Question

$T{i}^{2+}$ is purple while $T{i}^{4+}$ is colourless, because :

• A. there is no crystal field effect in $T{i}^{4+}$
• B. $T{i}^{2+}$ has $d^2$ configuration
• C. $T{i}^{4+}$ has $d^2$ configuration
• D. $T{i}^{4+}$ is a very small cation as compared to $T{i}^{2+}$ and hence, does not absorb any light

Answer 1

Answer: (B)

$T{i}^{2+}$ has $d^2$ configuration

The ground state electronic configuration of $Ti\left(22\right):\left[Ar\right]4s^{2}3d^2$

For $T{i}^{2+}$ ion, the ground state electronic configuration is $\left[Ar\right]3d^2$.

It contains two unpaired electrons. Thus d-d transition is possible.

For $T{i}^{4+}$ ion, the ground state electronic configuration is $\left[Ar\right]3d^0$.
All the electrons are paired. Hence, d-d transition is not possible and it is colourless.