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| Electrochemical Series of Metals |
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| Different metals get ionised at different rates. For e.g., metals like sodium when exposed to air combine almost instantly with the oxygen present therein (sodium atom gives up an electron almost as soon as it is in contact with oxygen). On the other hand, metals like gold if exposed to air even for a very long period, do not react with air. Even if gold is dropped into an acid, it remains unaffected. |
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| Based on the ease with which metals lose their electrons and form their ions, the metals are also arranged in a series called Metal Activity Series. Metals that ionise most easily are placed at the top of the Metal Activity Series, and those that ionise least easily are placed at the lower most end. |
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| Most of the elements of the periodic table can be arranged in such a fashion, which reflects their order of activity. This arrangement of elements in order of their increasing rates of ionisation i.e. oxidising and reducing strength, is also called the activity series or the electrochemical series. |
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| Electrochemical Series |
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| (Ease of discharge increases downwards) |
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| Features of the electrochemical series (Activity series) |
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 In the electrochemical series the elements that are lower in the series get discharged (lose their charge to become neutral) more easily than the ones above them. |
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Hydrogen is also included as a reference point in the series. |
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The electropositive power and the reducing power of the elements regularly decrease downwards while the electronegative power and the oxidizing power of the elements regularly increase upwards. |
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| Significance of the electrochemical series (Activity series) |
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| This series is an important tool that helps in predicting many electrochemical reactions. |
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All metals placed above hydrogen will displace hydrogen from acids while those below it do not displace hydrogen from acids. |
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Elements with high electropositive or electronegative power are highly reactive elements. |
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Each element in the series will displace any other element below it from a solution of its salt. For e.g., when we add zinc turnings in copper sulphate solution, copper is replaced by zinc because zinc is in higher position as compared to copper. |
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In the replacement of one metal ion from its solution by another metal, the element that gives up electrons most easily to become an ion will be in the solution. This is because it will accept the electrons back with greatest difficulty. |
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