Question

explain why TiO2 is white but TiCl3 is coloured. the atomic number of Ti is 22.

Answer 1

Explanation:

Atomic number of titanium is 22 and its electronic configuration is $4s^{2}3d^{2}$.

Electronic configuration of $Ti^{2+}$ is $4s^{0}3d^{2}$. Since there are no unpaired electrons, therefore, $TiO_{2}$ molecule is white in color.

Whereas electronic configuration of $Ti^{3+}$ is $4s^{0}3d^{1}$. Since there is one unpaired electron, therefore, $TiCl_{3}$ is coloured.

Answer 2

"$TiO_2$is white but $TiCl_3$ is coloured because no unpaired electron in $TiO_2$ and presence of the unpaired electron in $TiCl_3$.

This unpaired electrons in $TiCl_3$ take part in excitation and violet colour is transmitted.

Explanation:

We know that the atomic number of Titanium is 22.

The electronic configuration of Titanium is given as $4s^23d^2$

The oxidation state of Titanium in $TiO_2 is Ti^(2+).$ The electronic configuration of $Ti^{(2+)} is 4s^03d^2.$ All the "electrons are paired" and there is no unpaired electrons. No excitation of electrons occurs. Hence, $TiO_2$ is colourless.

Whereas the oxidation state of Titanium in $TiCl_3 is Ti^3+$ and the electronic configuration of $Ti^3+ is 4s^03d^1$. The d-orbital contains one unpaired electron. When light falls on $Ti^3+$ complex, the excitation of electrons from$t_(2g) level \quad to\quad e_g$ level occurs. The "excitation" takes place in greenish yellow region and violet colour is transmitted. This "transition" is called "d-d transition"."