The properties of rare earth elements depend on the electronic structure of rare earth atoms and rare earth ions. The properties of rare earth elements are closely related to the existence and distribution of rare earth elements in nature, the separation method of rare earth elements and the wide application of rare earth elements in various aspects. In order to better understand the separation and application of rare earth elements, it is necessary to study the physical and chemical properties of rare earth elements (metals and 3-valent ions). Rare earth elements are typical metals, usually silver gray, with a metallic sheen between iron and silver. Some metals that can form nonferrous salts are yellowish (such as praseodymium, neodymium, etc.). Rare earth metals are soft, such as cerium and lanthanum, but tend to harden as their atomic Numbers increase. Rare earth metals have good plasticity, among which cerium, samarium and ytterbium have good plasticity. For example, cerium can be rolled into thin sheets and pulled into filaments. Most rare earth metals have nearly hexagonal or face - centered cubic lattice structure, only samarium has a diamond structure, europium has body - centered cubic structure. The density of rare earth metals (except europium and ytterbium) and the melting point of rare earth metals (except lanthanum, europium and ytterbium) increase with the increase of atomic number. In density, scandium is the smallest, yttrium is next, thulium and lutetium are the largest, which is consistent with the trend of their atomic radius. They have the lowest boiling points in ytterbium and the highest in lanthanum and cerium.

The production method of cerium oxide is mainly oxalic acid precipitation method, that is, with cerium chloride or cerium nitrate solution as raw material, oxalic acid to adjust the pH value of 2, add ammonia precipitation cerium oxalate, heating, aging, separation, washing, drying at 110℃, and burning to cerium oxide at 900-1000℃. The salt of cerium oxide rare-earth element can reduce the content of prothrombin, deactivate it, inhibit the production of prothrombin, precipitate fibrinogen and catalyze the decomposition of phosphate compounds. The toxicity of rare-earth element is weakened with the increase of atomic weight. Inhalation of cerium dust, occupational pneumoconiosis, chloride damage to the skin, can irritate the eye mucosa. Maximum allowable concentration: 5 mg/m3 ceria, 5 mg/m3 ceria hydroxide, work should wear a respirator, if there is radioactivity to carry out special protection, to prevent the dust should be scattered.