Problem 48 - Chemistry The Central Science In Si Units

Question

Give examples of transition metal ions with +3 charge that have an electron configuration of \(n d^{5}(n=3,4,5 \ldots)\).

Step-by-Step Solution

Answer

Mn\(^{3+}\), Tc\(^{3+}\), and Re\(^{3+}\) have \(d^5\) configurations.

Step 1: Understanding the Problem

We are asked to find transition metal ions with a +3 charge and an electron configuration of \( nd^5 \), where \( n \) can be 3, 4, 5, etc. The aim is to identify transition metals when they lose three electrons and achieve a \( d^5 \) configuration.

Step 2: Reviewing Transition Metal Properties

Transition metals are characterized by having partially filled \( d \) orbitals. When forming ions, they typically lose electrons from the \( s \) orbital first, followed by the \( d \) orbital. For an electron configuration \( nd^5 \), we need to identify metals where removing three electrons results in this configuration.

Step 3: Solve for \( n = 3 \)

For \( n = 3 \), the d-block starts with Scandium (\([Ar]3d^1 4s^2\)). We need a metal whose neutral atom has three more electrons (than 5) in its 3d orbitals. Manganese (Mn, \([Ar]3d^5 4s^2\)) fits because when it forms Mn\(^{3+}\), it loses the two 4s electrons and one 3d electron, resulting in \(3d^5\).

Step 4: Solve for \( n = 4 \) and \( n = 5 \)

For \( n = 4 \), consider elements like Technetium (Tc, \([Kr]4d^5 5s^2\)), which would form Tc\(^{3+}\) with configuration \(4d^5\). For \( n = 5 \), Rhenium (Re, \([Xe]5d^5 6s^2\)) forms Re\(^{3+}\) resulting in \(5d^5\) configuration.

Key Concepts

Electron Configuration

The electron configuration of an element describes the distribution of electrons in the atomic orbitals. Atoms aim for the lowest energy state, meaning electrons occupy the available orbitals starting from the lowest energy level.

• Electron configurations are written in a sequence that shows which orbitals are filled.
• The notation combines the energy level, subshell (e.g., s, p, d, f), and the number of electrons in that subshell, like in the example: \([Ar]3d^5 4s^2\).
• The placement of electrons follows rules such as the Aufbau principle, which dictates the order of filling from low to high energy.

In transition metals, the d subshell plays a crucial role. As you move from left to right across the periodic table, electrons are added to the d orbitals. These d electrons are responsible for a wide range of chemical behaviors.
The exchange and removal of electrons in transition metals influence their oxidation states and magnetic properties.

Transition Metal Ions

Transition metals are unique because they can form ions that have multiple possible oxidation states. This flexibility is influenced by their electron configuration, especially from the d orbitals.

• In the formation of ions, transition metals typically lose electrons starting from the outermost s orbital, then proceed with d electrons if necessary.
• This is due to the fact that the energy level of the s subshell is slightly higher than that of the d subshells once filled, making s electrons easier to remove.

For example, manganese, with a configuration of \([Ar]3d^5 4s^2\), when forming Mn\(^{3+}\), loses two electrons from the 4s orbital and one electron from the 3d.
As a result, it achieves a \([Ar]3d^4\) configuration for its ion, which illustrates why transition metals can form ions with varying charges.

+3 Charge Transition Metals

When it comes to transition metals with a +3 charge, the ion configuration often results in stable half-filled or filled d subshells.

• The stability of a half-filled or full d subshell contributes to the stability of +3 charged transition metal ions.
• Examples include manganese (Mn), technetium (Tc), and rhenium (Re), which have configurations \([Ar]3d^5\), \([Kr]4d^5\), and \([Xe]5d^5\) respectively when they form +3 ions.

These configurations suggest that after losing three electrons, the ions achieve a balanced distribution in their d subshell, aiding in chemical stability.
This characteristic of achieving a \(`nd^5`\) configuration with a +3 charge is a key aspect of transition metal chemistry.