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Classification of Elements and Periodicity in Properties

Long Answer Type

181.

What is the basic difference between the terms electron gain enthalpy and electronegativity?

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182.
The first $left parenthesis increment subscript straight i straight H subscript 1 right parenthesis$ and the second $left parenthesis increment subscript straight i straight H subscript 2 right parenthesis$ ionization enthalpies (in kJ mol^-1) and the $left parenthesis increment subscript eg straight H right parenthesis$ electron gain enthalpy (in kJ mol^-1) of a few elements are given below:
Elements $increment straight H subscript 1$ $increment straight H subscript 2$ $increment subscript eg straight H$
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 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)?

Element V is likely to be the least reactive element. This is because it has the highest first ionisation enthalpy (Δ_iH1) and a positive electron gain enthalpy (Δ_egH).It is a noble gas

(b) Element II is likely to be the most reactive metal as it has the lowest first ionisation enthalpy (ΔiH1) and a low negative electron gain enthalpy (ΔegH).The with lowest first ionisation enthalpy is likely to be a reactive metal

(c) Element III is likely to be the most reactive non–metal as it has a high first ionisation enthalpy (Δ_iH1) but less than the noble gas elements and the highest negative electron gain enthalpy (ΔegH).

(d) Element V is likely to be the least reactive non–metal since it has a very high first ionisation enthalpy (Δ_iH2) and a positive electron gain enthalpy (Δ_egH).

(e) Element VI has a low negative electron gain enthalpy (ΔegH). Thus, it is a metal. Further, it has the lowest second ionisation enthalpy (Δ_iH2). Hence, it can form a stable binary halide of the formula MX₂ (X=halogen).

(f) The element I have low first ionisation energy and high second ionisation energy. Therefore, it can form a predominantly stable covalent halide of the formula MX (X=halogen).

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