It seems that you have missed quite a few key points while explaining your question. Firstly, Hg is a d-block element which is not considered to be a transition element since it has complete d-orbital. The same holds for other members of the group like Zn and Cd Also, the statement that complexes containing fully filled d-orbitals are not coloured is incorrect. Here's my explanation:
Colour of compounds and complexes containing transition elements may be due to two reasons: d-d transitions and charge transfer.
d-d transition is the point that your book seems to be talking about. But that is not the reason why HgI2 is coloured. The actual reason for the colour is charge transfer. Charge transfer occurs when the compound has a high covalent character. This occurs when the anion is highly polarisable and can distort its electron cloud easily. $I^{-}$ has very high polarisability which results in the anionic charge getting easily transferred to the $Hg^{2+}$ cation. This process releases some energy which falls in the visible spectrum. Hence we can say that compounds like KMnO4, HgI2, etc. are coloured.
It seems that you have missed quite a few key points while explaining your question. Firstly, Hg is a d-block element which is not considered to be a transition element since it has complete d-orbital. The same holds for other members of the group like Zn and Cd Also, the statement that complexes containing fully filled d-orbitals are not coloured is incorrect. Here's my explanation:
Colour of compounds and complexes containing transition elements may be due to two reasons: d-d transitions and charge transfer.
d-d transition is the point that your book seems to be talking about. But that is not the reason why HgI2 is coloured. The actual reason for the colour is charge transfer. Charge transfer occurs when the compound has a high covalent character. This occurs when the anion is highly polarisable and can distort its electron cloud easily. $I^{-}$ has very high polarisability which results in the anionic charge getting easily transferred to the $Hg^{2+}$ cation. This process releases some energy which falls in the visible spectrum. Hence we can say that compounds like KMnO4, HgI2, etc. are coloured.
It seems that you have missed quite a few key points while explaining your question. Firstly, Hg is a d-block element which is not considered to be a transition element since it has complete d-orbital. The same holds for other members of the group like Zn and Cd Also, the statement that complexes containing fully filled d-orbitals are not coloured is incorrect. Here's my explanation:
Colour of compounds and complexes containing transition elements may be due to two reasons: d-d transitions and charge transfer.
d-d transition is the point that your book seems to be talking about. But that is not the reason why HgI2 is coloured. The actual reason for the colour is charge transfer. Charge transfer occurs when the compound has a high covalent character. This occurs when the anion is highly polarisable and can distort its electron cloud easily. $I^{-}$ has very high polarisability which results in the anionic charge getting easily transferred to the $Hg^{2+}$ cation. This process releases some energy which falls in the visible spectrum. Hence we can say that compounds like KMnO4, HgI2, etc. are coloured.
Hope it helps!
It seems that you have missed quite a few key points while explaining your question. Firstly, Hg is a d-block element which is not considered to be a transition element since it has complete d-orbital. The same holds for other members of the group like Zn and Cd Also, the statement that complexes containing fully filled d-orbitals are not coloured is incorrect. Here's my explanation:
Colour of compounds and complexes containing transition elements may be due to two reasons: d-d transitions and charge transfer.
d-d transition is the point that your book seems to be talking about. But that is not the reason why HgI2 is coloured. The actual reason for the colour is charge transfer. Charge transfer occurs when the compound has a high covalent character. This occurs when the anion is highly polarisable and can distort its electron cloud easily. $I^{-}$ has very high polarisability which results in the anionic charge getting easily transferred to the $Hg^{2+}$ cation. This process releases some energy which falls in the visible spectrum. Hence we can say that compounds like KMnO4, HgI2, etc. are coloured.
Hope it helps!
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