Scandium
Atomic Data
| Atomic Number | 21 |
| Symbol | Sc |
| Atomic Weight | 44.956 u |
| Density (STP) | 2.985 g/cm³ |
| Melting Point | 1540.85 °C (1814 K) |
| Boiling Point | 2835.85 °C (3109 K) |
| Electronegativity | 1.36 (Pauling) |
| Electron Config. | 1s2 2s2 2p6 3s2 3p6 3d1 4s2 |
| Oxidation States | +3 |
| Phase at STP | Solid |
| Category | Transition Metal |
| Period / Group | 4 / 3 |
| CAS Number | 7440-20-2 |
Electron Configuration
[Ar] 3d1 4s2
| Shell | n | Subshell | Electrons | Cumulative |
|---|---|---|---|---|
| K | 1 | 1s | 2 | 2 |
| L | 2 | 2s | 2 | 4 |
| L | 2 | 2p | 6 | 10 |
| M | 3 | 3s | 2 | 12 |
| M | 3 | 3p | 6 | 18 |
| M | 3 | 3d | 1 | 19 |
| N | 4 | 4s | 2 | 21 |
| Total | 21 | 21 | ||
Isotopes of Scandium
Scandium has only one naturally occurring isotope, 45Sc, which is entirely stable and accounts for 100% of all natural scandium. All other known isotopes of scandium are radioactive and produced artificially.
| Isotope | Symbol | Protons | Neutrons | Abundance | Stability |
|---|---|---|---|---|---|
| Scandium-45 | ⁴⁵Sc | 21 | 24 | 100% | Stable |
Abundance & Occurrence
Scandium occurs at about 22 ppm in Earth's crust, making it more abundant than lead, yet it is so widely dispersed across many minerals that no economically viable concentrated ore deposits have historically been exploited. It is found in association with rare earth minerals such as thortveitite, euxenite, and gadolinite, and is also recovered as a by-product of uranium and titanium processing.
Earth's Crust (ppm by mass)
Universe (ppm by mass)
Discovery & History
Safety & Handling
- Toxicity: Scandium and its compounds are considered mildly toxic. The element presents a low acute hazard in metallic form but should not be ingested or inhaled as dust.
- Skin and Eye Irritation: Scandium compounds such as scandium chloride and scandium oxide may cause irritation to skin and eyes on prolonged contact. Gloves and safety glasses are recommended when handling these materials in the laboratory.
- Inhalation Hazard: Fine scandium metal powder and scandium compound dusts should not be inhaled. Adequate ventilation or respiratory protection is advised when machining or processing scandium in powdered form.
- Fire Hazard: Bulk scandium metal is not spontaneously flammable under normal conditions. Finely divided scandium powder can be combustible and should be kept away from ignition sources.
- Storage: Scandium metal should be kept in a cool, dry place away from strong acids and oxidising agents. Scandium compounds should be stored in sealed containers to prevent moisture absorption.
Scandium in the Real World
Real-World Uses
- Aluminium-scandium alloys for aerospace — Adding as little as 0.1–0.5% scandium to aluminium alloys substantially increases their tensile strength, corrosion resistance, and weldability. These alloys are used in aircraft fuselage components, rocket bodies, and military aircraft where weight savings and structural integrity are both critical.
- High-intensity metal halide lamps — Scandium iodide is added to high-intensity discharge lamps to produce bright, white light with a colour rendering index close to natural sunlight. These lamps illuminate sports stadiums, film and television sets, and large indoor arenas worldwide.
- Radioactive tracers — The radioactive isotope scandium-46 is used as a tracing agent in oil refinery research to study fluid flow and the efficiency of petroleum cracking catalysts, enabling engineers to optimise processes without physically dismantling equipment.
- Solid oxide fuel cells — Scandia-stabilised zirconia (ScSZ) is a high-performance electrolyte material used in solid oxide fuel cells (SOFCs). Its superior ionic conductivity at operating temperatures makes it a leading candidate for next-generation clean energy applications.
- Sports equipment alloys — Aluminium-scandium alloy tubing is used in premium bicycle frames, baseball bats, lacrosse sticks, and other sporting goods where light weight, high strength, and vibration damping are valued by competitive athletes.
Downloadable Resources
Free periodic table reference sheets for classrooms, study sessions, and laboratory use.
Frequently Asked Questions
What is scandium used for?
Scandium's primary use is in aluminium-scandium alloys, which are significantly stronger and lighter than standard aluminium alloys and are used in aerospace components, bicycle frames, and high-end sports equipment. It is also used in high-intensity metal halide lamps that produce light closely matching natural sunlight, as a radioactive tracer in oil refinery research, and in solid oxide fuel cells.
Who discovered scandium and when?
Scandium was discovered in 1879 by Swedish chemist Lars Fredrik Nilson, who isolated it from the minerals euxenite and gadolinite. Nilson named the element after Scandinavia. Notably, its existence had been predicted eight years earlier by Dmitri Mendeleev, who called the unknown element "ekaboron" based on gaps in his periodic table.
Is scandium a rare earth element?
Scandium is sometimes grouped with the rare earth elements (lanthanoids) due to its similar chemical behaviour and geological occurrence, but it is not a lanthanoid. It is a transition metal in Group 3, Period 4. Scandium is genuinely rare, with a crustal abundance of about 22 ppm, and is difficult to extract commercially because it is widely dispersed rather than concentrated in economically viable deposits.
How many isotopes does scandium have?
Scandium has only one naturally occurring isotope, scandium-45 (⁴⁵Sc), which is completely stable. All other known isotopes of scandium are radioactive with short half-lives and are produced artificially.