
    3. Copper, Gold and aluminium are all alloyed with other metals to make them harder
  7. C1 3.6
    1. There are social, economic and environmental issues associated with exploiting metal ores
    2. Plants can remove metals from low-grade ores.
      1. The metals can be recovered by processing the ash from burning the plants
    3. Recycling metals saves energy and our limited metal ores (and fossil fuels)
      1. The pollution from extracting metals is also reduced
    4. There are drawbacks as well as benefits from the use of metals in structures

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AQA Science Chemistry key points

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