Specify the number of unpaired electrons in CoF₆³^- (weak field).

Question

Quizplus · Accepted Answer

To determine the number of unpaired electrons in the given complex, we first need to write down the electronic configuration of each element involved.

Co: [Ar] 3d7 4s2 
F: 1s2 2s2 2p5 
S: 1s2 2s2 2p6 3s2 3p4 
P: 1s2 2s2 2p6 3s2 3p3

The ligands in the complex are S and F, both of which are weak field ligands. Therefore, we can assume that the cobalt ion is in high spin configuration, where the electrons will fill the 4d orbitals before pairing up in the 3d orbitals.

The electron configuration of Co(II) in this complex can be written as: [Ar] 3d6.

Now, we can begin to fill in the electrons from the ligands. Each S ligand contributes two electrons, one from its 3s orbital and one from its 3p orbital, for a total of 2 x 2 = 4 electrons. Each F ligand contributes one electron from its 2p orbital. There are three F ligands in this complex, so the total number of electrons contributed by F ligands is 3 x 1 = 3. Finally, the entire complex has a charge of -1, so we add one more electron to the electron count.

Total number of electrons: 
6 (Co) + 4 (S) + 3 (F) + 1 (charge) = 14 electrons

Now, we need to fill up the orbitals with the electrons. We can use an energy level diagram to do this. The d orbitals are split into two groups, with the lower energy group t2g and the higher energy group eg.

Energy level diagram: 
t2g: ↑↓ ↑↓ ↑↓ 
eg: ↑ ↑ ↑

The arrows represent the electrons, and the up and down arrows indicate the spin of each electron. Since we have 6 electrons in the d orbitals, they will fill up the t2g orbitals first. This leaves 2 electrons unpaired in the eg orbitals.

Therefore, the answer is A) 4 unpaired electrons.

Specify the Number of Unpaired Electrons in CoF63- (Weak Field)

Specify the Number of Unpaired Electrons in CoF₆³^- (Weak Field)