Question

Match up the isoelectronic ions on the following list. $$\mathrm{Cu}^{+} \mathrm{Mn}^{2+} \mathrm{Fe}^{2+} \mathrm{Co}^{3+} \mathrm{Fe}^{3+} \mathrm{Zn}^{2+} \mathrm{Ti}^{2+} \mathrm{V}^{3+}$$

Short answer

Pairs: \(\mathrm{Cu}^{+}/\mathrm{Zn}^{2+}, \mathrm{Fe}^{2+}/\mathrm{Co}^{3+}, \mathrm{Mn}^{2+}/\mathrm{Fe}^{3+}, \mathrm{Ti}^{2+}/\mathrm{V}^{3+}\).

Step-by-step solution

Understanding Isoelectronic Species

Isoelectronic species are ions or atoms that have the same number of electrons. In this exercise, we need to find pairs of ions from the given list that are isoelectronic, meaning they have the same total number of electrons.

Calculating Electron Counts

Let's find the number of electrons in each ion. We use the atomic number from the periodic table and adjust for the ion's charge:- \(\mathrm{Cu}^{+}\): Copper has 29 electrons, loses 1: 28 electrons- \(\mathrm{Mn}^{2+}\): Manganese has 25 electrons, loses 2: 23 electrons- \(\mathrm{Fe}^{2+}\): Iron has 26 electrons, loses 2: 24 electrons- \(\mathrm{Co}^{3+}\): Cobalt has 27 electrons, loses 3: 24 electrons- \(\mathrm{Fe}^{3+}\): Iron has 26 electrons, loses 3: 23 electrons- \(\mathrm{Zn}^{2+}\): Zinc has 30 electrons, loses 2: 28 electrons- \(\mathrm{Ti}^{2+}\): Titanium has 22 electrons, loses 2: 20 electrons- \(\mathrm{V}^{3+}\): Vanadium has 23 electrons, loses 3: 20 electrons.

Finding Isoelectronic Pairs

Now, we match ions with the same number of electrons:- \(\mathrm{Cu}^{+}\) with \(\mathrm{Zn}^{2+}\) both have 28 electrons.- \(\mathrm{Fe}^{2+}\) with \(\mathrm{Co}^{3+}\) both have 24 electrons.- \(\mathrm{Mn}^{2+}\) with \(\mathrm{Fe}^{3+}\) both have 23 electrons.- \(\mathrm{Ti}^{2+}\) with \(\mathrm{V}^{3+}\) both have 20 electrons.

Key concepts

Electron Configuration

Electron configuration is a fundamental concept in chemistry that refers to the arrangement of electrons around the nucleus of an atom. Every element has a unique electron configuration, dictating its chemical properties and reactivity.
Understanding electron configurations helps us in predicting how atoms will interact with one another, form ions, or bond to create molecules. Here’s how it generally works:

• Electrons are arranged in shells or energy levels around the nucleus, denoted by numbers like 1, 2, 3, and so on.
• These shells contain subshells or orbitals labeled as s, p, d, and f.
• The arrangement is guided by the Aufbau principle, Hund's rule, and the Pauli-Exclusion principle.
• The s orbital can hold 2 electrons, p can hold 6, d can hold 10, and f can hold 14.

For transition metals, the electron configuration becomes particularly interesting because they involve filling the d subshell. When you form ions, electrons are typically removed from the outermost shell first. Knowing the electron configuration helps determine the ion's charge and chemical behavior.

Chemistry Problem Solving

Solving chemistry problems, especially with isoelectronic ions, involves systematic approaches to avoid errors. Let's delve into some strategies that can help make these problems easier to handle:

• **Identify the Goal**: Know exactly what you are trying to find. Are we matching ions, calculating electron numbers, or predicting chemical properties?
• **Basic Information**: Gather all necessary data from the periodic table, such as atomic numbers and typical ion charges.
• **Calculate**: Specifically for isoelectronic ions, calculate the number of electrons by adding or subtracting based on the ion's charge. For example, a \(Cu^{+}\) ion has one less electron than a neutral copper atom, giving it 28 electrons.
• **Compare and Contrast**: Write down electron counts for each ion, then match those with identical electron numbers. Use logical reasoning to verify your answers.

Chemistry problem solving is about consistent practice and applying these techniques to different kinds of problems to build understanding and accuracy.

Transition Metal Ions

Transition metal ions, found in the d-block of the periodic table, have unique properties due to partially filled d orbitals. Their electron configurations are crucial for understanding their chemical behaviors.
Here are some interesting facts about them:

• **Variable Oxidation States:** Transition metals can form ions with different charges (oxidation states). This feature is due to the capability to lose varying numbers of d electrons.
• **Colorful Compounds:** Because of their electron configurations, many transition metal compounds have vivid colors. This relates to d-d electron transitions and the specific energy levels involved.
• **Magnetic Properties:** Many transition metal ions show magnetic properties, as a result of unpaired d electrons.
• **Complex Formation:** These ions can form complex structures with other molecules, often acting as catalysts in chemical reactions.

These attributes make transition metals and their ions central to discussions in inorganic chemistry and explain their widespread industrial and biological importance. When dealing with problems involving transition metals, understanding their electron configuration, and potential oxidation states, is key.