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AlkalineEarth Metals
Unit 2 AQA A Level Chemistry
Question | Answer |
---|---|
Size of atoms going down the group? | Atoms get bigger going down the group as no. of main energy levels increases |
Melting points down the group? | Melting points decrease down the group as the extra main energy levels increase shielding and mean the +ve nucleus is further from the sea of delocalised e- |
Reactivity/ionisation energies down the group? | Ionisation energies decrease going down the group as the extra main energy levels increase shielding. Therefore the metals get more reactive going down the group. |
Reaction equation for the metals with water | x + 2H2O --> x(OH)2 + H2 (x=metal. Reactions get faster/more vigorous going down the group. |
Reaction equation for magnesium with steam | Mg + H2O --> MgO + H2 |
Solubilities of hydroxides going down the group? | Increase in solubility going down the group. Magnesium hydroxide is virtually insoluble. |
Medicinal use of 'Milk of Magnesia' (Magnesium Hydroxide)? | Used in indigestion remedies to neutralise stomach acid |
Solubilities of sulphates going down the group? | Decrease in solubility going down the group. Barium sulphate is virtually insoluble. |
Medicinal use of barium sulphate? Why is this safe? | 'Barium meal' to outline the gut in x-rays. Safe because barium sulphate is so insoluble. |
What group 2 ion is used to test for sulphate ions? Why? | Barium ions, because an insoluble white ppt. of barium sulphate will form. |
Reaction equation for barium ions identifying sulphate ions | Ba2+ + SO42- ---> BaSO4 |
Method for identifying sulphate ions | Solution acidified with nitric or hydrochloric acid to remove impurities such as carbonate ions. Barium ions then added in the form of barium chloride. |