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The d & f Block Elements — Chemistry STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceChemistryThe d & f Block Elements3 Marks
Question
Give reasons for the following:
  1. Transition elements and their compounds act as catalysts.
  2. $E^0$ value for $\ce{(Mn^{2+}|Mn)}$ is negative whereas for $\ce{(Cu^{2+}|Cu)}$ is positive.
  3. Actinoids show irregularities in their electronic configuration.
✓

Answer

  1. Transition elements show catalytic property due to the presence of vacant orbitals that is why they have the tendency to form variable oxidation states. Hence, they can easily form intermediates with suitable reactants.
  2. $E^0$ value of $\ce{Cu^{2+}/ Cu}$ is positive that is why copper is least reactive metal among first transition metal this is because copper has the high enthalpy of atomization and enthalpy of ionization in comparison to $\ce{Mn^{2+}|Mn}$.
  3. This happens because of less energy difference between $5f, 6d$ and $7f$ subshell of actinides and hence electrons can easily be transferred from one subshell to another.

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