Chemical Properties
grey powder
Physical properties
Scandium is a soft, lightweight, silvery-white metal that does not tarnish in air, but overtime, it turns yellowish-pink. It resists corrosion. Scandium reacts vigorously with acids, butnot water. Scandium has some properties similar to the rare-earth elements. Although its position in group 3 places it at the head of the 17 elements of the lanthanide series of rare-earthmetals, scandium, as a metal, is not usually considered a rare-earth. Scandium’s melting pointis 1,541°C, its boiling point is 2836°C, and its density is 2.989 g/cm3.
Isotopes
There are 28 isotopes of scandium, ranging from scandium-36 to scandium-57.Scandium-45 is the only stable isotope and contains about 100% of the natural scandium found in the Earth’s crust. The remaining isotopes are radioactive with half-livesranging from nanoseconds to a few minutes to a few hours to a few days, and therefore,they are not found naturally in the Earth’s crust. The radioactive isotopes of scandiumare produced in nuclear reactors.
Origin of Name
From the Latin word Scandia, for “Scandinavia.
Occurrence
Although scandium is chemically similar to rare-earths, it no longer is considered to be oneof them. Scandium is the 42nd most abundant element found in the Earth’s crust, makingup about 0.0025% of the Earth’s crust. It is widely distributed at 5 ppm on the Earth. (It isabout as abundant as lithium, as listed in group 1.) Scandium is even more prevalent in thesun and several other stars than it is on Earth.Scandium is found in ores of wolframite in Norway and thortveitite in Madagascar. It isalso found in granite pegmatites and monazites. It is common in many of the ores where tinand tungsten are also found.
Characteristics
Scandium is the first element in the fourth period of the transition elements, which meansthat the number of protons in their nuclei increases across the period. As with all the transition elements, electrons in scandium are added to an incomplete inner shell rather than tothe outer valence shell as with most other elements. This characteristic of using electrons inan inner shell results in the number of valence electrons being similar for these transition elements although the transition elements may have different oxidation states. This is also whyall the transition elements exhibit similar chemical activity.
Definition
A lightweight
silvery element belonging to the first transition
series. It is found in minute amounts
in over 800 minerals, often associated with
lanthanoids. Scandium is used in high-intensity
lights and in electronic devices.
Symbol: Sc; m.p. 1541°C; b.p. 2831°C;
r.d. 2.989 (0°C); p.n. 21; r.a.m.
44.955910.
Definition
scandium: Symbol Sc. A rare softsilvery metallic element belonging togroup 3 (formerly IIIA) of the periodictable; a.n. 21; r.a.m. 44.956; r.d.2.989 (alpha form), 3.19 (beta form);m.p. 1541°C; b.p. 2831°C. Scandiumoften occurs in lanthanoid ores,from which it can be separated on accountof the greater solubility of itsthiocyanate in ether. The only naturalisotope, which is not radioactive,is scandium–45, and there are nineradioactive isotopes, all with relativelyshort half-lives. Because of themetal’s high reactivity and high costno substantial uses have been foundfor either the metal or its compounds.Predicted in 1869 by DmitriMendeleev, and then called ekaboron,the oxide (called scandia) wasisolated by Lars Nilson (1840–99) in1879.
Hazard
As with other metals, the transition metals and many of their compounds are toxic, andtheir powdered or gaseous forms should not be ingested or inhaled. In addition, all but one ofthe isotopes of scandium are radioactive and should be handled by experienced personnel.
Toxicity evaluation
Scandium is considered non-toxic, though extensive animal testing of scandium compounds has not been done.The median lethal dose (LD50) levels for scandium chloride for rats have been determined as 755 mg/kg for intraperitoneal and 4 g/kg for oral administration.Compounds of scandium should be handled as compounds of moderate toxicity.
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