Sc
44.956Scandium
Skandiyum
Scandium is a light transition metal with atomic number 21. It is best known for aluminum-scandium alloys, high-intensity lamps, scandia-stabilized ceramics and its role as one of Mendeleev’s predicted elements.
21
44.956 g/mol
[Ar] 3d¹ 4s²
2 | 8 | 9 | 2
1.36
2.985 g/cm³
1540.8 °C
2835.8 °C
Lars Fredrik Nilson
Scandium was discovered in 1879 by Lars Fredrik Nilson while analyzing rare minerals from Scandinavia. Its properties closely matched Mendeleev’s predicted element eka-boron, helping confirm the predictive power of the periodic table.
Scandium-45
Natural abundance: 100%. The only stable naturally occurring isotope of scandium.Scandium-46
Natural abundance: Synthetic. Half-life: About 83.8 days. Radioactive isotope used as a tracer in industrial studies.Sc₂O₃
Scandium OxideUsed in specialized ceramics, optical coatings and scandia-stabilized zirconia.ScCl₃
Scandium ChlorideLewis acid and precursor for scandium chemistry.ScI₃
Scandium IodideAdded to metal halide lamps to improve light quality.ScF₃
Scandium FluorideStudied for unusual thermal expansion behavior and specialty materials.- Aluminum-scandium alloys for lightweight, strong aerospace and sports equipment
- Scandium iodide in metal halide lamps to improve bright white light quality
- Scandium oxide in specialized ceramics and optical coatings
- Scandia-stabilized zirconia electrolytes in solid oxide fuel cells
- Scandium-46 radioactive tracer work in industrial flow and leak studies
Scandium has no known essential biological role in humans. Trace amounts can occur in some organisms, but scandium is not considered a required nutrient.
- Scandium was one of the classic confirmations of Mendeleev’s periodic table predictions.
- Although scandium is not extremely rare in Earth’s crust, it is difficult and expensive to extract in concentrated form.
- Small scandium additions can significantly strengthen aluminum alloys.
- Sc³⁺ has an empty d shell, so many scandium compounds are colorless compared with typical transition metal ions.
- Scandium has atomic number 21 and starts the 3d transition metal series in period 4.
- Its electron configuration is [Ar] 3d¹ 4s².
- The most common oxidation state is +3.
- Scandium is often discussed with Mendeleev’s eka-boron prediction because its oxide and properties matched the forecast closely.
What is the atomic number of scandium?
The atomic number of scandium is 21.
What is the electron configuration of scandium?
Scandium has the electron configuration [Ar] 3d¹ 4s².
What is scandium used for?
Scandium is used in aluminum-scandium alloys, high-intensity lamps, specialized ceramics, optical coatings and solid oxide fuel cell materials.
Why was scandium important for Mendeleev’s periodic table?
Scandium matched the properties Mendeleev predicted for eka-boron, proving that the periodic table could predict undiscovered elements.
What is the main isotope of scandium?
Scandium-45 is the only stable naturally occurring isotope of scandium.
Why are scandium compounds often colorless?
Sc³⁺ has an empty d shell, so it lacks the d-d electronic transitions that make many transition metal ions colored.