All of the following statements concerning crystal field theory are true EXCEPT
a. in low-spin complexes, electrons are concentrated in the dxy, dyz, and dxz orbitals.
b. in an isolated atom or ion, the five d orbitals have identical energy.
c. low-spin complexes contain the maximum number of unpaired electrons.
d. the crystal field splitting is larger in low-spin complexes than high-spin complexes.
e. the energy difference between d orbitals often corresponds to an energy of visible light.
Answer C
I agree
c. low-spin complexes contain the maximum number of unpaired electrons.
In low-spin complexes, the electrons are paired as much as possible, resulting in the formation of high-spin complexes with fewer unpaired electrons.
To answer this question, we need to evaluate each statement and determine if it is true or false. The one statement that is false is the correct answer.
a. In low-spin complexes, electrons are concentrated in the dxy, dyz, and dxz orbitals.
This statement is true. In low-spin complexes, the energy difference between the t2g (dxy, dyz, and dxz) and eg (dx2-y2 and dz2) orbitals is large. Therefore, the electrons preferentially occupy the lower energy t2g orbitals, leading to a low-spin configuration.
b. In an isolated atom or ion, the five d orbitals have identical energy.
This statement is true. In an isolated atom or ion, the d orbitals have the same energy. However, in a crystal field, this degeneracy is lifted, leading to different energies for the d orbitals.
c. Low-spin complexes contain the maximum number of unpaired electrons.
This statement is false. Low-spin complexes have fewer unpaired electrons than high-spin complexes. In a low-spin complex, the electrons are paired up in the lower energy t2g orbitals, resulting in a maximum of two unpaired electrons. On the other hand, high-spin complexes have unpaired electrons in the higher energy eg orbitals.
d. The crystal field splitting is larger in low-spin complexes than high-spin complexes.
This statement is true. In low-spin complexes, the energy difference between the t2g and eg orbitals is large, resulting in a large crystal field splitting. In high-spin complexes, the energy difference between the t2g and eg orbitals is small, leading to a small crystal field splitting.
e. The energy difference between d orbitals often corresponds to an energy of visible light.
This statement is true. The energy difference between the d orbitals in crystal field theory can correspond to the energy of visible light. This is why transition metal complexes often exhibit colors. The absorbed light excites electrons from the lower energy d orbitals to the higher energy d orbitals, and the energy difference determines the color observed.
Therefore, the correct answer is C, as it is the only false statement among the given options.