Q.12 The type of electronic transition responsible for the yellow colour of K2CrO4 is
(A) metal to ligand charge transfer
(B) ligand to metal charge transfer
(C) intra-ligand charge transfer
(D) d–d transition
Electronic Transition Responsible for Yellow Colour of K2CrO4
The colour of inorganic compounds depends on the type of electronic transition occurring
within the compound. A frequently asked chemistry question is to identify the
electronic transition responsible for the yellow colour of K2CrO4.
Let us understand this concept step by step.
Understanding the Compound
K2CrO4 contains the chromate ion (CrO42−).
Chromium is present in the +6 oxidation state.
Electronic configuration of Cr6+:
[Ar] 3d0
Since chromium has no d-electrons, d–d transitions are not possible.
Final Answer
Correct Option: (B) Ligand to Metal Charge Transfer
Conclusion
The yellow colour of K2CrO4 is due to
ligand to metal charge transfer (LMCT).
High oxidation state metals generally show intense colours
because of charge transfer transitions rather than d–d transitions.
