Скандий

Химические свойства

grey powder

Физические свойства

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.

Изотопы

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.

Происхождение имени

From the Latin word Scandia, for “Scandinavia.

Вхождение

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.

Характеристики

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.

Использование

Scandium was not produced in any quantities until the late 1930s. Its light weight,resistance to corrosion, and high melting point made it especially useful in the aerospaceindustries. In the early 1940s contractors for the U.S. Air Force appropriated almost all of thescandium metal for use in the construction of military aircraft. The pure metal form is produced by the electrolysis of a salt of scandium, ScCl₃. The metal has found some other uses in high-intensity lamps that produce a natural spectrum, making it useful for stadium lighting.It is also used in nickel alkaline storage batteries. Several compounds are used as catalysts tospeed up chemical reactions. The radioactive scandium-46 (with a half-life of 83.8 days) emitsbeta radiation. This property makes it useful as a radioactive tracer in the petroleum industryto monitor fractionation products.

Определение

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.

Опасность

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.