Scandium is a chemical element with symbol Sc and atomic number 21. Classified as a transition metal, Scandium is a solid at room temperature. Naturally occurring scandium (21 Sc) is composed of one stable isotope, 45 Sc. Twenty-five radioisotopes have been characterized, with the most stable being 46 Sc with a half-life of 83.8 days, 47 Sc with a half-life of 3.35 days, and 48 Sc with a half-life of 43.7 hours and 44 Sc with a half-life of 3.97 hours. All the remaining isotopes have half-lives that are less than four hours, and the.
Scandium is a silver-white hard metal which develops a slightly yellowish or pinkish cast upon exposure to air. |
Scandium
Atomic Number: | 21 | Atomic Radius: | 211 pm (Van der Waals) |
Atomic Symbol: | Sc | Melting Point: | 1541 °C |
Atomic Weight: | 44.96 | Boiling Point: | 2836 °C |
Electron Configuration: | [Ar]4s23d1 | Oxidation States: | 3, 2,[2] 1[3] (an amphoteric oxide) |
History
From the Latin word Scandia, Scandinavia. On the basis of the Periodic System, Mendeleev predicted the existence of ekaboron, which would have an atomic weight between 40 of calcium and 48 of titanium.The element was discovered by Nilson in 1878 in the minerals euxenite and gadolinite, which had not yet been found anywhere except in Scandinavia. By processing 10 kg of euxenite and other residues of rare-earth minerals, Nilson was able to prepare about 2g of highly pure scandium oxide. Later scientists pointed out that Nilson's scandium was identical with Mendeleev's ekaboron.
Sources
Scandium is apparently much more abundant (the 23rd most) in the sun and certain stars than on earth (the 50th most abundant). It is widely distributed on earth, occurring in very minute quantities in over 800 mineral species. The blue color of beryl (aquamarine variety) is said to be due to scandium. It occurs as a principal component in the rare mineral thortveitite, found in Scandinavia and Malagasy. It is also found in the residues remaining after the extraction of tungsten from Zinnwald wolframite, and in wiikite and bazzite.
Most scandium is presently being recovered from thortveitite or is extracted as a by-product from uranium mill tailings. Metallic scandium was first prepared in 1937 by Fischer, Brunger, and Grienelaus who electrolyzed a eutectic melt of potassium, lithium, and scandium chlorides at 700 to 800°C. Tungsten wire and a pool of molten zinc served as the electrodes in a graphite crucible. Pure scandium is now produced by reducing scandium fluoride with calcium metal.
The production of the first pound of 99% pure scandium metal was announced in 1960.
Properties
Scandium is a silver-white metal which develops a slightly yellowish or pinkish cast upon exposure to air. A relatively soft element, scandium resembles yttrium and the rare-earth metals more than it resembles aluminum or titanium.
It is a very light metal and has a much higher melting point than aluminum, making it of interest to designers of spacecraft. Scandium is not attacked by a 1:1 mixture of HNO3 and 48% HF.
Chemically it is one of the alkaline earth elements; it readily forms a white coating of nitride in air, reacts with water, burns with a yellow-red flame.
Uses
About 20 kg of scandium (as Sc2O3) are used yearly in the U.S. to produce high-intensity lights. The radioactive isotope 46Sc is used as a tracing agent in refinery crackers for crude oil, etc.
Scandium iodide added to mercury vapor lamps produces a highly efficient light source resembling sunlight, which is important for indoor or night-time color TV.
Who Discovered Scandium
Handling
Little is yet known about the toxicity of scandium; therefore it should be handled with care.
Scandium is a soft, silvery metallic element. Its atomic number is 21, making it the lightest of the transition metals. Scandium is not particularly rare - its occurrence in crustal rocks is 22 around ppm. This makes scandium generally more abundant than lead, mercury, and precious metals. Despite this fairly common occurrence, scandium rarely concentrates in nature. It does not selectively combine with the common ore-forming anions, so time and geologic forces only rarely form scandium concentrations over 100 ppm. There is currently no dedicated single mine source and it estimated that only 15 tonnes of scandium are produced globally each year.
Scandium exists in nature in its oxide form. It is very difficult to reduce to its pure elemental state. In fact, it was not isolated in pure form until 1937 and the first pound of pure elemental scandium metal was not produced until 1960. Scandium in oxide form is referred to as scandia or scandium oxide, and the chemical formula is Sc2O3. Processed scandium oxide, a white powder, is stable at ambient temperature and is the standard scandium form for commerce.
Despite scandium’s scarcity and high cost, interest in the metal is high and multiple high value commercial uses have been developed. Of particular interest is the alloy of scandium into aluminum metal products. When used in combination with other common aluminum alloys scandium can produce stronger, more corrosion resistant, heat tolerant, weldable aluminum products. Aluminum products are being increasingly incorporated into transportation applications (aircraft and automobile) in order to meet fuel efficiency requirements.
How Many Shells Does Scandium Have
Aircraft manufacturers are particularly interested in scandium alloyed aluminum materials. Aircraft designers believe use of Al-Sc alloys can reduce aircraft weights by 15%-20%. In addition, the ability to employ weldable structures promises similar cost reduction potential.
Scandium also exhibits exceptional electrical conductivity and heat stabilization qualities and the largest volume current use is in solid oxide fuel cells (“SOFCs”). Incorporation of scandium in SOFCs enables a lower operating temperature resulting in longer lived equipment and less costly materials of construction. Bloom Energy is the leading SOFC manufacturer and currently single largest scandium user.
Al-Sc alloys may reduce aircraft weights by 15%-20%
Sc Element
Numerous other applications have been identified and are under research, most notably high intensity lighting (“stadium lighting”) and high voltage power transmission and additive layer parts manufacturing (“3D Printing”).