Question

Al and Ga have the same covalent radius because of

• A. Greater shielding of $s$ - electrons of $Ga$ atoms
• B. Poor shielding of $s$- electrons of $Ga$ atoms
• C. Poor shielding of $d$ - electrons of $Ga$ atoms
• D. Greater shielding of $d$ - electrons of $Ga$ atoms

Answer 1

Answer: (C)

Poor shielding of $d$ - electrons of $Ga$ atoms

Poor shielding increases the effective nuclear charge, thereby decreasing atomic radius. This effect counterbalances the effect of increase in atomic radius due to addition of another shell.