Scandium

Scandium,  ₂₁Sc

General properties
Name, symbol	Scandium, Sc
Appearance	Silvery-white metal
Scandium in the periodic table
- ↑ Sc ↓ Y Calcium ← Scandium → Titanium
Atomic number	21
Standard atomic weight (Ar)	44.955908(5)
Group, block	, d-block
Period	period 4
Electron configuration	[Ar] 3d1 4s2
per shell	2, 8, 9, 2
Physical properties
Silvery-white
Phase	Solid
Melting point	1814 K ​(1541 °C, ​​2806 °F)
Boiling point	3109 K ​(2836 °C, ​5136 °F)
Density near r.t.	2.985 g/cm3
when liquid, at	2.80 g/cm3
Heat of fusion	14.1 kJ/mol
Heat of	332.7 kJ/mol
Molar heat capacity	25.52 J/(mol·K)
pressure
Atomic properties
Oxidation states	3, 2, 1 ​(an amphoteric oxide)
Electronegativity	Pauling scale: 1.36
energies	1st: 633.1 kJ/mol 2nd: 1235.0 kJ/mol 3rd: 2388.6 kJ/mol (more)
Atomic radius	empirical: 162 pm
Covalent radius	170±7 pm
Van der Waals radius	211 pm
Miscellanea
Crystal structure	​​hexagonal close-packed (hcp)
Thermal expansion	α, poly: 10.2 µm/(m·K) (at r.t.)
Thermal conductivity	15.8 W/(m·K)
Electrical resistivity	α, poly: 562 Ω·m (at r.t., calculated)
Magnetic ordering	Paramagnetic
Young's modulus	74.4 GPa
Shear modulus	29.1 GPa
Bulk modulus	56.6 GPa
Poisson ratio	0.279
Brinell hardness	736–1200 MPa
CAS Registry Number	7440-20-2
History
Naming	after Scandinavia
Prediction	Dmitri Mendeleev (1871)
Discovery and first isolation	Lars Fredrik Nilson (1879)

Scandium is a chemical element with symbol Sc and atomic number 21. Scandium is classified as a rare earth element, together with yttrium and the lanthanides, due to their similar chemical properties. It is a hard to find element, mainly due to the lack of concentrated ores, with a global production of 10 tonnes per year.

Properties

Chemical

Scandium reacts slowly with most acids, though it resists a 1:1 mixture of nitric acid and hydrofluoric acid, mainly due to the formation of a passivation layer.

Scandium powder and turnings ignite in air with a brilliant yellow flame to form scandium(III) oxide (also known as scandia).

4 Sc + 3 O₂ → 2 Sc₂O₃

Physical

Scandium is a silvery-white metal, which slowly oxidizes in air, developing a slight yellow or pinkish cast due to the formation of an oxide layer.

Availability

Scandium metal is sold by various chemicals suppliers, though it's quite expensive. Metallium sells a 5 gram sample at $ 97.

Isolation

Scandium can be extracted by reducing scandium(III) oxide with a more reactive metal, such as calcium. Replacing scandia with scandium(III) fluoride gives the process a better yield.

Another method involves the electrolysis of an eutectic mixture of potassium, lithium, and scandium chlorides, at 700–800 °C. This was the first method used to obtain pure scandium metal.

Projects

• Yellow flame
• Make scandium(III) fluoride, an interesting compound which displays negative thermal expansion (shrinks when heated)
• Element collecting

Handling

Safety

Elemental scandium is considered non-toxic, though its compounds display moderate toxicity.

Storage

Scandium should be stored in sealed containers or ampoules, away from air, moisture and corrosive vapors.

Disposal

Due to it's rarity, it's best to try and recycle scandium, instead of throwing it away.

References

Relevant Sciencemadness threads

• Scandium: why only 3+?