The term "rare" most often refers to rare-earth elements.
Rare-Earth Elements: A Closer Look
Rare-earth elements (REEs) are a group of 17 chemical elements in the periodic table. They consist of scandium (Sc), yttrium (Y), and the lanthanides (elements with atomic numbers 57–71, from lanthanum [La] to lutetium [Lu]). Despite their name, most REEs are not particularly rare in the Earth's crust. However, they are rarely found in concentrated and economically exploitable deposits, hence the "rare" designation.
The Rare-Earth Element Group
Here's a breakdown of the elements included in the rare-earth element group:
- Scandium (Sc)
- Yttrium (Y)
- 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)
- Lutetium (Lu)
Why are They Important?
Rare-earth elements are crucial in many modern technologies. They are used in:
- Electronics: Smartphones, computers, and televisions
- Renewable Energy: Wind turbines and solar panels
- Defense: Missile guidance systems and military communication
- Medical Technology: MRI contrast agents
Misconceptions About Rarity
It is important to reiterate that the term "rare" refers more to the difficulty in finding economically viable concentrations rather than absolute scarcity in the Earth's crust. Some REEs are more abundant than common metals like copper or lead.
In conclusion, when someone asks "what element is rare?", the most likely answer is a rare-earth element. While not all are truly scarce, their dispersed nature and the challenges in extracting them justify the "rare" moniker.
