3.31 The first and the second ionization enthalpies (in ) electron gain enthalpy (in ) of a few elements are given below:
Elements
I 520 7300 –60
II 419 3051 –48
III 1681 3374 –328
IV 1008 1846 –295
V 2372 5251 +48
VI 738 1451 –40
(e) the metal which can form a stable binary halide of the formula (X=halogen).
The metal that can form a stable binary halide of the formula: (X=halogen) is the element VI, which has a low first ionisation enthalpy but higher than that of alkali metals. Hence, it is an alkaline earth metal and forms a binary halide.