Chemistry - PERIODIC TABLE Question with Solution | TestHub
Statement-1: The first ionization enthalpy of Gallium (Ga) is higher than that of Aluminum (Al).
Statement-2: The poor shielding effect of the 3p electrons in Gallium leads to an increase in the effective nuclear charge experienced by its outermost 4p electron, resulting in a smaller atomic radius and greater attraction towards the nucleus.
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Solution:
Gallium (Ga) follows Aluminum (Al) in the periodic table. Despite the expected decrease in ionization enthalpy down a group, Ga has a slightly higher first ionization enthalpy than Al (Al: 577.5 kJ/mol, Ga: 578.8 kJ/mol).
This is due to the poor shielding effect of the 3d electrons in Ga. The 3d electrons are relatively diffuse and do not effectively shield the outermost 4p electron from the nuclear charge, leading to a higher effective nuclear charge () experienced by the 4p electron. This results in a smaller atomic radius for Ga than expected and a stronger attraction of the nucleus for the valence electron, making it harder to remove.
