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The D-And-f-Block Elements

Question

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Explain the following facts:
Transition metals acts as catalyst.

Solution

Transition metals acts as catalyst due to the following reasons:

(i) Their partially empty d-orbitals provide surface area for reactant molecules.

(ii) They combine with reactant molecules to form transition states and lowers their activation energy.

(iii) They show multiple oxidation states and by giving electrons to reactants they form complexes and lower their energies.

Some More Questions From The d-And-f-Block Elements Chapter

In the series Sc (Z = 21) to Zn(Z = 30), the enthalpy of atomisation of zinc is the lowest i.e., 26, kJ mol. Why?

The E° (M²⁺/M) value for copper is positive (+ 0.34 V). What is possibility the reason for this?

How would you account for the irregular variation of ionisation enthalpies (first and second) in the first series of the transition elements?

Why is the highest oxidation state of a metal exhibited in its oxide or fluoride only?

Which is a stronger reducing agent Cr²⁺ or Fe²⁺ and why?

Explain why Cu⁺ ion is not stable in aqueous solutions?

Actinoid contraction is greater from element to element than lanthanoid contraction. Why?

On what ground can you say that scandium (Z = 21) is a transition element but zinc (Z = 30) is not?

The outer electronic configuration of copper is 3d¹⁰ 4s¹, yet it is considered transition element. Why?

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