[summarize]
Rare earth is element of department of the lanthanum in chemical periodic chart, lanthanum (La) , cerium (Ce) , praseodymium (Pr) , neodymium (Nd) , Promethium (Pm) , scythe (Sm) , europium (Eu) , gadolinium (Gd) , Terbium (Tb) , dysprosium (Dy) , , and two elements closely related 15 elements that tie with lanthanum, scandium (Sc) He Yi (Y) in all 17 kinds of elements, call rare-earth element (Rare Earth) . Abbreviation rare earth (RE or R) .
[the classification of rare earth]
1) small rare land (weigh cerium batch again) : Lanthanum, cerium, praseodymium, neodymium, Promethium, scythe, europium, gadolinium.
2) heavy rare native (weigh yttric batch again) : Terbium, dysprosium, holmium, Erbium, Thulium, ytterbium, lutetium, Scandium, yttric.
Of cerium group and yttric group not, because mineral classics is detached,be in gotten rare earth compound, constant with cerium or yttric scale much and get a name.
Rare-earth metal (Rare Earth Metals) weighs rare-earth element again, it is periodic chart Ⅲ the floorboard that the Scandium in B a group of things with common features, yttric, lanthanum is 17 kinds of elements, commonly used R or RE express. Their name and chemical symbol are scandium (Sc) , yttrium (Y) , lanthanum (La) , cerium (Ce) , praseodymium (Pr) , neodymium (Nd) , Promethium (Pm) , scythe (Sm) , europium (Eu) , gadolinium (Gd) , Terbium (Tb) , dysprosium (. Their atomic number is 21(Sc) , 39(Y) , 57(La) to 71(Lu) .
[name origin]
Rare earth one word is the name that the history leaves. Rare-earth element is from 18 centuries last years begins to discover in succession, at that time people constant not dissolve calls land at the solid oxide of water. Rare earth comes out with oxide condition depart commonly, very exiguous, get a name to be rare earth consequently. Call lanthanum, cerium, praseodymium, neodymium, Promethium, scythe, europium normally rare earth of small rare land or cerium group; Weigh yttrium of gadolinium, Terbium, dysprosium, holmium, Erbium, Thulium, ytterbium, lutetium to attach most importance to rare earth of rare earth or yttric group. Also some according to rare-earth element the similar sex of physico-chemical property is mixed otherness, except scandium (put under of some general Scandium is rare medicinal powder elemental) , differentiate 3 groups, namely group of small rare land is lanthanum, cerium, praseodymium, neodymium, Promethium; Rare land group is samarium, europium, gadolinium, Terbium, dysprosium in; Group of heavy rare native is holmium, Erbium, Thulium, ytterbium, lutetium, yttrium.
The discovery of these rare-earth element, from Finnic 1794 Jiaduolin (J.Gadolin) depart gives yttrium to arrive 1947 American Malinsiji (J.A.Marinsky) make promethium, last a period of time 150 old. Among them the discovery such as a few mineralogical home, chemist that major rare-earth element is Europe, metallurgy home is made take. Promethium is American Malinsiji, Gelandening (L.E.Glendenin) and Kelieer (C.D.Coryell) departs with ion exchange, obtain in the rare-earth element of uranous fission product. Thought nature is medium in the past nonexistent Promethium, till 1965, when handling apatite, factory of a phosphate discovered Finland the Promethium of trace.
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