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The increasing order of reactivity among group-1 elements is Li lt Na lt K lt Rb lt Cs whereas that among group 17 elements is F gt CI gt Br gt I. |
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Answer» SOLUTION :The elements of GROUP-1 have only one electron in their outermost shells and therefore, have strong tendency to lose this electron. The tendency of these elements to lose the valence electron depends upon the ionization enthalpy. Since ionization enthalpy decreases down the group, therefore the reactivity of group-1 elements increases in the same order `Li lt Na lt K lt KB lt Cs`. On the other hand, the elements of group-17 have seven ELECTRONS in their respective valence shells and therefore, they, have strong tendency to accept one more electron . The tendency to accept ADDITIONAL electrons depends upon the electrode potentials of group17 elements. The electrode potential of group 17 elements decreases fromF to I `[F = +2.86V, Cl = + 1.36V, " Br " = + 1.08 V " and " I = +0.53V]` and therefore , their reactivities also decrease in the same order as `F gt Cl gt Br gt I`. |
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