Problem 48 - Chemistry: The Central Science in SI Units, Global Edition

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

The transition metal ions with +3 charge that have an electron configuration of the form nd^5 are: 1. Mn^3+ (Manganese) with an electron configuration of [Ar] \(3d^5\). 2. Tc^3+ (Technetium) with an electron configuration of [Kr] \(4d^5\). 3. Re^3+ (Rhenium) with an electron configuration of [Xe] \(5d^5\).

Step 1: Identify the electron configuration of the neutral transition metal atoms

Before looking for the ions, it is necessary to determine the electron configurations for neutral transition metal atoms. In this case, we need the metal atoms that have their highest energy electrons in the d orbitals and follow the order of the periodic table.

Step 2: Determine the +3 charged ions' electron configurations

Now that we know the electron configurations of the transition metal atoms, we'll consider their ions with a +3 charge by removing three electrons. This will result in nd^5 configuration with n being equal to 3, 4, 5, etc.

Step 3: Identify the metal ions of interest

After removing three electrons to result in the required nd^5 configuration, we can identify which metal ions have the desired electron configuration. A few examples are provided below: 1. For n = 3, \(3d^5\), Mn^3+ ion (Manganese): In a neutral Mn (Manganese) atom, the electron configuration is [Ar] \(4s^23d^5\). Upon losing three electrons, Mn becomes Mn^3+ with an electron configuration of [Ar] \(3d^5\). 2. For n = 4, \(4d^5\), Tc^3+ ion (Technetium): In a neutral Tc (Technetium) atom, the electron configuration is [Kr] \(5s^24d^5\). Upon losing three electrons, Tc becomes Tc^3+ with an electron configuration of [Kr] \(4d^5\). 3. For n = 5, \(5d^5\), Re^3+ ion (Rhenium): In a neutral Re (Rhenium) atom, the electron configuration is [Xe] \(6s^25d^5\). Upon losing three electrons, Re becomes Re^3+ with an electron configuration of [Xe] \(5d^5\). These are examples of transition metal ions with +3 charge and electron configurations of the form nd^5 where n is equal to 3, 4, and 5 respectively.

Key Concepts

Electron Configuration

Understanding electron configuration is crucial in chemistry because it explains how electrons are distributed in an atom's orbitals. Each element has a unique electron configuration, which follows the arrangement of electrons in shells and subshells based on increasing energy levels. Electrons fill subshells in a specific order, starting from the lowest energy level:

• s (2 electrons)
• p (6 electrons)
• d (10 electrons)
• f (14 electrons)

In transition metals, electrons fill the d subshells last after s subshells, despite s being lower in energy. This sometimes leads to unique electron configurations compared to other elements. When forming ions, electrons are typically removed from the outermost subshell first. For transition metals, this often means removing electrons from the s orbitals before the d orbitals, which is vital to understand when dealing with charged ions like the +3 transition metal ions discussed here.

Manganese Ion (Mn^3+)

Manganese (Mn) is a transition metal known for its various oxidation states, with Mn^3+ being one of them. To comprehend the electron configuration of Mn^3+, start with neutral manganese. It has an electron configuration of [Ar] 4s^2 3d^5. In its +3 oxidation state, manganese loses three electrons. Observing the rule that electrons are first removed from the outermost shell, we remove two electrons from the 4s orbital and one from the 3d orbital, leaving Mn^3+ with an electron configuration of [Ar] 3d^5.

This configuration results in a half-filled d subshell, which is relatively stable due to its symmetric distribution of electrons. Understanding this stability helps explain why certain oxidation states are more prevalent in chemistry. Manganese ions often play critical roles in biological systems and are a key component in enzymes and other molecular structures.

Technetium Ion (Tc^3+)

Technetium (Tc) is a somewhat unique transition metal because all its isotopes are radioactive. Despite this, it still follows the expected electron configuration for transition metals. A neutral technetium atom has the configuration [Kr] 5s^2 4d^5.

When forming the Tc^3+ ion, three electrons are lost. Consistent with rules for electron removal, two electrons are removed from the 5s orbital and one from the 4d orbital. Thus, Tc^3+ has the electron configuration [Kr] 4d^5.

Like manganese, technetium in the +3 oxidation state results in a half-filled d subshell, which contributes to its relative stability. Understanding Tc's properties helps scientists in fields such as nuclear medicine, where it is used in diagnostic imaging. Knowing the electron configuration allows chemists to predict and explain these and other behaviors in chemical reactions and formations.

Rhenium Ion (Re^3+)

Rhenium (Re) represents another fascinating example in the study of transition metals. Its electron configuration in the neutral state is [Xe] 6s^2 5d^5. In forming a +3 charged ion, three electrons are removed to achieve its ionized state.

Electrons are first removed not from the d orbital, but from the s orbital due to their higher principal quantum number, 6s. Thus, the Re ion loses two electrons from the 6s orbital and one from the 5d orbital, resulting in Re^3+ with an electron configuration of [Xe] 5d^5.

This half-filled d subshell bestows Re^3+ ions with additional stability, akin to other ions with nd^5 configurations. In industrial applications, rhenium is admired for its high melting points and use in high-temperature superalloys. Its electron configuration helps ensure these properties by influencing its chemical stability and bonding patterns.