Rare earth is the general name of lanthanide series, scandium, yttrium and other 17 metal elements in the chemical periodic table. Finnish chemist Gadolin separated the first rare earth "element" from a heavy ore shaped like asphalt in 1794.
Because few rare earth minerals were found in the18th century, only a small amount of water-insoluble oxides could be obtained by chemical methods. Historically, this oxide was customarily called "soil", hence the name rare earth.
Lanthanides in the Periodic Table of Chemical Elements —— La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, etc. RaRE earth (re or r) for short.
It is an important raw material for manufacturing high-tech weapons such as airplanes and missiles. The word rare earth is a name left over from history. Rare earth elements were discovered at the end of 18. At that time, people often called water-insoluble solid oxides soil. Soil is generally precipitated in oxide state, which is relatively rare, so it is named rare earth. Lanthanum, cerium, praseodymium, neodymium, promethium, samarium and europium are usually called light rare earth or cerium group rare earth; Gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium yttrium are called heavy rare earths or yttrium rare earths. According to the similarity and difference of physical and chemical properties of rare earth elements, some of them are divided into three groups (some are classified as sparse elements), that is, the light rare earth groups are lanthanum, cerium, praseodymium, neodymium and promethium; The medium rare earth group is samarium, europium, gadolinium, terbium and dysprosium; The heavy rare earth groups are holmium, erbium, thulium, ytterbium, lutetium and yttrium.