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14. Which of the following trivalent
lanthanide ions is not coloured?
*(a) Er3+
(b) Yb3+ Sofeu
(d) Sm3+
3+
стои право
not colourat- no
(c) Pm3+
Answers
Answer:
check electronic configuration
if electrons are paired then no transition and no colour
if electeons are not laired then it shows colour
Complete question:
Which of the following trivalent lanthanoid ions is not coloured?
(a) Lu⁺³
(b) Pm⁺³
(c) Sm⁺³
(d) Eu⁺³
Answer:
Lu⁺³ ion has no colour.
Explanation:
(a) Electronic configuration of Lutetium (Lu) (Z = 71): [Xe]4f¹⁴ 5d¹ 6s²
Electronic configurationof Lu⁺³ (Z = 68): [Xe] 4f¹⁴
As it has completely filled sub-shell (f) it is hard to excite the electron present in the Lu⁺³ ion.
Therefore, the ion Lu⁺³ does not show any colour.
(b) Electronic configuration of Promethium (Pm) (Z = 61): [Xe]4f⁵ 6s²
Electronic configurationof Pm⁺³ (Z = 58): [Xe] 4f⁴
As it has incomplete filled sub-shell (f) it is easy to excite the electron present in the Pm⁺³ ion.
Therefore, the ion Pm⁺³ shows pink colour.
(c) Electronic configuration of Samarium (Sm) (Z = 62): [Xe]4f⁶ 6s²
Electronic configurationof Sm⁺³ (Z = 59): [Xe] 4f⁵
As it has incomplete filled sub-shell (f) it is easy to excite the electron present in the Sm⁺³ ion.
Therefore, the ion Sm⁺³ shows yellow colour.
(d) Electronic configuration of Euporium (Eu) (Z = 63): [Xe]4f⁷ 6s²
Electronic configurationof Eu⁺³ (Z = 68): [Xe] 4f⁶
As it has incomplete filled sub-shell (f) it is a bit easy to excite the electron present in the Eu⁺³ ion.
Therefore, the ion Eu⁺³ shows pink colour.
Hence, Lu⁺³ ion is colourless.
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