Name: The d-block Elements
Uploaded: 2019-07-19
Duration: 8 min 21 s
Description: The periodic table started with elements arranged in increasing order of Z. Now, it can tell us much more about an element. Watch this video to learn more.

Question

Give plausible reason for the fact that the transition metals have high enthalpy of atomisation.

Accepted Answer

Enthalpies of atomisation: Enthalpy of atomisation is the change in enthalpy when one mole of bonds is completely broken to obtain atoms in the gas phase. Transition elements have high effective nuclear charge and many valence electrons. Therefore, they form very strong metallic bonds. As a result, the enthalpy of atomization of transition metals is high.The metals of the second and third series have greater enthalpies of atomization than the corresponding elements of the first series. This is due to much more frequent metal bonding in compounds of heavy transition metals.

The transition metals have $n s^{1, 2} (n - 1) d^{1 - 10}$ Configuration. As the orbitals are filled the number of unpaired electrons increases the strong metallic bonding increases so the energy required to separate the solid metals into its atoms is more. From mid-transition series i.e. from chromium onwards, the number of proton increases in the nucleus and so is the nuclear charge on the coming electrons. This increases the pull of electrons and hence the energy of atomization.

Give plausible reason for the fact that the transition metals have high enthalpy of atomisation.

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