Scandium is a chemical element with the atomic number 21 in the periodic table. With 22 parts-per-million abundance by weight, it’s the 31st most abundant element in Earth’s crust.
Being a member of the transition metals family of periodic table elements, this rare-earth chemical element has three valence electrons and can be found in plenty of minerals. But even so, scandium is classified as a relatively rare substance due to the difficult processing of the scandium-rich minerals. Having the strength of titanium, the lightness of aluminum, and the hardness of ceramics, scandium is adopted in only a few commercial applications.
Chemical and Physical Properties of Scandium
The symbol in the periodic table of elements: Sc
Atomic number: 21
Atomic weight (mass): 44.9559 g.mol-1
Group number: 3
Period: 4 (d-block)
Color: Silvery-white metal
Physical state: Solid at room temperature
Half-life: From less than 300 nanoseconds to 83.79(4) days
Electronegativity according to Pauling: Unknown
Density: 3.0 g.cm-3 at 20°C
Melting point: 1541°C, 2806°F, 1814 K
Boiling point: 2836°C, 5137°F, 3109 K
Van der Waals radius: 0.161 nm
Ionic radius: 0.083 nm (+3)
Most characteristic isotope: 45Sc
Electronic shell: [Ar] 3d14s2
The energy of the first ionization: 640.5 kJ.mol-1
The energy of the second ionization: 1233 kJ.mol-1
The energy of the third ionization: 2389 kJ.mol-1
The energy of the fourth ionization:7089 kJ.mol -1
Discovery date: In 1879 by Lars Fredrik Nilson
With the periodic table symbol Sc, atomic number 21, atomic mass of 44.9559 g.mol-1, and electron configuration [Ar] 3d14s2, scandium is a soft and light silvery-white metal, classified as a rare-earth chemical element in the periodic table.
Scandium reaches its boiling point at 2836°C, 5137°F, 3109 K, while the melting point is achieved at 1541°C, 2806°F, 1814 K. This member of the transition metals family of elements has an unknown electronegativity according to Pauling, whereas the atomic radius according to van der Waals is 0.161 nm.
Element 21 has a hexagonal crystal structure and paramagnetic properties. When exposed to air, scandium is very reactive and tarnishes into a yellowish or pinkish color. In a reaction with H2O, this transition metal forms hydrogen gas.
How Was Scandium Discovered?
While classifying the predicted elements in his periodic table, the great Russian chemist Dmitri Mendeleev noticed a gap in the atomic weights between the elements calcium (40) and titanium (48). According to his chemical calculations, the oxide of the predicted “eka-boron” element with an atomic mass fitting somewhere between calcium and titanium would be X2O3.
The Discovery of Lars Frederik Nilson
Ten years later, professor Lars Fredrik Nilson (1840 – 1899) from the Uppsala University in Sweden started to extensively research rare-earth elements. In one of his chemical trials, Nilson extracted ytterbium from the minerals euxenite and gadolinite. For this, he first isolated erbia (erbium oxide) from the minerals. In the next step of the experiment, the Swedish chemist triggered a chemical reaction that resulted in erbium nitrate.
When professor Nilson heated the nitrate, he observed small quantities of an unknown metallic element with a low atomic weight. The second oxide turned out to be Sc2O3, corresponding to Mendeleev’s prediction about element 21. Also, the atomic weight of the new chemical was 44, which is exactly in the middle of the boundary elements that Mendeleev had suggested.
By using the spectroscopy method on the sample, Nilson determined the existence of a new element whose atomic spectrum displayed over 30 unique spectral lines.
The Contribution of Per Theodor Cleve
The chemical analysis performed by the Swedish chemist and mineralogist Per Theodor Cleve (1840-1905) successfully proved that scandium had properties similar to those predicted by Mendeleev for the element labeled as eka-boron.
How Did Scandium Get Its Name?
The name of element 21, scandium, originates from the Latin word for Scandinavia, “Scanda”. The Swedish scientist and discoverer Lars Fredrik Nilson chose this name for the new element as a way to relate it with the area where the scandium-rich minerals have initially been found. It’s also a nod to Nilson’s country of origin.
Where Can You Find Scandium?
Despite being labeled as a rare-earth element, scandium is a relatively abundant chemical. It typically occurs in the same ores alongside other rare-earth elements. However, pure scandium metal rarely concentrates at higher grades alongside other metals.
For this reason, commercially usable scandium deposits are very rare. Also, it’s highly difficult to separate the rare-earth elements that occur in the same mineral ore because they share very similar chemical properties.
The first metal sample of scandium was isolated from a mixture of scandium, lithium, and potassium chloride by the German chemists Werner Fischer, Karl Brünger, and Hans Grienseisen. The process included molten zinc in a graphite cubicle from which the metal form of element 21 was extracted by electrolysis. Metallic scandium can also be prepared by reducing the fluoride with calcium metal. The first pound of high purity scandium was obtained in 1960.
