Question

The transition element that has lowest enthalpy of atomization is:
(A) $Zn$
(B) $Cu$
(C) $V$
(D) $Fe$

Answer 1

Hint : Enthalpy of atomization is linked with the strength of the metallic bonds present in different metals. Transition elements are the elements belonging to the d-block of the periodic table and usually consist of strong metallic bonds.

Complete Step By Step Answer:
Transition elements are characterized by their ability to show variable oxidation states and form strong metallic bonds due to which they are called hard metals and have extremely high melting and boiling points.
The ability to form strong metallic bonds originates from the presence of unpaired electrons in the valence shell. As the number of unpaired electrons increases on going left to right in the transition metal series, the tendency to form metal-metal bonds also enhances. Therefore the strength of metallic bonds increases from scandium to manganese and then goes on decreasing as the electrons again start to form pairs.
The enthalpy of atomization is directly proportional to the strength of metallic bonds i.e. stronger bonds require higher energies to break apart and give individual atoms. Therefore the enthalpy of atomization also depends on the number of unpaired electrons.
Though zinc has the least number of unpaired electrons yet it is not the transition metal with lowest atomization enthalpy. The transition metal with lowest enthalpy of atomization is copper (with only one unpaired electron).
Hence, the correct option is (B) $Cu$ .

Note :
Zinc has the lowest enthalpy of atomization but it is not considered a transition metal as it is the last member of the transition metal series and has a completely filled d-orbital. Due to the lack of unpaired electrons, zinc does not show any characteristic property of transition metals and therefore does not fall under the category of transition metal.