Short Answer TypeExplain giving reasons:
(i) Transition metals and their compounds generally exhibit a paramagnetic behaviour.
(ii) The chemistry of actinoids is not as smooth as that of lanthanoids.Complete the following chemical equations:
Or
State reasons for the following:
(i) Cu (I) ion is not stable in an aqueous solution.
(ii) Unlike Cr3+, Mn2+, Fe3+ and the subsequent other M2+ ions of the 3d series of elements, the 4d and the 5d series metals generally do not form stable cationic species.
(i) In aqueous solution, Cu+ ion undergoes oxidation to Cu2+ ion. The relative stability of different oxidation states can be seen from their electrode potentials.
Cu+(aq) + e- --> Cu(s) , E0red = 0.52V
Cu2+(aq) + 2e- ---> Cu(s), E0red = 0.34V
Thus overall reaction is :
2Cu+ (aq) ---> Cu2+ (aq) + Cu(s)
Due to more reduction electrode potential value of Cu+, it undergoes oxidation reaction quite feasibly. Hence, copper (I) ion is not stable in aqueous solution.
(ii) The valence shell electronic configurations of Cr3+, Mn2+, Fe3+ are d3, d5 and d3respectively. Owing to the symmetrical distribution of the d electrons, these ions can form stable cationic complexes. The atomic radii of the 4d and 5d transition elements are more than that of the 3d series elements. Hence, generally, they do not form stable cationic species.
Long Answer Type(a) Complete the following equations :
(i) Cr2O72- + 2OH- --->
(ii) MnO4- + 4H+ + 3e- --->
(b) Account for the following :
(i) Zn is not considered as a transition element.
(ii) Transition metals form a large number of complexes.
(iii) The E° value for the Mn3+/Mn2+ couple is much more positive than that for Cr3+/Cr2+ couple.
OR
(i) With reference to structural variability and chemical reactivity, write the differences between lanthanoids and actinoids.
(ii) Name a member of the lanthanoid series which is well known to exhibit +4 oxidation state.
(iii) Complete the following equation :
MnO4- + 8H+ + 5e---->
iv) Mn3+ is more paramagnetic than Cr3+.
Short Answer TypeWrite the formula of an oxo-anion of Manganese (Mn) in which it shows the oxidation state equal to its group number.
Account for the following :
Transition metals form large number of complex compounds.
Account for the following :
The lowest oxide of transition metal is basic whereas the highest oxide is
amphoteric or acidic.
Account for the following :
E° value for the Mn3+/Mn2+ couple is highly positive (+1.57 V) as compared to Cr3+/Cr2+.
Write one similarity and one difference between the chemistry of lanthanoid and actinoid elements.
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