Question

Which energy sublevel is being filled by the lanthanide series?

Short answer

The lanthanides fill the 4f energy sublevel.

Step-by-step solution

Understanding the Lanthanide Series

The lanthanide series consists of 15 elements with atomic numbers 57 through 71, from lanthanum (La) to lutetium (Lu). These elements are located in the f-block of the periodic table. Determining the energy sublevel being filled requires knowledge of electron configurations.

Identifying the f-block

Within the periodic table, the f-block is comprised of two series: the lanthanides and the actinides. The electron configuration for the f-block elements primarily involves the f sublevel, which follows the main d, s, and p block elements in energy.

Electron Configuration Basics

The lanthanides add electrons to the 4f subshell after the 6s sublevel. The typical electron configuration for lanthanides starts with the partially filled 4f sublevel, following xenon's configuration. This means that as you progress through the lanthanide series, electrons incrementally fill the 4f sublevel.

Conclusion

Since the lanthanides are located in the first row of the f-block and fill as we move through elements 57 to 71, we conclude that the 4f sublevel is the one being filled in this series.

Key concepts

Electron Configuration

Electron configuration is a method used to denote the arrangement of electrons in atomic orbitals around the nucleus of an atom. Based on this configuration, we can understand how electrons fill the available energy levels and sublevels in a structured way. The order of filling is generally determined by the Aufbau principle, which suggests that electrons fill orbitals starting from the lowest energy level to the highest.
- For example, in the case of the lanthanide series, electrons are added to the 4f sublevel after the 6s sublevel has been filled.
- Electrons tend to fill from lower energy sublevels such as 1s, 2s, 2p, and then move increasingly to higher energy sublevels like 3s, 3p, 4s, 3d, etc.
This methodical filling of electrons explains the chemical properties and reactivity of the elements. Understanding electron configuration is key to knowing how elements like those in the lanthanide series behave chemically.

F-Block Periodic Table

The periodic table is divided into different blocks, each representing a specific set of electron orbitals. Among these, the f-block is particularly intriguing. It contains elements where electrons are being added to the f orbital, characterized by their unique electron configurations and distinct properties.
- The f-block is divided into two series: the lanthanides and the actinides.
- Located below the main body of the periodic table, the f-block is not as prominently displayed, which sometimes can make it less familiar.
The f-block elements play a significant role in various applications, especially in technology and rare earth metals. The lanthanides, for example, are widely used in producing strong magnets and in various electronics. Recognizing where the f-block fits on the periodic table helps to visualize the arrangement of elements and their properties.

4f Sublevel

The 4f sublevel is an energy sublevel filled by electrons in the elements commonly known as the lanthanides. Each element in this series gradually fills the 4f orbital, distinguishing them from other elements in the periodic table.
- The 4f sublevel follows the 6s sublevel as you progress through the atomic number from 57 (Lanthanum) to 71 (Lutetium).
- A full 4f subshell holds 14 electrons, which is why there are exactly 15 lanthanides, including Lanthanum as the starter point for filling.
Understanding the 4f sublevel is crucial as it helps explain the properties of lanthanides. These elements are known for their complex electron setups and behaviors, showcasing unique magnetic and electronic characteristics. Recognizing how the 4f sublevel functions allows scientists and students alike to appreciate the intricacies involved in these fascinating elements.