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How are lanthanides different from rare-earth elements?
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rare-earth element
Electron probabilities, P2(r), for the 4f, 5s, 5p, 5d, and 6s electrons of gadolinium.
The terms "lanthanides" and "rare-earth elements" are often confused, but they refer to distinct, though overlapping, groups of chemical elements.
A rare-earth element is defined as a group of 17 elements that includes scandium, yttrium, and the 15 lanthanide elements (lanthanum through lutetium).12
The primary differences are:
- Composition: The lanthanide series consists specifically of the 15 consecutive elements with atomic numbers 57 through 71. Rare-earth elements encompass this entire series plus scandium (atomic number 21) and yttrium (atomic number 39).12
- Classification: Lanthanides are a specific chemical series within the periodic table. Rare-earth elements are a broader classification that groups these metals together based on their shared occurrence in nature and similar chemical properties.12
Despite the name, rare-earth elements are not actually rare; they are relatively abundant in the Earth's crust. The term "rare earth" originated in the 18th century because they were initially discovered in complex oxides—then called "earths"—that appeared to be scarce.2