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12 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Group 2 reactivity |
Going down the group, ionization energy decreases, so the outer electrons are lost more easily and reactivity increases |
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Reactions of group 2 elements |
Group 2 metals react with water to produce metal hydroxides and hydrogen. Group 2 metals burn in oxygen to produce solid white oxides. Group 2 metals react with chlorine to produce solid white chlorides. |
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Reactions of group 2 metal oxides |
Group 2 metal oxides react readily with water to produce metal hydroxides which dissolve, giving strongly alkaline solutions. ● Beryllium oxide doesn't react with water and beryllium hydroxide is insoluble. ● Magnesium oxide reacts slowly and magnesium hydroxide is very insoluble. Group 2 metal hydroxides become more soluble going down the group. Both metal oxides and hydroxides are bases so neutralise dilute acids, producing solutions of the corresponding salts. |
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Solubility of group 2 metal hydroxides and sulphates |
Solubility of group 2 metal hydroxides (and other singly charged anions) increases down the group ● beryllium hydroxide is insoluble Solubility of group 2 metal sulphates (and other doubly charged anions) decreases down the group ● barium sulphate is insoluble |
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Thermal stability of group 1 and 2 nitrates and carbonates |
Going down the group, the cations become larger and charge density decreases as the charge of the ion is spread over a larger area, so the cation polarises the anion less, causing less distortion and making the compound more stable. Group 2 cations have a greater charge density than group 1 cations, as the greater charge of the ion is spread over a smaller area, so the cation polarises the anion more, causing more distortion and making the compound less stable. |
Group 1 carbonates are thermally stable and decompose at high temperatures, except lithium which decomposes like group 2 carbonates. Group 2 carbonates decompose to form the solid oxide and CO2. Group 1 nitrates decompose to form the solid nitrite and O2, except lithium which decomposes like group 2 nitrates. Group 2 nitrates decompose to form the oxide, NO2 and O2. |
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Group 1 and 2 flames |
The energy absorbed from the flame causes electrons to move to higher energy levels. The colours are seen as the electrons fall back down to lower energy levels, releasing energy in the form of light. The difference in energy between the higher and lower levels determines the wavelength of the light released - which determines the colour of the light. |
Lithium - red Sodium - yellow Potassium - lilac Rubidium - red Caesium - blue Calcium - brick red Strontium - crimson Barium - green |
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Reactivity and electronegativity of halogens |
Going down the group, atomic radius increases and number of shielding electrons increases, reducing the attraction of the outer electrons with the nucleus so an extra electron is harder to gain, so reactivity decreases. Electronegativity also decreases down the group as the attraction of the bonding electrons with the nucleus weakens. |
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Melting and boiling point of halogens |
Going down the group, number of electrons increases, so the London forces between the molecules get stronger. More energy is needed to overcome the intermolecular forces, so melting and boiling point increase |
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Displacement reaction |
One element replaces another element in a compound. A more reactive halogen displaces a less reactive halide ion in aqueous solution, and a colour change will occur. The addition of an organic solvent, like hexane, makes the colour change easier to see. The halogen dissolves in the organic solvent, which forms a layer above the aqueous solution. |
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Properties of halogens |
They exist as covalent, diatomic molecules. They're non polar so have low solubility in water but dissolve easily in organic solvents. Halide ions dissolve. They're oxidizing agents. |
● Flourine is a pale yellow gas. ● Chlorine is a green gas. ● Bromine is a red/ brown liquid. ● Iodine is a grey solid. ■ Chlorine is virtually colourless in water and hexane. ■ Bromine is yellow/ orange in water and orange/red in hexane. ■ Iodine is brown in water and pink/ violet in hexane. |
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Halogens and group 1 and 2 metals |
When halogens react with group 1 and 2 metals, they're reduced while the metal is oxidized, producing halide salts. |
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Disproportionation reactions of halogens |
Halogens react with cold dilute aqueous alkali solutions in disproportionation reactions to form halide salts with +1 and -1 oxidation numbers. Halogens react with hot alkali solutions in disproportionation reactions to form halide salts with +5 and -1 oxidation numbers. Halogens react with water in disproportionation reactions to form halide acids with +1 and -1 oxidation numbers. |
Chlorine gas undergoes disproportionation with cold dilute aqueous NaOH to produce NaClO (bleach), NaCl and H20. Chlorine gas undergoes disproportionation with hot NaOH to produce NaClO3, NaCl and H2O. Chlorine gas undergoes disproportionation with water to produce HCl and HClO. The hypochlorous acid ionises to form hypochlorite ions, ClO-, which kills bacteria so can be used for water treatment. |
