Question

How many unpaired electrons would you expect for the complex ion: [Fe(NH₃)₆]₂ ?

O 2
O 6
O 4
O 5
O 0

Answer 1

For the complex ion [Fe(NH₃)₆]²+, which contains a weak field ligand (NH₃), there are expected to be four unpaired electrons. This conclusion is based on the crystal field theory considering NH₃ causes a small crystal field splitting, and thus the complex behaves as a high-spin complex.

Step-by-step explanation:

The question is asking about the number of unpaired electrons you would expect for the complex ion [Fe(NH₃)₆]²+. To determine the number of unpaired electrons in this complex, which is relevant to its magnetic properties, one must consider the crystal field theory.

For the [Fe(NH₃)₆]²+ complex, NH₃ is generally considered a weak field ligand, which would result in a small crystal field splitting energy (Aocthigh-spin complex, similar to [Fe(H₂O)₆]²+, because it is more energetically favorable for the d electrons to remain unpaired and occupy the higher energy eg orbitals rather than pair up in the lower energy t2g orbitals. Since the Fe center in this complex is in the +2 oxidation state (Fe²+), it would typically have six d electrons. Following a high-spin configuration, these six electrons would occupy the five 3d orbitals singly, resulting in four unpaired electrons (one pair of electrons will be present).

Answer 2

The complex ion [Fe(NH₃)₆]²⁺ has four unpaired electrons. Option 3) 4 is the correct answer.

To determine the number of unpaired electrons in the complex ion [Fe(NH₃)₆]²⁺, we need to consider the electronic configuration of the central iron (Fe) atom and the ligands (NH₃) surrounding it.

Iron (Fe) has an atomic number of 26, indicating that it has 26 electrons. The electronic configuration of Fe in its ground state is [Ar] 3d⁶ 4s². In the complex ion, Fe is in the +2 oxidation state, which means it loses two electrons from its outermost 4s² orbital.

Now, let's consider the ligands NH₃. Each NH₃ ligand has a lone pair of electrons, which can form a coordinate bond with the Fe ion. Since there are six NH₃ ligands in the complex, we have a total of six lone pairs available for bonding.

In a complex, the central metal ion can use its d orbitals to form bonding and non-bonding electron pairs. The number of unpaired electrons in the complex is determined by the number of d orbitals that are not involved in bonding with the ligands.

In the case of [Fe(NH₃)₆]²⁺, the Fe²⁺ ion has four unpaired electrons. This is because the Fe²⁺ ion has a d⁶ electronic configuration, and the six available d orbitals are occupied by six electrons from the NH₃ ligands, leaving four unpaired electrons.