Inorganic chemistry

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  • Created by: Kayliss71
  • Created on: 21-05-18 10:04
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  • Inorganic chemistry
    • Periodicity
      • The periodic table arranges elements by proton number
      • Melting point is linked to bond strength and structure
      • Ionisation energy generally increases across a period
        • This is because of the increasing attraction between the outer shell electrons and the nucleus
      • Atomic radius decreases across a period
        • This is due to extra protons increasing the positive charge of the nucleus so electrons are pulled closer to the nucleus making the atomic radius smaller
    • Group 2
      • Atomic radius increases down the group
        • Due to the extra electron shells that are added
      • First ionisation energy decreases down the group
        • Each element down group 2 has an extra electron shell
        • Due to the extra shells shielding occurs and shells are further away from positive nucleus so attraction is weaker
      • Melting point generally decrease down the group
        • Have typical metallic structures, going down the group metal ions get bigger but number of delocalised electrons stay the same
        • Larger the ionic radius = further away delocalised electrons are from positive nuclei so less attraction so less energy needed to break bonds
      • Reactions with water
        • Be doesn't react
        • Mg reacts very slowly
        • Ca reacts steadily
        • Sr reacts fairly quickly
        • Ba reacts rapidly
      • Reactivity  increases down the group, weaker the ionisation energy = more reactive
      • Uses of group 2 metals
        • Calcium hydroxide is used in agriculture to neutralise soils
        • Magnesium hydroxide is used in some indigestion tablets to neutralise excess stomach acid
        • Barium sulfate is used in barium meals which help soft tissue to show up on x-rays
        • Magnesium is used in the extraction of titanium
        • Calcium oxide and calcium carbonate is used to remove sulfur dioxide
      • Use flame tests to identify Group 2 ions
        • Calcium- brick red
        • Strontium - red
        • Barium- pale green
    • Group 7
      • Boiling points increase down the group  due to increasing van der waals as size and relative  mass increases
      • Electronegativity decreases down the group due to electron shielding
      • Halogens displace less reactive halide ions from solution
        • Halogens become less oxidising down the group
      • Uses of group 7
        • Chlorine and sodium hydroxide make bleach
          • 2NaOH + Cl2 --> NaClO + NaCl + H2O
        • Chlorine is used to kill bacteria in water
      • Halides
        • Their reducing powers decrease down the group
        • Reactions with sulfuric acid
          • NaF + H2SO4 -> NaHSO4 + HF                  *same for NaCl
          • 1)            NaBr + H2SO4 --> NaHSO4 + HBr
            • 2)                   2HBr + H2SO4 --> Br2 + SO2 + 2H2O
          • 1)        NaI + H2SO4 -->  NaHSO4 + HI
            • 2)          2HI + H2SO4 --> I2 + SO2 +2H20
              • 3)             6HI + SO2 --> H2S + 3I2 + 2H2O
        • Silver nitrate is used to test for halides
          • Fluoride - no precipitate
          • Chloride - white precipitate
          • Bromide - cream precipitate
          • Iodide - yellow precipitate
          • You can test your results by adding ammonia solution
            • Chloride - white precipitate, dissolves in dilute ammonia solution
            • Bromide- cream precipitate, dissolves in conc ammonia solution
            • Iodide- yellow precipitate, insoluble in conc ammonia solution
    • Period 3 elements and metal oxides
      • Reactions with water
        • Sodium  reacts vigorously with cold water ( pH 12-14)
          • 2Na + 2H2O  --> 2NaOH + H2
        • Magnesium reacts very slowly with cold water and forms a weakly alkaline solution (pH 9-10)
          • Magnesium is sparingly soluble, so reacts faster with steam
      • Reactions with oxygen
        • Sodium oxide:   2Na + 1/2O2 --> Na2O
          • Reacts vigorously
        • Aluminium oxide;  2Al + 1 1/2O2 --> Al2O3
          • Slow (reacts faster if powdered)
        • Phosphorus (v) oxide; P4 + 5O2 --> P4O10
          • Spontaneous combustion
        • Magnesium oxide; Mg + 1/2O2 --> MgO
          • reacts vigorously
        • Silicon dioxide: Si + O2 --> SiO2
          • Slow
        • Sulfur dioxide; S + O2 --> SO2
          • Burns steadily
      • Simple non metal covalent oxides
        • Form strong acids
        • Phosphoric (V) acid : 1)  P4O10 + 6H2O --> 4H3PO4
          • 2) H3PO4 --> 3H(+) + PO4(3-)
        • Sulfurous acid: 1)   SO2 + H2O --> H2SO3
          • 2) H2SO3 --> 2H(+) + SO3(2-)
        • Sulfuric (VI) acid : 1)  SO3 + H2O --> H2SO4
          • 2) H2SO4 --> 2H(+) + SO4(2-)
      • Neutralising Equations
        • Basic oxides neutralise acids
          • Na2O + 2HCL --> 2NaCl + H2O
          • MgO + H2SO4 --> MgSO4 + H2O
        • Acidic oxides neutralise bases
          • SiO2 + 2NaOH --> Na2SiO3 + H2O
          • P4O10 + 12NaOH --> 4Na3PO4 + 6H2O
          • SO2 + 2NaOH --> Na2SO3 + H2O
          • SO3 + 2NaOH --> Na2SO4 + H2O
        • Amphoteric oxides neutralise acids and bases
          • Acid: Al2O3 + 3H2SO4 --> Al2(SO4)3 + 3H2O
          • Base: Al2O3 + 2NaOH + 3H2O --> 2NaAl(OH)4
    • Tests for Ions
      • Use red litmus paper to test for ammonium ions - paper will turn from red to blue
        • Red litmus paper will also turn blue if hydroxides are present
      • Use HCL and barium chloride to test for sulfates - a white precipitate will form
      • Red litmus paper will also turn blue if hydroxides are present
      • Use HCL to test for carbonates, will fizz if present and gas given off will turn lime water cloudy when bubbled through (if gas is CO2)

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