Scandium

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Scandium,  21Sc
General properties
Name, symbol Scandium, Sc
Appearance Silvery-white metal
Scandium in the periodic table
-

Sc

Y
CalciumScandiumTitanium
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)
· references

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)
  • Ellement 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