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21Sc44.96

Element 21, a transition metal

Scandium

A light, rare metal that Mendeleev predicted before anyone found it, now used to strengthen the aluminum in bike frames and baseball bats.

At a glance

Symbol
Sc
Atomic number
21
Average atomic mass
44.96
Group
3
Period
4
Family
transition metal
Electron configuration
[Ar] 3d¹ 4s²
Electronegativity
1.36
Common ions
Sc³⁺

On the table

Periodic table with Scandium highlighted123456789101112131415161718123456757-7189-103HHeLiBeBCNOFNeNaMgAlSiPSClArKCaScTiVCrMnFeCoNiCuZnGaGeAsSeBrKrRbSrYZrNbMoTcRuRhPdAgCdInSnSbTeIXeCsBaLaCePrNdPmSmEuGdTbDyHoErTmYbLuHfTaWReOsIrPtAuHgTlPbBiPoAtRnFrRaAcThPaUNpPuAmCmBkCfEsFmMdNoLrRfDbSgBhHsMtDsRgCnNhFlMcLvTsOg

Period 4, group 3. The other transition metals are tinted, and every cell opens its own article.

Electrons and bonding

Scandium gives up its two 4s electrons and its single 3d electron to form Sc³⁺, the only ion it commonly makes, so it behaves more like aluminum than like a typical transition metal.

Properties

State at 25 °C
solid
What it looks like
soft, silvery-white metal that yellows slightly in air
Melting point
1541 °C
Boiling point
2836 °C
Density
2.99 g/cm³

Where it is found

More common in the crust than lead, but spread so thinly that there are few ores worth mining. It is recovered mostly as a byproduct of processing other ores, in China, Russia and the Philippines.

Discovery and name

Lars Fredrik Nilson found it in 1879 in the minerals euxenite and gadolinite and named it after Scandinavia. Per Teodor Cleve soon pointed out that it was the eka-boron Mendeleev had predicted in 1871, with the atomic mass and properties he had described.

What it is used for

A little scandium makes aluminum alloys stronger for bicycle frames, baseball bats and aircraft parts. Scandium iodide goes into metal-halide lamps that light stadiums and film sets with daylight-like light, and scandium-doped zirconia is used in solid oxide fuel cells.

In compounds

Sc₂O₃scandium oxideScI₃scandium iodide, in stadium lampsScCl₃scandium chlorideScF₃scandium fluoride