4: Inorganic chemistry

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Trend in gp2 ionisation energy
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Decreases down group as electrons increases, shells increases and shielding increases so there is a weaker attraction between electrons and nucleus so outer electrons can be removed more readily
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Trend in gp2 reactivity
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Increases down group as more shells and shielding means electrons are less strongly attracted to nucleus so are more readily removed
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O2 + Mg reaction
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Bright white flame forming a white solid MgO
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O2 + Ca
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Red flame forming white solid CaO
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O2 + Ba
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Pale green flame forming BaO
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H2O + Mg
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Slow reaction, faster on heating
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H2O + Ca
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White ppt
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H2O + Ba
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Very fast reaction
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Gp2 + Cl
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White chlorides
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Gp2 + dilute acid
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Form salts
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Gp2 hydroxides + dilute acid reactivity
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Decreases down group, forms white precipitate
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Trend in solubility of the hydroxides
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Increases down
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Trend in solubility of the sulphates
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Decreases down group forming colourless solids
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Trend in gp 1+2 carbonates and nitrates thermal stabilities
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Decreases solubility up groups as the larger the charge on the ion and the smaller the radius, the greater it’s charge density and so the greater polarising power which attracts the bonding electrons in neighbouring ions more strongly. The pull distorts the bonding and makes it easier to break up the negative ion into an oxide ion
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How to carry out a flame test
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Place nichrome wire in HCl, then into the substance and then into a blue flame and record results
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How a flame test works
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When the substance is heated, the electrons move to a higher energy level. When they fall back down the energy is released in the form of light
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Flame test: lithium
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Brick red
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Flame test: sodium
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Yellow
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Flame test: potassium
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Lilac
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Flame test: calcium
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Brick red
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Flame test: strontium
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Crimson
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Flame test: barium
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Pale green
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Test the thermal decomposition of nitrates
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Time it takes for a certain amount of oxygen to be produced
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Test the thermal decomposition of carbonates
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Time it takes for a certain amount of carbon dioxide to be produced
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Trend in Mp+Bp in gp7
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Increases down the group as there are more electrons, and so the molecules are more polarisable leading to larger induced dipoles and so stronger London forces
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Trend in physical state in gp7
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More solid as you go down group due to Bp
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Trend in electronegativity in gp7
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Decreases down the group as the atomic radius increases due to more shells and shielding and so the outer electrons are less strongly attracted to the nucleus so less energy is needed to ionise them
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Trend in reactivity down gp7
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Reactivity decreases down group as the electrons are less strongly attracted to outer electrons and so electrons are less readily gained as there is a weaker force of attraction
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Oxidation strength of halogens
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Decreases due to decrease in reactivity
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Halogens + cold alkali equation
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Cl2 + OH- –> ClO- + Cl- + H2O
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Halogens + hot alkali equation
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3Cl2 + 6OH- –> ClO3- + 5Cl- + 3H2O
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Halogens + water equation
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Cl2 + H2O –> HCl + HClO
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Cl test and results
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Silver nitrate + dilute nitric acid forming a white ppt
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Br test and result
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Silver nitrate + dilute nitric acid forming a cream ppt
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I test and reault
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Silver nitrate + dilute nitric acid forming a yellow ppt
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Test to tell Cl and Br apart
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Add ammonia and Cl dissolves forming a colourless solution by Br stays unchanged
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Hydrogen halides + water
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Misty fumes of acidic gas, turns damp blue litmus paper red
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Hydrogen halides + ammonia gas
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White fumes
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Test for carbonates
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Add HCl, test CO2 produced
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Test for SO4-
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Add BaCl, white ppt
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Test ammonia
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Test gas by turning damp red litmus paper blue

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