The lanthanide group, also known as the lanthanides or rare earth elements,

The lanthanide group, also known as the lanthanides or rare earth elements, comprises 15 elements from lanthanum (La) to lutetium (Lu) with atomic numbers 57-71, characterized by their similar chemical and physical properties. 

Here's a more detailed breakdown:

Elements:

The lanthanide series consists of the following elements: Lanthanum (La), Cerium (Ce), Praseodymium (Pr), Neodymium (Nd), Promethium (Pm), Samarium (Sm), Europium (Eu), Gadolinium (Gd), Terbium (Tb), Dysprosium (Dy), Holmium (Ho), Erbium (Er), Thulium (Tm), Ytterbium (Yb), and Lutetium (Lu). 

Location in the Periodic Table:

These elements are placed in the f-block of the periodic table, specifically in the 4f orbitals, and are often placed below the main body of the periodic table for visual clarity. 

Similar Properties:

Lanthanides share similar chemical and physical properties due to their similar electron configurations, particularly in the filling of the 4f orbitals. 

Rare Earth Elements:

While often called "rare earth elements," the term is somewhat of a misnomer, as some lanthanides (like yttrium, cerium, lanthanum, and neodymium) are more abundant in the Earth's crust than some commonly used industrial elements. 

Uses:

Lanthanides have various applications, including in magnets, lasers, fluorescent lamps, catalytic converters, and medical imaging. 

Lutetium:

Lutetium (Lu), with atomic number 71, is sometimes considered a lanthanide, despite being a d-block element, because of its similar chemical behavior to the other 14 elements in the series. 

Lanthanide Contraction:

As you move across the lanthanide series, there is a decrease in atomic and ionic radii, known as the lanthanide contraction. 

Other Names:

The lanthanides are also sometimes referred to as the "lanthanoid elements"