Question

Predict which of the following will be coloured in aqueous solution Ti²⁺ , V³⁺ , Sc⁴⁺ , Cu⁺ , SC³⁺ , Fe³⁺ , Ni²⁺ and CO³⁺.

Answer 1

Among Ti²⁺ , V³⁺ , Sc⁴⁺ , Cu⁺ , SC³⁺ , Fe³⁺ , Ni²⁺ and CO³⁺.in aqueous solution state. 

Ti (Z = 22) – Ti²⁺ – Electronic configuration is [Ar] 3d² V (Z = 23) – V³⁺ – Electronic configuration is [Ar] 3d² Sc (Z = 21) – SC⁴⁺ – Electronic configuration is [Ar] 1s² 2s² 2p⁶ 3s² 3p⁵ 

Cu (Z = 29) – Cu⁺ – Electronic configuration is [Ar] 3d¹⁰ 

Sc (Z = 21) – SC³⁺ – Electronic configuration is [Ar] 3d°4s° 

Fe (Z = 26) – Fe³⁺ – Electronic configuration is [Ar] 3d⁵

Ni (Z = 28) – Ni²⁺ – Electronic configuration is [Ar] 3d⁵

CO (Z = 27) – CO³⁺ – Electronic configuration is [Ar] 3d⁶

A transition metal ion is coloured if it has one or more unpaired electrons in (n-l)d orbital, i.e. 3d orbitals in the case of first transition series, when such species are exposed to visible radiation, d – d transition take place and the species are coloured.

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