Lanthanide
15 metallic elements from lanthanum to lutetium, filling 4f orbitals.
Last updated
The lanthanides are a set of 15 metallic elements, spanning atomic numbers 57 through 71, from lanthanum to lutetium. In the periodic table, the first fourteen of these (up to ytterbium) fill the 4f orbitals. Lutetium, element 71, is a d-block element and a transition metal, but it is still generally counted as a lanthanide because its behavior closely matches the others.
Etymology
The International Union of Pure and Applied Chemistry (IUPAC) officially recommends the name "lanthanoid" for this series (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu), as the suffix "-oid" better indicates similarity to lanthanum, while "-ide" is usually reserved for negative ions. Despite this, "lanthanide" remains the common term. In discussions of lanthanide chemistry, the informal symbol Ln is used to refer to any element in the group. All but one of the lanthanides are f-block elements, corresponding to the filling of the 4f electron shell.
The term "rare-earth element" or "rare-earth metal" often includes the stable group 3 elements scandium, yttrium, and lutetium along with the 4f elements. Every lanthanide forms a trivalent cation, Ln³⁺, and their chemistry is largely governed by a steady decrease in ionic radius from lanthanum to lutetium. Several can also take on +2 or +4 oxidation states.
In periodic table layouts, the f-block elements are usually placed in two separate rows below the main table—a convention driven by aesthetics and formatting convenience. A wide-formatted table, though rarely used, inserts the 4f and 5f series into their proper positions in the sixth and seventh periods. The term "lanthanide" was introduced by Victor Goldschmidt in 1925. Despite their actual abundance, the name reflects a sense of elusiveness, coming from the Greek lanthanein, meaning "to lie hidden." This refers to how these elements "hide" behind each other in minerals.
The name derives from lanthanum, first discovered in 1838, which was itself a new rare-earth element "lying hidden" in a cerium mineral. Ironically, lanthanum later became the first in a whole series of chemically similar elements and gave its name to the group. Because "lanthanide" means "like lanthanum," some argue that lanthanum itself cannot logically be a lanthanide, but IUPAC includes it based on common usage.
Quick Facts
- Atomic numbers
- 57–71
- Elements
- La
- Ce
- Pr
- Nd
- Pm
- Sm
- Eu
- Gd
- Tb
- Dy
- Ho
- Er
- Tm
- Yb
- Lu
- Common oxidation state
- +3
- Term origin
- Greek λανθανειν (lanthanein), 'to lie hidden'
- Iupac recommended name
- lanthanoid
Facts from the source article.
Lore & Background
The IUPAC recommends the name 'lanthanoid' because the suffix '-ide' is preferred for negative ions, while '-oid' indicates similarity to a family member, but 'lanthanide' remains common. The lanthanides fill the 4f electron shell progressively from lanthanum to lutetium, with lutetium being a d-block element. Their chemistry is dominated by the +3 oxidation state, and all form trivalent cations Ln3+.
The ionic radius decreases steadily from lanthanum to lutetium (the lanthanide contraction), explained by poor shielding of 5s and 5p electrons by 4f electrons. Several lanthanides can also form +2 and +4 oxidation states, but only Ce(IV) and Eu(II) are stable in aqueous solution. In the periodic table, the f-block elements are customarily shown as two additional rows below the main body, a matter of aesthetics and formatting practicality.
A rarely used wide-formatted table inserts them in their proper places in the sixth and seventh rows. The lanthanides are soft metals; their hardness increases across the series. Europium has the lowest density and largest metallic radius, while gadolinium becomes ferromagnetic below 16 °C.
Reader's Guide
The lanthanides are significant for their unique electronic, magnetic, and optical properties arising from the progressive filling of the 4f orbitals. Their chemistry is largely determined by the +3 oxidation state and the lanthanide contraction, which affects ionic radii and bonding. They are highly reducing metals, with reduction potentials similar to alkaline earth metals.
The f→f transitions in lanthanides produce weak, narrow spectra, making their complexes fainter in color than transition metal complexes. Their magnetic moments can be as high as 7 unpaired electrons, leading to strong paramagnetism in most lanthanides. The term 'rare-earth element' often includes scandium, yttrium, and lutetium along with the 4f elements.
Despite their name, lanthanides are not rare in abundance. Their applications stem from subtle variations in electronic, electrical, optical, and magnetic properties, and purification requires repeated solvent and ion-exchange methods due to very small solubility differences. The inclusion of lutetium as a lanthanide has been questioned because it is a d-block element, but it behaves similarly to the other 14.
Frequently Asked Questions
Who is Lanthanide?
Lanthanide is the collective name for the 15 metallic elements with atomic numbers 57 through 71, stretching from lanthanum to lutetium. They predominantly fill the 4f electron subshell and share a dominant +3 oxidation state, though lutetium is technically a d-block transition metal that still behaves like the rest of the group.
What is Lanthanide known for?
As f-block elements, lanthanides contribute a wide toolkit of magnetic, optical, and catalytic properties driven by their partially filled 4f orbitals. Their nearly identical ionic radii and shared +3 charge make them notoriously hard to separate from one another, yet that same chemistry powers everything from permanent magnets to phosphor displays.
More in Chemistry & Materials
Sources
Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.
- Wikipedia: Lanthanide (CC BY-SA 4.0).
- Word definitions: the Codexery glossary, each quoted from its Wikipedia article.
Spotted an error? Know more?
Reader corrections go straight into our review queue. Suggest an edit · How this site is sourced