Lanthanoids - Class 12 Chemistry
Introduction
Lanthanoids (or lanthanides) are a group of 15 elements in the periodic table, ranging from
lanthanum (La, Z = 57) to lutetium (Lu, Z = 71). These elements belong to the f-block of
the periodic table and are also known as rare earth metals.
Electronic Configuration
The general electronic configuration of lanthanoids is:
[Xe] 4f(1-14) 5d(0-1) 6s(2)
- Lanthanum (La) has no electrons in the 4f orbital, but from cerium (Ce) onwards,
the 4f orbitals start filling.
- The filling of the 4f subshell results in similar chemical properties across the series.
Oxidation States
- The most common oxidation state of lanthanoids is +3.
- Some elements (like Ce, Pr, Tb, and Dy) can also exhibit +2 and +4 oxidation states.
Properties of Lanthanoids
1. Physical Properties
- Metallic nature: Soft, silvery-white metals.
- High melting and boiling points: However, they do not follow a regular trend.
- Density: Increases across the series.
- Atomic and ionic size: Decreases across the series due to lanthanide contraction.
2. Chemical Properties
Introduction
Lanthanoids (or lanthanides) are a group of 15 elements in the periodic table, ranging from
lanthanum (La, Z = 57) to lutetium (Lu, Z = 71). These elements belong to the f-block of
the periodic table and are also known as rare earth metals.
Electronic Configuration
The general electronic configuration of lanthanoids is:
[Xe] 4f(1-14) 5d(0-1) 6s(2)
- Lanthanum (La) has no electrons in the 4f orbital, but from cerium (Ce) onwards,
the 4f orbitals start filling.
- The filling of the 4f subshell results in similar chemical properties across the series.
Oxidation States
- The most common oxidation state of lanthanoids is +3.
- Some elements (like Ce, Pr, Tb, and Dy) can also exhibit +2 and +4 oxidation states.
Properties of Lanthanoids
1. Physical Properties
- Metallic nature: Soft, silvery-white metals.
- High melting and boiling points: However, they do not follow a regular trend.
- Density: Increases across the series.
- Atomic and ionic size: Decreases across the series due to lanthanide contraction.
2. Chemical Properties
