Question

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

Short answer

Molybdenum (Mo) and Technetium (Tc) fit this description.

Step-by-step solution

Understand the elements in the second transition series

The second transition series of elements includes the elements Yttrium (Y) through Cadmium (Cd) on the periodic table. These elements are characterized by their partially filled d-orbitals.

Determine the electronic configuration of 3+ ions

For each element (Y through Cd), determine the electron configuration of their 3+ ions. Removing three electrons typically starts from the outermost shell, usually involving the s and d orbitals.

Identify elements with four unpaired electrons

For each 3+ ion configuration, count the number of unpaired electrons in the d-orbitals. We are looking for configurations showing exactly four unpaired electrons.

List the suitable elements

From the configurations, identify those which, as a 3+ ion, align with having exactly four unpaired electrons in their d-orbitals. Specifically, look for the electronic configuration ending in d⁵, as it represents having four unpaired electrons.

Key concepts

Electron Configuration

Electron configuration is key to understanding the chemical behavior of transition metals. It's the distribution of electrons among the different orbitals of an atom. Transition metals have electrons filling their "d" orbitals, which is what makes them intriguing. These orbitals can hold up to 10 electrons. Often, electron removal or addition affects these d-orbitals.
When we form 3+ ions from transition metals, we must remove three electrons. To do this, we usually start with the outermost electrons, typically from the "s" as well as "d" orbitals. This results in a modified configuration of the ion compared to its neutral atom. Understanding these changes helps us predict the properties of these ions. It's essential to also consider factors like stability and energy when determining these configurations.

Unpaired Electrons

Unpaired electrons are electrons that reside alone in an orbital. This makes them important for understanding the magnetic properties of a material.
In transition metals, it's the unpaired electrons in the d-orbitals that play a significant role. Orbital pairing is when electrons occupy the same orbital but have opposite spins. Naturally, transition metals can have varying numbers of unpaired electrons. These unpaired electrons lead to unique characteristics, such as paramagnetism.

• Paramagnetism is when unpaired electrons align with external magnetic fields, causing attraction.
• More unpaired electrons lead to stronger magnetic properties.

Specifically, the requirement for a 3+ ion having four unpaired electrons involves achieving a d⁵ configuration. This situation arises when five electrons occupy the d-orbitals, leaving one less in each, thus all being unpaired.

Transition Series Elements

The second transition series consists of elements from Yttrium (Y) to Cadmium (Cd). These elements share the characteristic of having partially filled d-orbitals. Transition metals, including these series, are crucial in various industries due to their unique properties like malleability and conductivity.
The series also shows variability in oxidation states, meaning the ability of an element to lose electrons and form positive ions. This variability is due to the relatively low energy differences between the s and d-orbitals, allowing for different combinations of electron loss.

• Yttrium (Y) sits at the start of the series, known for a singular stable oxidation state.
• Cadmium (Cd), the last element, is less prone to forming 3+ ions, often forming Cd²⁺.

Studying this series of elements helps us understand how small changes in electron configurations can lead to various chemical behaviors and properties, heightening our knowledge of transition metal chemistry.