NEETChemistryd and f Block Elements
Among the elements of the first transition series, zinc exhibits the lowest enthalpy of atomisation ( 126 kJ mol ⁻¹ ). What is the primary fundamental reason for this observation?
Options
- AThe high effective nuclear charge of zinc tightly binds its valence electrons.
- BThe exceptional stability of its completely filled 4s orbital prevents metallic bonding.
- CThe absence of unpaired electrons in its 3d subshell leads to weak interatomic metallic bonding.
- DThe relatively larger atomic radius of zinc decreases the electrostatic attraction between atoms.
Correct answer
C. The absence of unpaired electrons in its 3d subshell leads to weak interatomic metallic bonding.
Step-by-step solution
The enthalpy of atomisation is a direct measure of the strength of interatomic metallic bonds in a solid lattice. In transition metals, the strength of metallic bonding depends largely on the number of unpaired electrons available in the (n-1)d subshell, which participate in bonding along with the ns electrons. Zinc has a ground state electronic configuration of [ Ar ] 3d¹⁰ 4s² . Because its 3d subshell is completely filled, it possesses no unpaired d -electrons to contribute to the metallic bond. This lack of unpa