Difference Between Lanthanides and Actinides

The main difference between lanthanides and actinides is that lanthanides are the chemical elements in the f-block of the periodic table that do not form complexes easily while actinides are the chemical elements in the f-block of the periodic table that can form the complexes easily. …

lanthanides vs. actinides

f block elements are elements in which the last electron enters the f orbital of their atoms. These elements are also characterized as internal transition elements. They consist of two series that include the lanthanides and the actinides. The lanthanide series is the chemical element series that consists of 15 metallic chemical elements containing atomic numbers from 57 to 71, from lanthanum to lutetium. The actinide series, on the other hand, is the chemical element series that is made up of 15 metallic chemical elements containing atomic numbers from 89 to 103, from actinium to lawrencium.

The lanthanides are considered nonradioactive elements except for promethium. All actinides, on the other hand, are considered radioactive elements due to their unstable nature.

Comparison chart

Lanthanides are those chemical elements of the f block of the periodic table that do not form complexes easily. The atomic number of lanthanides ranges from 57 to 71. As they are metallic elements, they oxidize in moist air. They are also capable of rapidly dissolving in acids. Lanthanides can react with oxygen and halides, but this reaction occurs slowly. They are not capable of showing an oxidation state of +6. That is why they cannot form complex molecules. Lanthanides are considered electropositive elements. Therefore, they offer priority for making molecules with the electronegative elements. But the changes in physical and chemical properties are very minor throughout the series.

What are actinides ?

Actinides are those chemical elements of the f block of the periodic table that can easily form complexes. The atomic number of actinides ranges from 89 to 103. The most common and abundant actinides found on earth are thorium and uranium. They release high energy during radioactive decay. The prominent oxidation state shown by actinides is +3. The actinides produce basic hydroxides and oxides. They are capable of forming complexes with ligands such as sulfates, chlorides, etc. Most of the complexes formed by actinides are colourful. But actinides are considered toxic compounds due to their heavy metal behavior and radioactivity.

Key differences

1. Chemical elements that are present in the f-block lanthanide series in the periodic table are called lanthanides, while chemical elements that are present in the f-block actinide series in the periodic table are called actinides.
2. The atomic number of the elements present in the lanthanide series varies from 57 to 71; on the other hand, the atomic number of the elements present in the actinide series ranges from 89 to 103.
3. In the periodic table, lanthanides are found in the f-block lanthanide series. In contrast, in the periodic table, actinides are found in the f-block actinide series.
4. The oxidation states displayed by lanthanides are +2, +3, and +4, on the other hand, the oxidation states displayed by actinides are +3, +4, +5, and +6.
5. The maximum oxidation state displayed by the lanthanides is +4; on the other hand, the maximum oxidation state displayed by actinides is +6.
6. The lanthanides are considered to be non-radioactive elements, except for promethium, while all the actinides are considered to be radioactive elements due to their unstable nature.
7. The lanthanides do not participate in the formation of oxocations like oxides and hydroxides; on the other hand, actinides are involved in the formation of oxocations such as oxides and hydroxides.
8. The lanthanides show less basic behavior, while the actinides show more basic behavior.
9. Lanthanides exhibit less tendency to complex formation, on the other hand, actinides exhibit stronger tendency to complex formation.
10. Almost all of the ions that make up the lanthanides are colorless; on the other hand, most actinide complexes are colorful.
11. Lanthanides are not toxic compounds. In contrast, actinides are considered toxic compounds due to their heavy metal behavior and radioactivity.
12. The valence electrons of lanthanides are in the 4f orbital, on the other hand, the valence electrons of actinides are in the 5f orbital.

The above discussion summarizes that the lanthanides are considered non-radioactive elements and have some exceptions, while the actinides are the radioactive elements. The former could not easily complex, while the latter could easily complex.