CBSE Class 12 · 2004 · Foreign · d and f Block ElementsShort Answer

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The outer electronic configurations of two transition metals are (i) 3d⁵4s² and (ii) 3d⁶4s² respectively. From this information predict the relative stability of the +2 and +3 oxidation states of these metals. Which of the two exhibits the larger number of oxidation states?

Solution

(i) 3d

^{5}

^{2}

(manganese): M

^{2 +}

has the half-filled 3d

^{5}

configuration — very stable; M

^{3 +}

(3d

^{4}

) loses that stability, so +2 ≫ +3 (Mn

^{3 +}

is strongly oxidising).
(ii) 3d

^{6}

^{2}

(iron): M

^{3 +}

attains 3d

^{5}

(half-filled, stable) while M

^{2 +}

is 3d

^{6}

; hence +3 is the more stable state for iron.
Larger range of oxidation states: metal (i), Mn — with 5 unpaired d electrons plus 2 s electrons it shows every state from +2 to +7.

CBSE Class 12 Board · 2004 · Foreign · Subjective

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CBSE Class 12 · 2004 · Foreign · d and f Block ElementsShort Answer

Solution

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