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Neodymium is not found naturally in metallic form or unmixed with other lanthanides, and it is usually refined for general use. Neodymium is fairly common—about as common as cobalt, nickel, or copper—and is widely distributed in the Earth's crust. [10] Most of the world's commercial neodymium is mined in China, as is the case with many ...
In 1934, Willard Libby reported that he had found weak beta activity in pure neodymium, which was attributed to a half-life over 10 12 years. [25] Almost 20 years later, it was claimed that the element occurs in natural neodymium in equilibrium in quantities below 10 −20 grams of promethium per one gram of neodymium. [ 25 ]
Parts-per-million cube of relative abundance by mass of elements in an average adult human body down to 1 ppm. About 99% of the mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Only about 0.85% is composed of another five elements: potassium, sulfur, sodium, chlorine, and magnesium ...
Perey discovered it as a decay product of 227 Ac. [184] Francium was the last element to be discovered in nature, rather than synthesized in the lab, although four of the "synthetic" elements that were discovered later (plutonium, neptunium, astatine, and promethium) were eventually found in trace amounts in nature as well. [185]
[37]: 104 It can be made by the reaction of gallium with hydrogen sulfide (H 2 S) at 950 °C. [33]: 162 Alternatively, Ga(OH) 3 can be used at 747 °C: [38] 2 Ga(OH) 3 + 3 H 2 S → Ga 2 S 3 + 6 H 2 O. Reacting a mixture of alkali metal carbonates and Ga 2 O 3 with H 2 S leads to the formation of thiogallates containing the [Ga 2 S 4] 2− anion.
This may be reduced to praseodymium(III) oxide (Pr 2 O 3) with hydrogen gas. [18] Praseodymium(IV) oxide , PrO 2 , is the most oxidised product of the combustion of praseodymium and can be obtained by either reaction of praseodymium metal with pure oxygen at 400 °C and 282 bar [ 18 ] or by disproportionation of Pr 6 O 11 in boiling acetic acid.
There is normally as little as 0.5 milligrams found within the entire human body; human breast milk contains 4 ppm. [82] Yttrium can be found in edible plants in concentrations between 20 ppm and 100 ppm (fresh weight), with cabbage having the largest amount. [82] With up to 700 ppm, the seeds of woody plants have the highest known concentrations.
1986: Karl Müller and Johannes Bednorz: Discovery of High-temperature superconductivity; 1988: Bart van Wees and colleagues at TU Delft and Philips Research discovered the quantized conductance in a two-dimensional electron gas. 1990: Mary-Claire King discovers the link between heritable breast cancers and a gene found on chromosome 17q21 ...