Lanthanide
15 metallic elements from lanthanum to lutetium, filling 4f orbitals.
Lanthanides are any of the 15 metallic chemical elements with atomic numbers 57–71, from lanthanum through lutetium. They are also known as lanthanoids, a term recommended by IUPAC as chemically more correct. All but one are f-block elements, filling the 4f orbitals; lutetium is a d-block element and a transition metal, but behaves similarly to the other 14. The informal chemical symbol Ln is used in general discussions of lanthanide chemistry.
- 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
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.
Did You Know?
- The term 'lanthanide' comes from Greek 'lanthanein', meaning 'to lie hidden', reflecting their elusiveness in minerals.
- Gadolinium becomes ferromagnetic at below 16 °C.
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 are Lanthanide's powers/role?
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.
How does Lanthanide's story end?
The 15-member series closes with lutetium (Z = 71), the sole d-block element in the set. Despite that technical distinction, lutetium's chemistry mirrors its 14 lanthanide companions, so it is universally counted as the final entry in the group.
Why is Lanthanide important?
Lanthanides are irreplaceable in modern technology: neodymium and samarium enable high-strength permanent magnets, europium and terbium provide the red and green phosphors in screens, and cerium serves as a key catalytic component in petroleum refining. No other element family reproduces this combination of 4f-driven properties.
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