Date post: | 02-Jul-2015 |
Category: |
Education |
Upload: | cosnert-rabbani |
View: | 244 times |
Download: | 3 times |
History Of Scandium (Sc)
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.
EKA-BORON The name given by Mendeleyev in accordance with the periodic law, and by prediction, to
a hypothetical element then unknown, but since discovered and named scandium. so called because it was a missing analogue of the boron group.
The element was discovered by Nilsonin 1878 in the minerals euxenite and gadolinite, which had not yet been found anywhere except in Scandinavia.
euxenite and gadolinite is sources of this element
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.
Source Scandium is apparently much more abundant (the
23rd most) in the sun and certain stars than on earth (the 50th most abundant). 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.
How to extrat skandium? Pure scandium metal can be made by reacting
scandium fluoride (ScF3) with another active metal, such as calcium or zinc, eg,
3Ca + 2ScF3 3CaF2 + 2Sc
ReactionReaction of scandium with air
Scandium metal tarnishes in air and burns readily to form scandium (III) oxide, Sc2O3.
4Sc + 3O2 → 2Sc2O3
Reaction of scandium with water
When finely divided, or heated, scandium metal dissolves in water to form solutions containing the aquated Sc(III) ion together with hydrogen gas, H2.
2Sc(s) + 6H2O(aq) → 2Sc3+(aq) + 6OH-(aq) + 3H2(g)
Reaction of scandium with the halogens
Scandium is very reactive towards the halogens fluorine, F2, chlorine, Cl2 bromine, Br2, and iodine, I2, and burns to form the trihalides scandium(III) fluoride, ScF3 , scandium(III) chloride, ScCl3, scandium(III) bromide, ScBr3, and scandium(III) iodide, ScI3 respectively.
2Sc(s) + 3F2(g) → 2ScF3(s)
2Sc(s) + 3Cl2(g) → 2ScCl3(s)
2Sc(s) + 3Br2(g) → 2ScBr3(s)
2Sc(s) + 3I2(g) → 2ScI3(s)
Application About 20 kg of scandium (as Sc2O3) are used yearly in
the U.S. to produce high-intensity lights.
The radioactive isotope 46 Sc 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.
Continue.. The original use of scandium-aluminium alloys was in
the nose cones of some Soviet submarine-launched ballistic missiles (SLBM).
Scandium alloys are especially desirable for use in, for example, baseball bats, lacrosse sticks, and bicycle frames.
Fuel cells