Give reason:

Iron has a higher enthalpy of atomization than that of copper.

Transition metal has the high heat of atomisation due to the presence of strong metallic bond which arises due to the presence of an unpaired electron in the (n - 1) d subshell. This is because the atoms in these elements are closely packed and held together by strong metallic bonds. The metallic bond is formed as a result of the interaction of electrons in the outermost shell. Greater the number of valence electrons, stronger is the metallic bond.