JEE MainChemistryd and f Block Elements
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Metals like Zinc, Cadmium, and Mercury are soft and have very low enthalpies of atomization compared to typical transition metals. Reason (R): The completely filled (n-1)d¹⁰ subshell in these elements prevents the involvement of d-electrons in metallic bonding. In the light of the above statements,
Options
- ABoth (A) and (R) are correct and (R) is the correct explanation of (A).
- BBoth (A) and (R) are correct but (R) is NOT the correct explanation of (A).
- C(A) is correct but (R) is not correct.
- D(A) is not correct but (R) is correct.
Correct answer
A. Both (A) and (R) are correct and (R) is the correct explanation of (A).
Step-by-step solution
In typical transition metals, unpaired d-electrons participate in delocalized metallic bonding, leading to strong metallic bonds and high enthalpies of atomization. However, Zinc, Cadmium, and Mercury have a general electronic configuration of (n-1)d¹⁰ns² . Because their d-subshells are completely filled, these d-electrons do not participate in metallic bonding. This results in weak metallic bonds, making these metals soft and giving them exceptionally low enthalpies of atomization. Thus, both Assertion (A) and Rea