C2 GCSE

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  • C2-Periodic Table
    • Development of periodic table
      • John Dalton first put elements in order of atomic weights
      • In 1864 John Newlands ordered them by mass but realised every 8th element had different properties
        • He made a 'law of octaves' but didn't make space for new elements and his theory proved to be wrong
      • Mendeleev
        • In 1869, arranged 50 elements according to atomic weights and arranged them in periods according to their properties
        • He left gaps for undiscovered elements
    • Group 1- The alkali metals
      • All alkali metals are very reactive and they have to be stored in oil to stop reacting with oxygen
        • They have a silvery shiny surface when you first cut the. However, they quickly go dull when they react with oxygen in the air. It forms a layer of oxide on the shiny surface.
          • In a jar of oxygen, hot alkali metals burn vigorously, forming white smoke of their oxide
          • They are also very soft
      • They all have 1 electron on their valence shell
      • They are more reactive as you go down the group
        • This is because as you go down the group, it is easier to lose an electron because there is less attraction between the valence shell an nucleus, making it more reactive as you go down
      • Reactions
        • Reaction with water
          • All alkali metals have a low density so they float on water: 1g/cm3
          • When they react with water, they float and fizz because they form hydrogen gas
          • They also produce metal hydroxide; why it's called alkali metals
          • Potassium reacts so vigorously with water that the hydrogen produced ignites. It burns with a lilac flame, coloured by the potassium ions formed in the reaction
        • Reaction with non-metals like chlorine
          • They also react vigorously with non-metals like chlorine and produce metal chlorides which are white solids
            • These metal chlorides all dissolve readily in water to form colourless solutions
    • Group 7-Halogens
      • These are a group of toxic non-metals that have coloured vapours
        • They get less reactive as you go down the group
          • They are poor conductors of heat and electricity
          • Melting and boiling points increase as you go down the group
          • Fluorine is a very reactive poisonous yellow gas
          • Chlorine is a fairly reactive poisonous dense green gas
          • Bromine is a dense poisonous red brown volatile liquid
          • Iodine is a dark grey crystalline solid
            • Or purple vapour
      • They exist as pairs of atoms; called diatomic molecules
        • They can displace less reactive halogens
          • A more reactive halogen will displace a less reactive halogen from solutions of its salts
    • Transition elements
      • Physical properties
        • They are good conductors of electricity and thermal energy
          • Hard and strong
          • Have high densities
        • High melting points except Mecury
      • Chemical properties
        • Less reactive that Alkali metals
          • Metals can have(II) or (III), meaning they can form different ions
    • Noble gases
      • Group 0 are all inert colourless gases
        • This is because they all have full valence shells so they do not need to react
          • They are non-flammable and colourless at room temperature
            • They exist as monatomic gases; single atoms not bonded to each other
              • As you go down the group the boiling and melting points increase because there is a higher number of electrons which means greater inter-molecular forces

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