d and f Block Elements — CBSE Class 12 · 2016 · All India Board Question with Solution

The elements of the 3d transition series are given as:
Sc Ti V Cr Mn Fe Co Ni Cu Zn
Answer the following:
i) Write the element which is not regarded as a transition element. Give a reason.
ii) Which element has the highest melting point?
iii) Write the element which can show an oxidation state of +1.
iv) Which element is a strong oxidising agent in the +3 oxidation state, and why?

Solution

(i) Zinc. Zn ([Ar]3d

^{10}

^{2}

) and its only ion Zn

^{2 +}

(3d

^{10}

) both have a completely filled d-subshell, so Zn does not meet the definition of a transition element.
(ii) Chromium — with the maximum number of unpaired d electrons (3d

^{5}

^{1}

) its metallic bonding is strongest, giving the highest melting point of the series (≈ 2180 K).
(iii) Copper — [Ar]3d

^{10}

^{1}

loses its single 4s electron to give Cu

^{+}

(stable 3d

^{10}

), so Cu shows +1.
(iv) Mn

^{3 +}

is a strong oxidant: on gaining an electron it becomes Mn

^{2 +}

with the exactly half-filled, extra-stable 3d

^{5}

configuration, so the reduction is strongly favoured (E° = +1.57 V).

CBSE Class 12 Board · 2016 · All India · Subjective

CBSE Class 12 · 2016 · All India · d and f Block ElementsLong Answer

Solution

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