Difference Between Actinides and Lanthanides

Main Difference – Actinides vs Lanthanides

Actinides and lanthanides are chemical elements that are found in the f block of the periodic table of elements. This means their valence electrons are in the f orbital of their atoms. These chemical elements are found as metals and are called inner transition metals. The f block consists only of the lanthanide series and actinide series. These periods are given these names since the actinide series starts from a chemical called Actinium and the lanthanide series starts from a chemical element called Lanthanum. The chemical elements in the actinide series are called actinides, and the elements in the lanthanide series are called lanthanides. The main difference between actinides and lanthanides is that actinides can form complexes easily whereas lanthanides do not form complexes easily.

Key Areas Covered

1. What are Actinides
      – Definition, General Properties
2. What are Lanthanides
      – Definition, General Properties
3. What is the Difference Between Actinides and Lanthanides
      – Comparison of Key Differences

Key Terms: Actinides, Actinium, F Block Elements, Inner Transition Metals, Lanthanides, Lanthanum

What are Actinides

Actinides are chemical elements that can be found in the actinide series of the f block in the periodic table of elements. All actinides are radioactive elements due to their unstable nature. These elements are composed of very large atoms. Actinides have their valence electrons in the 5f orbital. The actinide series is composed of chemical elements having the atomic numbers 89 to 103.

Figure 1: Location of actinide series in the periodic table of elements.

The most common and abundant actinides on earth are Uranium and Thorium. They are weakly radioactive and release high energy during radioactive decay. The prominent oxidation state among actinides is +3. In addition, actinides show oxidation states such as +4, +5 and +6.

Actinides form basic oxides and hydroxides. They have the ability to form complexes with ligands such as chlorides, sulfates, etc. Most complexes of actinides are colorful. However, due to the radioactivity and heavy metal behavior, actinides are considered as toxic compounds.

What are Lanthanides

Lanthanides are chemical elements that can be found in the lanthanide series of the f block in the periodic table of elements. Lanthanides are non-radioactive except for Promethium. Since atomic numbers of lanthanides range from 57 to 71, they are also composed of comparatively large atoms. The valence electrons of lanthanides are in the 4f orbital.

Figure 2: Location of Lanthanides in the Periodic Table of Elements

Lanthanides are metallic elements. Therefore, they are oxidized in moist air. They also dissolve quickly in acids. Lanthanides can react with oxygen and halides, but slowly. The most prominent oxidation state of lanthanides is +3. Other oxidation states that lanthanides show are +2 and +4. But they cannot have +6 oxidation state. Therefore, they cannot form complex molecules. Lanthanides do not form oxocations such as oxides and hydroxides. The molecules formed by lanthanides are less basic.

Almost all the ions formed by lanthanides are colorless. Lanthanides are electropositive elements. Therefore, they prefer to form molecules with electronegative elements. However, throughout the series, the changes of the chemical and physical properties is very less.

Difference Between Actinides and Lanthanides

Definition

Actinides: Actinides are chemical elements that can be found in the actinide series of the f block in the periodic table of elements.

Lanthanides: Lanthanides are chemical elements that can be found in the lanthanide series of the f block in the periodic table of elements.

Atomic Numbers

Actinides: The atomic number of actinides ranges from 89 to 103.

Lanthanides: The atomic number of lanthanides ranges from 57 to 71.

Position in the Periodic Table

Actinides: Actinides are in the actinide series of the f block in the periodic table.

Lanthanides: Lanthanides are in the lanthanide series of the f block of the periodic table.

Radioactivity

Actinides: Actinides are radioactive elements.

Lanthanides: Lanthanides are non-radioactive elements (except Promethium).

Oxidation States

Actinides: Actinides can have a maximum of +6 oxidation state.

Lanthanides: Lanthanides can have a maximum of +4 oxidation state.

Valence Electrons

Actinides: The valence electrons of the actinides are in the 5f orbital.

Lanthanides: The valence electrons of the lanthanides are in the 4f orbital.

Summary

Actinides and lanthanides are chemical elements that can be found in the f block of the periodic table. Actinides are radioactive elements. Lanthanides are non-radioactive elements with some exceptions. The main difference between actinides and lanthanides is that actinides can form complexes easily whereas lanthanides do not form complexes easily.

References:

1. “Lanthanides: Properties and Reactions.” Chemistry LibreTexts, Libretexts, 20 Aug. 2017, Available here. Accessed 7 Sept. 2017.
2. “Lanthanides and Actinides – Boundless Open Textbook.” Boundless, Boundless, 19 Apr. 2017, Available here. Accessed 7 Sept. 2017.

Image Courtesy:

1. “Actinide-table” (CC BY-SA 3.0) via Commons Wikimedia
2. “Period table” By The original uploader was Kushboy at English Wikipedia – Transferred from en.wikipedia to Commons. (CC BY-SA 3.0) via Commons Wikimedia