Question

The enthalpies of atomization of transition metal is high. Give reason.

Answer 1

Enthalpy of atomization is the amount of heat required for the formation of one mole of atoms in gaseous state from its element is known as heat of atomization of that element.

Complete step by step solution:
Transition metals are referred to the d-block elements of the periodic table; these are the elements that have incompletely filled d-orbital in its ground state or its oxidation states. It is the electronic configuration or the partially filled d and f orbital that set transition metals different from other elements.
Transition metals have high tensile strength, ductility, malleability and high thermal and electrical conductivity. With the exception of (Zn, Hg and Cd) they are quite hard and have a high melting and boiling point due to the involvement of greater number of electrons from (n-1)d in addition to the ns electrons in the interatomic metallic bonding.
The high enthalpy of atomization is due to the one unpaired electron per d-orbital that favors strong interatomic interaction. Hence we can conclude that greater the number of valence electrons greater is the enthalpy of atomization and stronger is the resultant metallic bonding. The elements with higher boiling point have higher enthalpy of atomization. It is also the reason accounting for better metal-metal bonding in compounds of the heavy transition metals.
Since the shielding effect of a d-electron is not that effective hence every new electron adds to d-orbital increasing the nuclear charge resulting in greater electrostatic attraction between nuclear charge and outermost electron causing the formation of strong metallic bonds that require high enthalpy of atomization. Hence all the above factors prove that enthalpies of atomization of transition metal is high

Note: The enthalpy of atomization is an important factor for deciding the standard electrode potential hence the metals that have high enthalpy of atomization tend to be noble in their reactions.