Science chemistry question on "rare elements"?
A. There are no known uses for these elements.
B. unlike "common" elements, "rare elements are difficult to mine and process.
C. Most "rare elements were discovered only after 1900
D. They have unfamiliar or unusual names.
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B. unlike "common" elements, "rare elements are difficult to mine and process.
MORE INFORMATION ABOUT "RARE" ELEMENTS
Rare earth elements and rare earth metals are a collection of sixteen chemical elements in the periodic table, namely scandium, yttrium, and fourteen of the fifteen lanthanides (excluding promethium), which naturally occur on the Earth.
"Rare" was used because some of these elements were believed to be scarce in abundance as minerals. However, the term "rare earth" is now deprecated by IUPAC, as these elements are (except highly-unstable promethium),
in fact relatively abundant in the Earth's crust;
the most abundant, cerium, at 68 parts per million, is the 25th most abundant element in the crust, more common than lead, while even the least abundant "rare" earth element, lutetium, is 200 times more abundant than gold.
The principal economic sources of rare earth elements are the minerals bastnasite, monazite, and loparite and the lateritic ion-adsorption clays.
Despite their relative abundance, however, these are more difficult to mine and extract than the sources of transition metals (due in part to their very similar chemical properties), making them relatively expensive.
The following abbreviations are often used:
REE = rare earth elements
LREE = light rare earth elements (La-Sm)
HREE = heavy rare earth elements (Eu-Lu)
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