Question

What are rare earth elements?

Answer 1

1. Although, historically, lanthanoids are termed as rare earth elements, they are fairly abundant in earth’s crust.
   e.g. Thulium is found more in abundance than silver (4.5 × 10^–5 vs 0.79 × 10–5 percent by mass).
2. The names rare earth elements was coined because of difficulty in extracting them economically in pure form from other lanthanoids having similar chemical properties. Now, due to newer separation methods like ion exchange resins, the separation of these elements has become easier and more economical.