What is scandium?
Scandium is a chemical element or transition metal of Group 3 of the periodic table with atomic number 21 and symbol Sc. It has only one common oxidation number or state +3 due to the presence of three valence electrons. Scandium is a silvery-white, moderately soft metal that usually occurs with the lanthanides due to the lack of the characteristics of transition metals. The chemistry of scandium resembles the metal aluminum. Therefore, Russian chemist Dmitry Ivanovich Mendeleyev named it ekaboron.
Where is scandium found?
In the earth’s crust, scandium is not rare, it is found with the lanthanides and uranium ore (0.02 percent of Sc2O3) which may be obtained as a by-product. Thortveitite (Sc2SiO7) is a mineral of scandium found mostly in Norway.
Scandium on the periodic table
Scandium, yttrium, and lanthanum constitute group-3 of the periodic table. They are the beginning members of the first three transition series. They have a d1 s2 electronic configuration over a closed noble gas shell.
Properties of scandium
The silvery-white hexagonal crystal lattice, scandium has the valence shell electronic configuration [Ar] 3d1 4s2. The common oxidation number or state of metal +3 with no d-electron. Some physical and chemical properties of metal are given below the table,
|Properties of Scandium
|Electronic configuration||[Ar] 3d1 4s2|
|Crystal structure||hexagonal closed packed|
|Heat capacity||25.52 J mol-1 K-1|
|Melting point||1539 °C|
|Boiling point||2836 °C|
|Electronegativity||1.36 (Pauling scale)|
Scandium minerals 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 the 23rd abundant element in sun due to its high cosmic abundance.
Isotopes of element
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 of fewer 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.
Facts about scandium
- The chemistry and facts of scandium resemble very closely with element aluminum. Both the metals are dominated by +3 state or form trivalent ions like Al+3 and Sc+3.
- It is less electropositive than preceding group member calcium.
- Scandium is a transition element due to the presence of a d electron. However not many of the properties (variable oxidation number) associated with Sc. Therefore, it behaves more like non-transition metals.
- Sc 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.
- Nitrogen combines with it at high temperatures to form ScN, which on hydrolysis by water.
Halogens like fluorine, chlorine, and bromine react with scandium to form ionic halides (ScX3). 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 contain a layer structure.
Scandium(III) oxide or scandia is an oxide of metal that has the chemical formula Sc2O3. It is amphoteric in nature. Sc2O3 dissolved in acids to give Sc(III) salts. In excess NaOH, it gives Na3[Sc(OH)6]-3.
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 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.