Scandium

escandio

Scandium emits no lines in the visible region of the electromagnetic spectrum. Nevertheless, scandium can be detected by its lines in other regions of the spectrum. Until the beginning of the 20th century, scandium was thought to be one of the rarest elements on Earth. In 1908, however, the British chemist Sir William Crookes (1832–1919) discovered that scandium actually is widely distributed on Earth. Scandium is often recovered from uranium tailings.

Scandium is a soft, light metal similar to aluminum. It is so rare on Earth that it is very difficult to obtain large quantities of this element. Scandium is only used for very specialized applications. The main ores in which it is found are gadolinite and euxenite, which also contain small amounts of many other rare metals, such as cerium and yttrium. Scandium mixed with aluminum produces a very strong alloy, used in lightweight sports equipment such as lacrosse. It is also used in the manufacture of high-speed turbines in fighter aircraft.

Chemical properties

Scandium has a density of 3.0 g/cm3, it is a soft metal, and a silver colored.

Although scandium has no known biological function, however, very small (trace) amounts can be measured in parts per billion (ppb) concentrations in human blood and tissues.

Scandium is a fairly reactive element. It dissolves in water and most acids to form the Sc3+ ion. It reacts with atmospheric oxygen at normal temperatures. In nature, scandium readily forms an insoluble hydroxide (Sc(OH)3). In the laboratory, a hydride of formula ScH2 can be obtained, suggesting that the scandium ion is only Sc2+. Why the scandium hydride is not "+3" instead of "+2" is unknown. The scandium ion (Sc3+) forms compounds with the most common monovalent anions (ions with charges of "-1"). Thus, Sc(NO3)3 is easily formed, and with the halogens: ScF3, ScCl3, ScBr3 and ScI3. All these compounds are white and soluble in water.

Summary of properties (Sc)

Atomic weight44.955908(5)
Discoverer (year)Nilson, Lars Fredrik (1879)
Natural formmetallic solid (hexagonal)
Electron configuration[Ar] 3d1 4s2
Melting point (ºC)1539
Boiling point (ºC)2832
Abundance in earth's crust (ppm)22
Isotope (abundance)45Sc (100)
Density g/cm33.00
Van der Waals radius (pm)215
Covalent radius (pm)159
Electronegativity (Pauling)1.54
Vaporization enthalpy (kJ/mol)305.00
Enthalpy of fusion (kJ/mol)14.10
Specific heat capacity (J/g·K) at 25ºC and 1 atm0.57
Thermal conductivity (W/cm·K) at 25ºC and 1 atm0.160
Oxidation state+3
Electron affinity (eV)0.19
1st Ionization potential (eV)6.5615

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