Transition and Inner Transition Elements — Chemistry STD 12 Science — Question
Maharashtra BoardEnglish MediumSTD 12 ScienceChemistryTransition and Inner Transition Elements4 Marks
Question
Why salts of $Sc^{3⊕}, Ti^{4⊕}, V^{5⊕}$ are colorless?
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Answer
(i) $S c^{3+}$ salts are colourless:
- The electronic configuration of ${ }_{21} Sc \left[ Ar \mid 3 d^1 4 s^2\right.$ and $Sc ^{3+}[ Ar ] d ^{\circ}$.
- Since there are no unpaired electrons in 3 d subshell, $d \rightarrow d$ transition is not possible.
- Therefore, $Sc ^{3+}$ ions do not absorb the radiations in the visible region. Hence salts of $Sc ^{3+}$ are colourless (or white).
(ii) $Ti ^{4+} \quad$ salts are colourless:
- The electronic configuration of $22 Ti [ Ar ] 3 d^2 4 s^2$ and $Ti ^{4+}$ : $[ Ar ] d ^{\circ}$
- Since there are no unpaired electrons in 3d subshell, d-*d transition is not possible.
- Therefore, $Ti ^{3+}$ ions do not absorb the radiation in visible region. Hence salts of $Ti ^{3+}$ are colourless.
(iii) $V s^{5+} \quad$ salts are eolourless :
- The electronic configuration of ${ }_{23} V$ : [Ar] $3 d^3 4 s^2$ and $V ^{5+}$ : [Ar] 3d
- Since there are no unpaired electrons in 3d-subshell, $d-d$ transition is not possible.
- Therefore, $V ^{5+}$ ions do not absorb the radiations in the visible region. Hence, $V ^{5+}$ salts are colourless, a
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