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Chemical Periodicity (Group 0: The Noble Gases (Uses (Argon (To provide an…

- - - - To provide an inert atmosphere, e.g lightbulb filament, food packaging
    - - Lasers
    - - Gas discharge tubes, to make neon advertising signs
    - - Flash lamps for cameras
    - - Party balloons and airships, as it is less dense than air
- - - - Caesium melts in the hand
    - - Except Caesium, which is a pale gold colour
    - - Lustrous when freshly cut, however they tarnish rapidly
    - - They are the most reactive metal group, and are stored under oil, or in an argon atmosphere
    - - Lithium, Sodium and Potassium float on water
    - - They can easily be cut by a sharp knife
  - - - They become softer
      - They increase in reactivity
      - They become more reactive
      - They increase in density
  - - - 4Na(s) + O2(g) --> 2Na2O(s)
    - - 2K(s) + 2H2O(l) --> 2KOH(aq) + H2(g)
      - Lithium reacts vigorously, moving around on the surface of the water, effervescing, and appearing to disappear, as it forms soluble lithium hydroxide
      - Sodium reacts more vigorously, moving around on the surface of the water as a molten ball, effervescing, and appearing to disappear, as it forms soluble sodium hydroxide. With more heat produced, and sodium's lower melting point, the solid becomes molten, and forms a ball of liquid metal
      - Potassium reacts violently, moving around on the surface of the water as a molten ball, effervescing, and appearing to disappear, as it forms soluble potassium hydroxide. Enough heat is produced to ignite the hydrogen gas, and thus a flame is seen, coloured lilac due to the presence of potassium
- - - - Pale green gas, dense and toxic. Forms a colourless solution in water
    - - Dense, dark red liquid, gives off brown vapour. Toxic and corrosive. Forms an orange solution in water and organic solvents
    - - Pale yellow gas, very toxic and extremely reactive
    - - Dark grey solid, sublimes to give purple vapour. Forms a brown solution in water, and a purple solution in organic solvents
  - - - They become darker in colour
      - They increase in melting/boiling point
      - They become less reactive (opposite of the alkali metals, as the larger numbers of outer shells mean it is more difficult to attract an electron
  - - - 2Na(s) + Cl2(g) --> 2NaCl(s)
    - - Bromine + Sodium Iodide
        
        The orange bromine water reacts with the colourless sodium iodide solution, producing a brown solution due to the formation of aqueous iodine. To confirm that the colour is due to iodine, add hexane and shake, forming a layer above the aqueous solution, into which the iodine is absorbed, forming purple solution
        
        Br2(aq) + 2I-(aq) 2Br-(aq) + I2(aq) (ionic)
        
        Br2(aq) + 2NaI(aq) --> 2NaBr(aq) + I2(aq) (formula)
      - Chlorine + Sodium Iodide
        
        Cl2(aq) + 2I-(aq) --> 2Cl-(aq) + I2(aq) (ionic)
        
        The colourless chlorine water reacts with the colourless sodium bromide solution, producing a brown solution due to the formation of aqueous iodine. To confirm that the colour is due to iodine, add hexane and shake, forming layer above the aqueous solution, into which the iodine is absorbed, forming a purple solution
        
        Cl2(aq) + 2NaI(aq) --> 2NaCl(aq) + I2(aq) (formula)
      - Chlorine + Sodium Bromide
        
        Cl2(aq) + 2Br-(aq) --> 2Cl-(aq) + Br2(aq) (ionic)
        
        The colourless chlorine water reacts with the colourless sodium bromide solution, producing an orange solution due to the formation of aqueous bromine. To confirm that the colour is due to bromine, add hexane and shake, forming a layer above the aqueous solution, into which the bromine is absorbed, forming an orange solution
        
        Cl2(aq) + 2NaBr(aq) --> 2NaCl(aq) + Br2(aq) (formula)
    - - Sodium chloride, sodium bromide and sodium iodide are all white, crystalline salts and dissolve readily in water to form colourless solutions. The halide ions can be tested for b y adding some nitric acid to remove carbonate ions, which would give a false positive for chlorine, and then adding silver nitrate solution
      - Silver Chloride
        
        White precipitate
      - Silver Bromide
        
        Cream precipitate
      - Silver Iodide
        
        Yellow precipitate
    - - Colourless gases, formed from covalently bonded molecules. When dissolved in wate, these solutions give off H+ ions, therefore acidic solution. However, if dissolved in other solvents, such as methylbenzene, the molecules do not split up, and no H+ ions are released, meaning the solution is not acidic