Problem 54 - Chemistry and Chemical Reactivity

Question

Two elements in the second transition series ( \(Y\) through Cd) have four unpaired electrons in their \(3+\) ions. What elements fit this description?

Step-by-Step Solution

Answer

The elements are Molybdenum (Mo) and Technetium (Tc).

Step 1: Identify the Second Transition Series

The second transition series consists of elements from Yttrium (\(Y\)) to Cadmium (\(Cd\)). These elements fill the 4d subshell in the periodic table.

Step 2: Determine the Electron Configuration of the Neutral Atoms

List the electron configurations of the neutral atoms. For example, \(Y: [Kr] 4d^1 5s^2\), \(Zr: [Kr] 4d^2 5s^2\), \(Nb: [Kr] 4d^4 5s^1\), etc.

Step 3: Consider the Ionization Process to Form 3+ Ions

In the formation of \(3^+\) ions, three electrons are removed, typically from the outermost \(s\) and \(d\) orbitals.

Step 4: Calculate the 3+ Ion Configuration

Remove three electrons from each element: from the \(s\) and then the \(d\) subshells if needed. For example, \(Y^{3+}: [Kr] 4d^0\), \(Zr^{3+}: [Kr] 4d^1\), \(Nb^{3+}: [Kr] 4d^2\), etc.

Step 5: Identify Elements with Four Unpaired Electrons

Check the ions to see which have four unpaired electrons. \(Mo^{3+}\) with configuration \([Kr] 4d^3\) and \(Tc^{3+}\) with \([Kr] 4d^4\) both have configurations that could satisfy this, and need further exploring for unpaired electron count.

Key Concepts

Electron Configuration

Understanding electron configuration is crucial for grasping how transition metals interact and form ions. The electron configuration of an atom indicates the distribution of electrons in an atom's orbitals. For transition metals like Yttrium (\(Y\)) through Cadmium (\(Cd\)), the electrons primarily occupy the 4d subshell. Each element has a specific electron configuration reflecting its total number of electrons. For example, Yttrium (\(Y\)) is represented as \([Kr] 4d^1 5s^2\). Transition elements typically exhibit partially filled d-sublevels which lead them to have varied chemical properties. When dealing with transition series, we analyze how these electrons configure around each element to predict their behavior in different chemical contexts, such as ionization.

Ionization Process

The ionization process involves removing electrons from an atom to form a positive ion. For transition metals, this typically means removing the electrons from their highest energy orbitals first. When forming a \(3^+\) ion, three electrons are removed. These usually come from the s and d orbitals, starting with the outermost electrons:

• Electrons from the 5s orbital are removed first.
• Then, d orbital electrons are removed if needed to reach the \(3^+\) charge.

For example, if you have an element with the configuration \([Kr] 4d^4 5s^1\), creating a \(3^+\) ion would result in removing the 5s electron and two more from the 4d sublevel. This process can lead to changes in magnetic properties and reactivity of the element due to electron configuration shifts.

Unpaired Electrons

Unpaired electrons significantly influence the chemical properties of an element. In transition metals, unpaired electrons can affect magnetism and bonding capabilities. To find elements with four unpaired electrons, we examine the provided configurations after ionization. Each unpaired electron contributes to the total magnetic moment of the ion.For elements like \(Mo^{3+}\) with \[ [Kr] 4d^3 \], unpaired electrons are present in the d orbitals. In the case of \(Tc^{3+}\), with \[ [Kr] 4d^4 \], further analysis will confirm the electron's spin states to determine the presence of unpaired electrons. Identifying unpaired electrons is essential for understanding transition metals' behavior in various chemical environments.

Second Transition Series

The second transition series spans Yttrium (\(Y\)) through Cadmium (\(Cd\)). These elements are distinguished by the filling of the 4d subshell. This subshell configuration plays a crucial role in defining the unique chemical and physical properties of the series.In examining the periodic table:

• Elements transition from filling 5s orbitals to increasingly filling the 4d orbitals.
• Each element features a distinct electron arrangement that affects its chemical reactivity.

The unique electron configuration leads these metals to display various states of oxidation. The study of the second transition series allows chemists to explain phenomena like color, magnetism, and complex formation in substances containing these metals. Understanding this helps identify elements like Mo and Tc, which have particular relevance in industrial and biochemical applications.