Brief Report

The lanthanide series of chemical elements consists of 15 metallic chemical elements with atomic numbers 57–71, beginning with lanthanum and ending with lutetium. These elements, as well as the chemically related elements scandium and yttrium, are commonly referred to as rare-earth elements or rare-earth metals. Lanthanides are so named because the elements in the class are chemically related to lanthanum. Lanthanum cannot theoretically be a lanthanide because "lanthanide" means "like lanthanum," yet the International Union of Pure and Applied Chemistry (IUPAC) recognises its inclusion based on common usage. Victor Goldschmidt coined the term "lanthanide" in 1925. Despite their abundance, the technical term "lanthanides" is interpreted to indicate these elements' elusiveness, as it originates from the Greek word (lanthanein), which means "to lie concealed." Instead of alluding to their natural abundance, the term refers to their ability to "hide" behind each other in minerals.

Lanthanum was discovered in 1838 as a so-called new rare- earth element "lying concealed" or "escaping notice" in a cerium mineral, and it is ironic that lanthanum was later identified as the first of an entire series of chemically identical elements and gave its name to thorium. The term "rare earths" is sometimes used to describe all lanthanides, along with the two elements at the top of group 3, scandium and yttrium; a definition of rare earths that includes the group 3, lanthanide, and actinide elements is also occasionally seen, and rarely Sc + Y + lanthanides + thorium. The "earth" in the name "rare earths" comes from the minerals used to isolate them, which were uncommon oxide-type minerals.

The 4f orbitals are frequently filled as one move over the periodic table of lanthanides. The 4f orbitals have a significant impact on the chemistry of lanthanides, and this is what distinguishes them from transition metals. There are seven 4f orbitals, and they are represented in two ways: as a "cubic set" or as a generic set. Because of the similarity in ionic radius between nearby lanthanide elements, it is difficult to separate them in naturally occurring ores and other combinations. Historically, the extremely time-consuming procedures of cascade and fractional crystallisation were employed. Because lanthanide ions have slightly different radii, the lattice energy of their salts and the hydration energies of the ions will differ slightly, resulting in a tiny difference in solubility.

Lanthanides exist mostly in their +3 oxidation state when in the form of coordination complexes, though especially stable 4f configurations can also provide +4 (Ce, Tb) or +2 (Eu, Yb) ions. Lanthanide ions are hard Lewis acids because all of these forms are strongly electropositive. Lanthanides are not employed for redox chemistry, with the exception of SmI2 and cerium (IV) salts, because their oxidation states are likewise very stable. Because of the low probability of 4f electrons residing at the atom's or ions outer region, there is little effective overlap between the orbitals of a lanthanide ion and any binding ligand. Thus, lanthanide compounds often lack covalent character and are unaffected by orbital geometries. Because of the lack of orbital interaction, changing the metal has little influence on the complex (other than size), especially when compared to transition metals. Complexes are kept together by weaker electrostatic interactions that are omnidirectional, and hence the symmetry and coordination of complexes are dictated solely by the ligands.

There is currently research indicating that lanthanide elements can be employed as anticancer drugs. Lanthanides' principal role in these investigations is to suppress cancer cell proliferation. Cerium and lanthanum, in particular, have been researched for their anti-cancer properties. Cerium is a particular element from the lanthanide group that has been tested and used (Ce). There have been researches that have used a protein-cerium combination to study the effect of cerium on cancer cells. The goal was to reduce cell growth and increase cytotoxicity. Transferrin receptors in cancer cells, such as those found in breast cancer and epithelial cervical cells enhance cell proliferation and cancer malignancy.