Scandium in Periodic Table
Scandium (Sc), chemical element or rare-earth metal of Group 3 of the periodic table has only one common oxidation number or state +3 with no d-electron. Scandium is a silvery-white, moderately soft metal that usually occurs with the lanthanides due to the lack of the characteristics of transition elements. The chemistry of scandium resembles the metal aluminum and Russian chemist Dmitry Ivanovich Mendeleyev named it ekaboron.
The silvery-white hexagonal crystal lattice, scandium has the chemical symbol Sc, atomic number 21, atomic weight 44.956, melting point 1539 °C, boiling point 2836 °C, density 2.985 gm/cm3, and valence shell electronic configuration [Ar] 3d1 4s2. The common oxidation number or states of metal +3 with no electron in the valence d-orbitals.
Occurrence and Isotopes
In the earth’s crust, scandium is not rare, it occurs with the lanthanides and uranium ore (0.02 percent of Sc2O3) which may be obtained as a by-product. Thortveitite (Sc2SiO7) is a rare mineral of scandium that found mostly in Norway. The mineral may be treated similarly to bauxite to obtained insoluble ScO(OH) and dehydration of Hydrous oxide to form Sc2O3. The metal is obtained by the electrolysis of a molten mixture of scandium trichloride (ScCl3), potassium chloride (KCl), and lithium chloride (LiCl). It is the 50th most abundant element in the earth’s environment and 23rd abundant element in sun due to its high cosmic abundance.
In nature, 45Sc is the most stable isotope of scandium. It also has thirteen unstable short lives radioactive isotopes with atomic masses ranging from 36 to 61. 46Sc is the most stable radioactive isotope (half-life of 83.8 days) and 39Sc is the least stable isotope with a half-life less than 300 nanoseconds. Primarily, calcium or titanium isotopes are formed by the radioactive decay of scandium isotopes. Atomic mass below 46 primarily formed calcium isotopes and above 46 formed titanium isotopes by nuclear reaction.
Chemistry and Chemical Properties
The chemistry and properties of scandium resemble very closely with aluminum and are dominated by +3 state or trivalent ion like Sc+3. It dissolves in both acids and alkalis but does not react with the 1:1 mixture of nitric acid and hydrofluoric acid due to the formation of protective layers. Halogens like fluorine, chlorine, and bromine react with scandium to form ionic halides (ScX3). Nitrogen combines with it at high temperatures to form ScN, which on hydrolysis by water. ScF3, the only insoluble halide that dissolved in ammonium fluoride or alkali metal fluoride to give octahedral [ScF6]-3 ions. The trichloride like ScCl3 is isostructural with AlCl3. The reaction of ScCl3 with excess scandium at high temperature gives lower halides (ScCl) which contains a layer structure.
Uses of Scandium
Scandium alloy is strong like titanium and light like aluminum and used for the production of the components of aerospace, sports equipment, baseball bats high performing materials, and bicycle frames. The alloy is used in the Russian military aircraft like MIG-21 and MiG-29. The radioactive isotopes 46Sc uses as a tracer in the oil refinery process. In the United States and major industrial-based counties, scandium halide lamps for the production of highly efficient light like sunlight which is widely used in the television industry.