Question

Which energy sublevel is being filled by the actinide series?

Short answer

The actinide series fills the 5f sublevel.

Step-by-step solution

Understand the Context of the Actinide Series

The actinide series is a group of 15 chemical elements with atomic numbers from 89 (actinium) to 103 (lawrencium). These elements are found in the 7th period and the f-block of the periodic table, which is characterized by the filling of f-orbitals.

Identify the Sublevel Being Filled

The f-block is divided into two series: the lanthanides and the actinides. The lanthanides correspond to the filling of the 4f sublevel, and the actinides correspond to the filling of the 5f sublevel.

Conclusion on the Actinide Sublevel

Since the actinides are positioned in the 7th period of the periodic table within the f-block, the 5f sublevel is being filled as each successive element in the actinide series gains one more proton and one more electron than the previous element.

Key concepts

f-block elements

The f-block elements, often referred to as the inner transition metals, comprise two series of elements: the lanthanides and the actinides. These elements are unique because they involve the filling of f orbitals, which are located in the f-block of the periodic table.
One of the key characteristics of f-block elements is their complex electron configuration. The involvement of f orbitals means these elements feature partially filled f subshells.

• The lanthanides fill the 4f subshell.
• The actinides fill the 5f subshell.

Their position in the periodic table is separate, which helps keep the table more organized, as including these would require a significantly larger table. This layout aids in highlighting the similarities and differences among these elements and other main group elements. As transition metals, they exhibit multiple oxidation states and form colored ions in solutions.

5f sublevel

The 5f sublevel pertains specifically to the actinide series. This sublevel is the set of orbitals being filled by electrons as you progress through the elements in the actinide series.
Actinides are characterized by their use of the 5f subshell, beginning with protactinium (Pa), atomic number 91, and continuing through to lawrencium (Lr), atomic number 103.
The filling of the 5f sublevel is complex due to the high energy levels of these orbitals.
Unlike the more familiar s and p orbitals, f orbitals hold more electrons and have intricate shapes. Specifically, the 5f orbitals can hold up to 14 electrons, forming distinct chemical bonding patterns and reactivity levels as you move across the actinide series.
These properties make the 5f sublevel significant in understanding the behavior and chemistry of actinide elements, affecting their application in fields such as nuclear energy.

periodic table groups

The periodic table groups are columns of elements known for sharing similar properties due to their similar valence electron configurations. However, the f-block elements like lanthanides and actinides do not fit neatly into these traditional groupings.
Instead, they appear in two separated blocks at the bottom of the periodic table, emphasizing their differences in electron filling from other columns.
The grouping in the periodic table reflects electron configuration patterns rather than traditional groupings based on reactivity or other chemical properties.

• The actinide series fills the 5f sublevel, which does not align with standard columns.
• The elements display a range of oxidation states, which can differ from the norms seen in s or p block elements.

Understanding these discrepancies is crucial for grasping the chemical uniqueness and behavior of f-block elements in scientific and industrial contexts.