Question

Which elements have a partially filled \(d\) sublevel?

Short answer

The elements with partially filled \(d\) sublevels are the transition metals found in the \(d\) block of the Periodic Table, specifically groups 3 to 12. These include 40 elements, with Chromium and Copper as notable exceptions due to their unique electron configurations.

Step-by-step solution

Identify the \(d\) block on the Periodic Table

The Periodic Table has four blocks: \(s\), \(p\), \(d\), and \(f\). The \(d\) block corresponds to the transition metals, located in the center of the Periodic Table. This block comprises groups 3 to 12.

Recognize the elements with partially filled \(d\) sublevels

Each of the transition metals, at some point during their formation, have partially filled \(d\) orbitals. These elements include Scandium (Sc) through Zinc (Zn), Yttrium (Y) through Cadmium (Cd), and so forth. The full list includes 40 elements.

Understand the anomalies

Chromium (Cr) and Copper (Cu) are exceptions. Although they belong to the \(d\) block, they do not follow the general pattern. Chromium has a configuration of [Ar] 4s1 3d5, preferring half-filled energy levels to following the typical order. Copper also prioritizes stability and has a configuration of [Ar] 4s1 3d10. Even though they deviate, Cr and Cu are still elements with partially filled \(d\) levels at some point during their electron filling process.

Key concepts

Transition Metals

Transition metals are a group of elements that serve as the backbone of many important chemical processes. They are located in the center of the Periodic Table, spanning groups 3 to 12, and are commonly referred to as the 'd block'. These metals are unique due to their ability to exhibit a variety of oxidation states in chemical reactions. This interesting trait arises because of their partially filled

• d orbitals
• is a distinct property of transition metals.

As you might have predicted, this diversity allows transition metals to form complex compounds and contributes to their pivotal role in catalysis, metallurgy, and biological systems. Examples of well-known transition metals include Iron (Fe), Nickel (Ni), and Copper (Cu). Each of these elements have a partially filled d sublevel, making them versatile in bonding and electron configurations.

Electron Configuration

Understanding the electron configuration of an atom is essential in grasping how it behaves chemically. Electrons fill available orbital spaces around an atomic nucleus in a defined order, known as the Aufbau principle. Typically, the order is: 1s, 2s, 2p, 3s, 3p, 4s, and then 3d.

Transition metals, being part of the d block, begin filling the d sublevel after filling the 4s orbital. This is where electron configuration gets interesting. For example, Scandium (Sc) begins with 4s and then adds to 3d, with its configuration written as [Ar] 4s² 3d¹. Similarly, Iron (Fe) has the configuration [Ar] 4s² 3d⁶, indicating that it's part of the transition metals class with electrons in the d sublevel.

The significant concept to remember is that transition metals always retain partially filled d orbitals at some stage during electron filling, which is a trait not generally seen in the s or p block elements.

Anomalies in Electron Filling

The process of completing electron shells doesn’t always follow the anticipated pattern. Some elements, particularly transition metals like Chromium (Cr) and Copper (Cu), showcase unusual electron filling due to their desire for stability.

For example, Chromium is expected to have the configuration [Ar] 4s² 3d⁴, but instead, it rearranges to [Ar] 4s¹ 3d⁵. This change occurs because a half-filled d subshell offers more stability due to decreased electron repulsion.

Similarly, Copper should theoretically feature [Ar] 4s² 3d⁹, but the more stable [Ar] 4s¹ 3d¹⁰ is observed. This full d sublevel configuration offers an additional layer of stability, even if it means "borrowing" an electron from the 4s orbital. These anomalies teach us that electron configuration is not just about following a sequence; it's a dance towards achieving the most energetically favorable setup. Consequently, even these anomalies in transition metals lead to partially filled d sublevels at various times.