Given below are two statements:

Statement I: The decrease in first ionization enthalpy from B to Al is much larger than that from Al to Ga.

Statement II: The d orbitals in Ga are completely filled.

Question

Given below are two statements:

Statement I: The decrease in first ionization enthalpy from B to Al is much larger than that from Al to Ga.

Statement II: The d orbitals in Ga are completely filled.

Canvas Classes · Accepted Answer

🧠 Ga has a fully filled  in its core — those 3d electrons shield poorly, so Ga's  barely drops below Al's
This is the classic d-block contraction story. Boron to Aluminium: simple shell increase, IE drops sharply. Aluminium to Gallium: a whole d-subshell of 10 poorly-shielding electrons gets in between, raising  on Ga's outer 4p electron and keeping  nearly flat.

🗺️ Statement I check
, , . Drop B→Al is 224. Drop Al→Ga is barely 0 (actually slightly increases). So the drop B→Al is much larger

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