For commercial purposes, scandium is mostly obtained as a byproduct of refining uranium. Australia, especially New South Wales, is marked as a location richest in scandium mineral sources. Deposits of gadolinite and euxenite are also found in Scandinavia, South Africa, Madagascar, and India. At the mining sites open in Russia, China, and Ukraine, scandium is obtained as a byproduct of iron and uranium mining.
List of Scandium Minerals
Element 21 has been thinly scattered in over 800 minerals. The mineral thortveitite is considered the main source of scandium. It’s frequently found in granitic pegmatites. The other most commonly occurring scandium-rich minerals include:
Scandium in Everyday Life
As the isolation of this chemical element from the scandium-bearing ores is a highly difficult and laborious process, it adds both to the rarity of scandium as well as to the limited number of its practical uses.
- Element 21 is used in the aerospace industry to manufacture aluminum alloys for lightweight aircraft and automobiles. When scandium is added to these alloys, it provides stronger, more corrosion-resistant, heat-tolerant, and weldable material;
- Aluminum-scandium alloys are applied in the production of sports equipment, such as aluminum baseball bats, bicycle frames, and lacrosse sticks. Sc-Al alloys are also used for the production of fuel cells;
- Approximately 20 kilograms (44 pounds) of scandium oxide (Sc2O3), or scandia, are used per year in the United States for the production of high-intensity lights;
- Some of the most popular everyday uses of scandium include its application in the manufacturing of glasses, energy-saving bulbs and lamps, fluorescent lamps, as well as TV sets;
- Erbium-chromium-doped yttrium-scandium-gallium garnet (Er,Cr:YSGG) lasers are used in dentistry for cavity preparation and in endodontics;
- Scandium-46 isotope is included in the oil industry processes and oil refineries;
- In order to produce light resembling the one emitted by the Sun, scandium iodide (ScI3) is added to mercury vapor lamps.
How Dangerous Is Scandium?
This chemical element is generally considered to have low toxicity. Scientists suspect that scandinavium could possibly be a carcinogenic chemical element. However, there aren’t sufficient studies of the scandinavium effects on human health due to its rarity in nature. As a precaution, all routes of scandinavium exposure should be avoided.
Environmental Effects of Scandium
Scandium has no known biological role. However, it can easily become an environmental pollutant if released uncontrollably by the industries that use this chemical in their production processes.
Isotopes of Scandium
Element 21 has 23 observed isotopes, ranging from scandium-39 to scandium-61. The naturally occurring scandium consists of one stable isotope, 45Sc. There are also 25 radioactive isotopes of this transition metal.
The primary decay modes of the scandium isotopes are beta plus, beta minus, or electron capture. While the isotopes at atomic weights below 45Sc decay into calcium isotopes, the isotopes of scandium at atomic weights above 45Sc decay into forms of titanium.
|Z||N||Isotopic mass (Da)
[n 2][n 3]
[n 7][n 4]
|Natural abundance (mole fraction)|
|Excitation energy||Normal proportion||Range of variation|
|40Sc||21||19||39.977967(3)||182.3(7) ms||β+ (99.54%)||40Ca||4-|
|β+, p (.44%)||39K|
|β+, α (.017%)||36Ar|
|53Sc||21||32||52.95961(32)#||2.4(0.6) s||β− (>99.9%)||53Ti||(7/2−)#|
|β−, n (<.1%)||52Ti|
|54Sc||21||33||53.96326(40)||260(30) ms||β− (>99.9%)||54Ti||3+#|
|β−, n (<.1%)||53Ti|
|55Sc||21||34||54.96824(79)||0.115(15) s||β− (>99.9%)||55Ti||7/2−#|
|β−, n (<.1%)||54Ti|
|59Sc||21||38||58.98922(97)#||10# ms||β−, n||58Ti||7/2−#|
List of Scandium Compounds
The most commonly adopted oxidation state of scandium is +3, even though this chemical can also occur in other oxidation states. Element 21 forms organic derivatives, pseudohalides, halides, hydroxides, and oxides. Some of the most studied scandium compounds include:
- Lead scandium tantalate
- Scandium bromide
- Scandium chloride
- Scandium dodecaboride
- Scandium fluoride
- Scandium hydride
- Scandium monosulfide
- Scandium nitrate
- Scandium nitride
- Scandium oxide
- Scandium perchlorate
- Scandium sulfate
- Scandium triiodide
- Scandium(III) hydride
- Scandium(III) hydroxide
- Scandium(III) sulfide
- Scandium(III) trifluoromethanesulfonate
5 Interesting Facts and Explanations
- Scandium metal occurs more abundantly in Earth’s crust than lead, mercury, and all the precious metals.
- Since there are no mines in the world that produce only scandium, this element is classified as a relatively rare one.
- Euxenite is a complex mineral that contains eight metal oxides.
- Nilson used 10 kilograms of the mineral euxenite ((Y, Ca, Er, La, Ce, U, Th)(Nb, Ta, Ti)2O6) to obtain the ytterbia sample from which he later managed to isolate the new chemical element scandium.
- Scandinavium gives the blue color to aquamarine gems.