Question -
| Elements | ΔiH | ΔiH | ΔegH |
| I | 520 | 7300 | –60 |
| II | 419 | 3051 | –48 |
| III | 1681 | 3374 | –328 |
| IV | 1008 | 1846 | –295 |
| V | 2372 | 5251 | +48 |
| VI | 738 | 1451 | –40 |
Which of the aboveelements is likely to be :
(a) the least reactiveelement.
(b) the most reactivemetal.
(c) the most reactivenon-metal.
(d) the least reactivenon-metal.
(e) the metal which can form a stable binaryhalide of the formula MX2, (X=halogen).
(f)the metal which can form a predominantly stable covalent halide of the formulaMX (X=halogen)?
Answer -
(a) ElementV is likely to be the least reactive element. This is because it has thehighest first ionization enthalpy (ΔiH1) and a positive electron gain enthalpy (ΔegH).
(b) Element II islikely to be the most reactive metal as it has the lowest first ionizationenthalpy (ΔiH1) and a low negative electron gain enthalpy (ΔegH).
(c) Element III islikely to be the most reactive non–metal as it has a high first ionizationenthalpy (ΔiH1) and the highest negative electron gain e(a) ElementV is likely to be the least reactive element. This is because it has thehighest first ionization enthalpy (ΔiH1) and a positive electron gain enthalpy (ΔegH).
(b) Element II islikely to be the most reactive metal as it has the lowest first ionizationenthalpy (ΔiH1) and a low negative electron gain enthalpy (ΔegH).
(c) Element III islikely to be the most reactive non–metal as it has a high first ionizationenthalpy (ΔiH1) and the highest negative electron gain enthalpy (ΔegH).
(d) Element V islikely to be the least reactive non–metal since it has a very high firstionization enthalpy (ΔiH2) and a positive electron gain enthalpy (ΔegH).
(e) Element VI has alow negative electron gain enthalpy (ΔegH). Thus, it is ametal. Further, it has the lowest second ionization enthalpy (ΔiH2). Hence, it can form a stable binary halide of theformula MX2 (X=halogen).
(f) Element V has the highest first ionization energyand high second ionization energy. Therefore, it can form a predominantlystable covalent halide of the formula MX (X=halogen).
nthalpy (ΔegH).
(d) Element V islikely to be the least reactive non–metal since it has a very high firstionization enthalpy (ΔiH2) and a positive electron gain enthalpy (ΔegH).
(e) Element VI has alow negative electron gain enthalpy (ΔegH). Thus, it is ametal. Further, it has the lowest second ionization enthalpy (ΔiH2). Hence, it can form a stable binary halide of theformula MX2 (X=halogen).
(f) Element V has the highest first ionization energyand high second ionization energy. Therefore, it can form a predominantlystable covalent halide of the formula MX (X=halogen).