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The first (ΔiH1) and the second (ΔiH2) ionization enthalpies (in kJ mol-1) and the (ΔegH) electron gain enthalpy (in kJ mol-1) of a few elements are given belowElements ΔH1 ΔH2 ΔegHI 520 7300 -60II 419 3051 -48III 1681 3374 -328IV 1008 1846 -295V 2372 5251 +98VI 738 1451 -40Which of the above elements is likely to be:(a) The least reactive element(b) The most reactive metal(c) The most reactive non-metal(d) The least reactive non-metal(e) The metal which can form a stable binary halide of the formula MX2 (X = halogen).(f) The metal which can form a predominantly stable covalent halide of the formula MX (X = halogen)? |
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Answer» (a) Element V has highest ionization enthalpy. Hence it is the least reactive element. (b) The element having the lowest first ionization enthalpy will tend to lose electron easily and hence would be a reactive metal. Thus, II in the most reactive metal. (c) The non-metals have high ionization enthalpies (but less than that of noble gases). The element III is thus most reactive non-metal. (d) The element IV is least reactive non-metal. (e) Metals have relatively lower volumes of ionization enthalpies. The first ionization enthalpy of elements in group II is higher than that of element in group I. Since the element M forms a stable binary halide of the formula MX2, M should belong to the group II of the periodic table. The sum of IE1 and IE2 for a group 2 element is less than that of its neighbours. Keeping this in mind, VI appears to be metal capable of forming a stable halide of the formula MX2. (f) I element can form a predominantly stable covalent halide of the formula MX (X = halogen). |
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