The Shiny Element Scandium

Introduction to Scandium Element

Scandium is a soft, silver-colored rare earth element, found in group 3 of the periodic table. As a rare earth element, scandium is extremely malleable, conductive, and reactive. As a result of these characteristics, in addition to being lustrous, luminescent, and having the ability to act as strong permanent magnets, scandium commonly serves as an alloy with aluminum for airplane and sporting equipment.

Ten Fun Facts about Scandium

Lars Frederik Nelson and Per Teodor Cleve discovered scandium in Uppsala, Sweden (1879).
The element takes its name from the Latin word, Scandia, or Scandinavia.
Mendeleev predicted the existence of scandium, which he named eka-boron.
Scandium often coincides with other rare earth elements, like yttrium or ytterbium.
Scandium has similar chemistry to aluminum.
Scandium (III) triflate: inorganic catalyst for carbon-carbon bond forming reactions.
The scandium ion has a d⁰ configuration resulting in it forming colorless metal complexes.
The element is commonly found in the Earth’s crust.
Chemists don’t consider scandium as “rare” based on abundance. It actually has a similar abundance to cobalt.
Scandium only has one naturally occurring isotope, ⁴⁵Sc.

Scandium in the Periodic Table

Scandium has an atomic symbol of Sc. It has atomic number of 21 with an atomic weight of 44.95 amu. It’s electron configuration is [Ar]3d¹4s². It is a group 3 and period 4 element found in the d-block. Scandium’s electronegativity, according to the Pauling scale, is 1.36.

Where is Scandium found?

The minerals that scandium and other rare earth elements are often found in China, Kazakhstan, Madagascar, Norway and Russia. Scandium often comes in the form of scandium oxide, Sc₂O₃.

Isolating Scandium

As previously mentioned, you often find scandium as scandium oxide, Sc₂O₃, in the minerals thortveitite, kolbeckite, bazzite, jervisite, cascandite, juonniite, pretulite, scandiobabingtonite, and kristiansenite. To isolate scandium, scandium oxide converts to scandium fluoride.

Sc₂O₃ + 6HF → 2ScF₃ + 3H₂O

Then, a redox reaction occurs with calcium to isolate scandium.

2ScF₃ + 3Ca → 3CaF₂ + 2Sc

Modern Applications of Scandium

Scandium commonly serves in aluminum and titanium alloys. Scandium-aluminum alloys are used for lightweight sporting equipment, like baseball bats and lacrosse sticks. Scandium-titanium alloys are considered lighter and stronger compared to scandium-aluminum alloys. There is research exploring the possible use for scandium-titanium alloys in infrastructure. Likewise, scandium is used in metal halide lamps.

Metal Halide Lamps

Charles Proteus Steinmetz first worked to develop metal halide lamps in 1912. They are a type of big intensity discharge gas lamp, or (HID). Consumers commonly use these lights for indoor and outdoor lighting, automobile headlights, and indoor reef growing. Metal halide lamps, compared to LED lights, are less energy efficient, but more efficient than incandescent lamps.

The important parts of a metal halide lamp include the arc tube, outer bulb, base, and ballasts. Scandium is commonly found in the arc tube, where the light is generated. The arc tube has two electrodes made of tungsten doped with thorium are end to end with an AC voltage sealed with molybdenum sealed in silica. The light produced from the arc tube travels through a gaseous mixture of mercury and metal halides. The addition of scandium, sodium, thallium, or indium iodides or bromides result in different colored lights. General Electric developed scandium based metal halide lamps in the 1960s. Notably, scandium based metal halide lamps can mimic sunlight in film and television because of its intense white color.

Aside from the arc tube, the outer bulb prevents the heat produced from escaping and UV light from developing from the mercury vapor discharge. The base is commonly an Edison screw metal base, seen in incandescent and LED lights. The ballast regulates the current to extend the lifespan of the bulb. Due to the increase of current and decrease in voltage running through the arc tube, the ballast acts to reduce current.

The Discovery of Scandium

In 1869, Mendeleev proposed the existence of scandium as “eka-boron.” Scandium was discovered by two different research teams, one led by Lars Frederik Nilson and the other by Per Teodor Cleve in Uppsala, Sweden. Nilson’s team extracted scandium oxide in the minerals euxenite and gadolinite. Similarly, Cleve’s team found scandium in Uppsala. Per Teodor Cleve, with previous interactions with Mendeleev, notified Mendeleev on the existence of his proposed element.

Scandium Element Chemistry

Scandium Compounds and Reactions

Scandium halides: ScF₃ (insoluble in water), ScCl₃, ScBr₃, ScI₃
Scandium oxide: Sc₂O₃
Scandium hydroxide: Sc(OH)₃
Organoscanadium Compounds: (C₅Me₅)₂ScCl, [ScCp₂Cl]₂

Notably, scandium triflate, or scandium trifluoromethanesulfonate, serves as a Lewis acid catalyst for organic reactions. These reactions include Friedel-Crafts alkylation and Diels Adler, both of which are carbon-carbon bond-forming reactions.

Scandium Oxidation State

Unlike most transition metals, scandium does not have a wide range of oxidation states. Scandium commonly occupies in a 3+, Sc³⁺ or Sc (III). It occasionally occupies as an 0, 1+, and 2+ states when in an organoscanadium, an organometallic including scandium.

Properties of Scandium Element

Melting point: 1814 K; 1541 ºC; 2806 ºF
Boiling point: 3109 K; 2836 ºC; 5136 ºF
Density at STP: 2.985 g/cm³
Heat of fusion: 14.1 kJ/mol
Heat of vaporization: 332.7 kJ/mol
Molar heat capacity: 25.52 J/(mol*K)
Electronegativity: 1.36
Classification: Rare Earth Element; Transition Metal
Natural abundance on Earth: ~25 ppm
Electron configuration: [Ar]3d¹4s²
Found naturally in minerals: Thortveitite, Kolbeckite, Bazzite, Jervisite, Cascandite, Juonniite, Pretulite, Scandiobabingtonite, and Kristiansenite
Toxicity: Non-toxic

Where to buy Scandium Element?

The processing of scandium involves expensive processing; however, you purchase it online. Scandium oxide can range from $300 to about $1000 from MSE Supplies. Resellers on Ebay and Etsy sell scandium for about $25.