Question
Why is $Sc^3+$ colourless while $Ti^3+$ coloured? $($Atomic number $Sc = 21, Ti = 22).$
✓
Answer
$Ti^{3+}$ is a $3d^1$ system. The colour is due to $d–d$ transition. There is one $d$ electron present in the $3d$ subshell. When light falls on the $Ti^{3+}$ complex, the $t_{2g}$ electron is excited to the eg level. This excitation takes place in the greenish yellow region $(≈5000 A^\circ )$ and the rest is transmitted. The complementary colour is transmitted which is violet.
$Sc^{3+}$ is a $3d^0$ system. There are no $d$ electrons; hence, $d–d$ transition is not possible. Hence, $Sc^{3+}$ is colourless.
$Sc^{3+}$ is a $3d^0$ system. There are no $d$ electrons; hence, $d–d$ transition is not possible. Hence, $Sc^{3+}$ is colourless.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
What are different units of energy and work ?
How do half lives of the fist order and zero order reactions change with initial concentration of reactants?
What is the action of the following on carboxylic acid:
(i) SOCI₂ (ii) P₂O₃?
(i) SOCI₂ (ii) P₂O₃?
What are the units for rate constants for zero order and second order reactions if time is expressed in seconds and concentration of reactants in $mol / L$ ?
→Write a note on Friedel Craft’s acylation.
Write the rate law for the following reactions:
(a) A reaction that is zero order in $A$ and second order in $B$.
(b) A reaction that is second order in $NO$ and first order in $Br _2$.
→(a) A reaction that is zero order in $A$ and second order in $B$.
(b) A reaction that is second order in $NO$ and first order in $Br _2$.
Derive the relationship between $pH$ and $pОН.$
→Define the following:
a. Atom economy.
a. Atom economy.
Explain the action of chromic acid on phenol.###How is phenol converted into benzoquinone?
Give examples to show that elements of first row of d-block elements differ from second and third row with respect to the stabilisation of higher oxidation states.