Determine the number of unpaired electrons expected for...

Key Concepts

Crystal Field Theory

Crystal field theory explains how the approach of ligands causes the degenerate d orbitals of a transition metal ion to split into groups of different energies. This splitting influences the electronic arrangement within the d orbitals and ultimately determines magnetic and spectroscopic properties, such as the number of unpaired electrons.

Ligand Field Strength

Ligand field strength describes how strongly a ligand interacts with the metal ion, affecting the degree of d orbital splitting. Strong field ligands produce larger splitting, which can lead to low-spin configurations where electrons are forced to pair in lower-energy orbitals, while weak field ligands result in smaller splitting, favoring high-spin configurations with more unpaired electrons.

High-Spin vs Low-Spin Configurations

The concepts of high-spin and low-spin complexes result from the competition between the crystal field splitting energy and the electron pairing energy. In high-spin complexes, the splitting is small relative to the pairing energy, leading to maximal unpaired electrons. In contrast, low-spin complexes have a large splitting, and electrons pair up in the lower energy orbitals, resulting in fewer unpaired electrons.

Oxidation State and d Electron Count

The oxidation state of the metal determines the number of d electrons present in the complex, which is essential when applying crystal field theory. Knowing the d electron count allows one to distribute the electrons among the split d orbitals according to Hund’s rules and the pairing energy considerations, thereby predicting the number of unpaired electrons.

Transcript

00:03 All right, so in this video, we want to determine the number of unpaired electrons using the crystal field theory in this complex.

00:16 So the first one is this complex of iron.

00:21 So first of all, we need to know the charge of iron.

00:25 Which type of ion is it? is it iron 2 or iron 3? all right so to determine the oxidation state of iron here we have this nitrite which is minus one all right and we have six of them so if we say ion is x so x plus minus 1 times 6 because minus 3 so definitely x because it costs plus three right so it is ion three so ion three means the ion lost three electrons now we need to know the ground stage electron configuration for iron iron is again then for four is 2, 3d6.

01:39 All right.

01:42 So if it lost three electrons, three of these electrons are gone.

01:46 Okay.

01:47 So i am 3 is 3d3.

02:00 So we are determining the number of d orbital electrons.

02:05 Okay.

02:06 Now according to the crystal field theory, the d orbiter splits into two.

02:12 And the splatine could be strong field or weak field.

02:19 Now, whether strong field or weak field, it depends on the ligands.

02:25 Okay, it depends on the ligands.

02:27 Now, the ligands, we have a list of ligands.

02:32 We have what you call spectral chemical series.

02:36 We have c.

02:38 This is cyanide.

02:41 You have n02 minus and ethylene thyme ammonia and hydroxide bromide iodide okay so when you're on the left side here's a strong field on the right hand side is weak field all right so there's strong field means there's a large gap between the split in the split the orbitals okay yeah so the nitride iron is strong filled so the d orbital of iron are split with a large gap so we have you have t 2g here then we have e g all right there's a large gap between now the deorbital we have only we have three electrons...

Please give Ace some feedback