Account for the following/Explain why :(i) Transition metals exhibit v

1.	Account for the following/Explain why :(i) Transition metals exhibit variable oxidation states,(ii) Zr (Z = 40) and Hf (Z = 72) have almost identical radii,(iii) Transition metals and their compounds act as a catalyst
Answer» (i) In transition elements, the energies of (n – 1) d orbitals and ns orbitals are nearly same. Therefore, electrons from both can participate in bond formation and hence show variable oxidation states. (ii) This is because of filling of 4f orbitals which have poor shielding effect (lanthanoid contraction). (iii) Due to the following reasons : (a) Transition metal form unstable intermediate compounds because of their variable oxidation states and give a new path with lower activation energy for the reaction. (b) They provide large surface area with free valencies on which reactants are adsorbed.

Account for the following/Explain why :(i) Transition metals exhibit variable oxidation states,(ii) Zr (Z = 40) and Hf (Z = 72) have almost identical radii,(iii) Transition metals and their compounds act as a catalyst

Answer»

(i) In transition elements, the energies of (n – 1) d orbitals and ns orbitals are nearly same. Therefore, electrons from both can participate in bond formation and hence show variable oxidation states.

(ii) This is because of filling of 4f orbitals which have poor shielding effect (lanthanoid contraction).

(iii) Due to the following reasons :

(a) Transition metal form unstable intermediate compounds because of their variable oxidation states and give a new path with lower activation energy for the reaction.

(b) They provide large surface area with free valencies on which reactants are adsorbed.

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