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The rare-earth elements (REE), also called the rare-earth metals or rare earths, and sometimes the lanthanides or lanthanoids (although scandium and yttrium, which do not belong to this series, are usually included as rare earths), [1] are a set of 17 nearly indistinguishable lustrous silvery-white soft heavy metals. Compounds containing rare ...
Naturally occurring erbium is composed of 6 stable isotopes, 162 Er, 164 Er, 166 Er, 167 Er, 168 Er, and 170 Er, with 166 Er being the most abundant (33.503% natural abundance). 32 radioisotopes have been characterized, with the most stable being 169 Er with a half-life of 9.392 d, 172 Er with a half-life of 49.3 h, 160 Er with a half-life of ...
Has no known biological role, and is extremely rare in the Earth's crust. The isotope plutonium-238 is used as an energy source in some heart pacemakers. [11] Both toxic and radioactive. polonium: 84: 1b: Has no known biological role, and due to its short half-life, is nearly nonexistent outside of research facilities. [11] Both highly toxic ...
Like most other rare earth elements, its usual oxidation state is +3, although some compounds are known with an oxidation state of +2. Lanthanum has no biological role in humans but is used by some bacteria. It is not particularly toxic to humans but does show some antimicrobial activity. Lanthanum usually occurs together with cerium and the ...
The study shows that more than 16 million short tons (15 billion kilograms) of rare-earth elements could be "exploited in the near future." As well as yttrium (Y), which is used in products like camera lenses and mobile phone screens, the rare-earth elements found are europium (Eu), terbium (Tb), and dysprosium (Dy). [55]
Thirty-two radioisotopes have been observed, with the most stable ones being 169 Yb with a half-life of 32.0 days, 175 Yb with a half-life of 4.18 days, and 166 Yb with a half-life of 56.7 hours. All of the remaining radioactive isotopes have half-lives that are less than two hours, and most of these have half-lives under 20 minutes.
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Praseodymium is not particularly rare, despite it being in the rare-earth metals, making up 9.2 mg/kg of the Earth's crust. [43] Praseodymium's classification as a rare-earth metal comes from its rarity relative to "common earths" such as lime and magnesia, the few known minerals containing it for which extraction is commercially viable, as ...