Scandium is a chemical element with the symbol Sc and atomic number 21. It is a soft, silver white transition metal with a melting point of 1541 ℃ and a boiling point of 2831 ℃. It is easily soluble in water, can react with hot water, and easily darkens in the air, with the main valence of+3. It is often mixed with gadolinium, erbium, etc., with little production, and the content in the crust is about 0.0005%. Scandium is often used to make special glass and light heat-resistant alloy.
Scandium is slightly yellowish or pink when oxidized by air, easily weathered and slowly dissolved in most dilute acids. However, an impermeable passivation layer is easily formed on the surface in strong acid, so it does not react with the 1:1 mixture of nitric acid (HNO3) and hydrofluoric acid (HF).
Scandium scandium earth Sc2O3 in ampoules has a specific gravity of 3.86, is more alkaline than aluminum oxide, weaker than yttrium oxide and magnesium oxide, and does not react with ammonium chloride. Salts are colorless and form colloidal precipitation with potassium hydroxide and sodium carbonate. It is difficult for all salts to crystallize well. Scandium salt is colorless, forms colloidal precipitation with potassium hydroxide and sodium carbonate, and sulfate is extremely difficult to crystallize. Carbonate is insoluble in water and may form alkaline carbonate precipitation.
Scandium carbonate is insoluble in water and easy to remove carbon dioxide. Sulfuric acid double salt may not form alum. The sulfuric acid double salt of scandium does not form alum. The volatility of anhydrous chloride ScCl3 is lower than that of aluminum chloride, and it is easier to hydrolyze than magnesium chloride. The sublimation temperature of ScCl3 is 850 ℃, while that of AlCl3 is 100 ℃, which is hydrolyzed in aqueous solution.
