The reason for the small radius of Ga compared to Al is-.
a. Poor screening effect of d and f orbitals
b. Increase in nuclear charge
c. Presence of higher orbitals
d. Higher atomic number
Choose the correct option
1. (a, b)
2. (b, c)
3. (c, d)
4. (a, d)
Hint: The 3d10 electrons do not screen the nuclear charge in an effective manner in Ga.
The smaller value of gallium in comparison to aluminium is due to the fact that in going from Al to Ga the penultimate d-orbitals are filled in the first
d-block series from Sc(2l) to Zn (30). The d-electrons do not screen the nuclear charge in an effective manner and therefore, the electrons in the
outermost shell of gallium (135 pm) experience more force of attraction towards nucleus than aluminium (143 pm), causing thereby decrease in atomic radius.