Difference between revisions of "Scandium"
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*Yellow flame | *Yellow flame | ||
*Make [[scandium(III) fluoride]], an interesting compound which displays negative thermal expansion (shrinks when heated) | *Make [[scandium(III) fluoride]], an interesting compound which displays negative thermal expansion (shrinks when heated) | ||
| − | * | + | *[[Element collecting]] |
==Handling== | ==Handling== | ||
Latest revision as of 17:59, 18 July 2019
| General properties | |||||
|---|---|---|---|---|---|
| Name, symbol | Scandium, Sc | ||||
| Appearance | Silvery-white metal | ||||
| Scandium in the periodic table | |||||
| |||||
| 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.
Contents
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.
