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Scandium, 21Sc
Scandium
Pronunciation/ˈskændiəm/ ​(SKAN-dee-əm)
Appearancesilvery white
Standard atomic weight Ar°(Sc)
Scandium in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson
–
↑
Sc
↓
Y
calcium ← scandium → titanium
Atomic number (Z)21
Groupgroup 3
Periodperiod 4
Block  d-block
Electron configuration[Ar] 3d1 4s2
Electrons per shell2, 8, 9, 2
Physical properties
Phase at STPsolid
Melting point1814 K ​(1541 °C, ​2806 °F)
Boiling point3109 K ​(2836 °C, ​5136 °F)
Density (at 20° C)2.989 g/cm3 [3]
when liquid (at m.p.)2.80 g/cm3
Heat of fusion14.1 kJ/mol
Heat of vaporization332.7 kJ/mol
Molar heat capacity25.52 J/(mol·K)
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 1645 1804 (2006) (2266) (2613) (3101)
Atomic properties
Oxidation states0,[4] +1,[5] +2,[6] +3 (an amphoteric oxide)
ElectronegativityPauling scale: 1.36
Ionization energies
  • 1st: 633.1 kJ/mol
  • 2nd: 1235.0 kJ/mol
  • 3rd: 2388.6 kJ/mol
  • (more)
Atomic radiusempirical: 162 pm
Covalent radius170±7 pm
Van der Waals radius211 pm
Color lines in a spectral range
Spectral lines of scandium
Other properties
Natural occurrenceprimordial
Crystal structure ​hexagonal close-packed (hcp) (hP2)
Lattice constants
Hexagonal close packed crystal structure for scandium
a = 330.89 pm c = 526.80 pm (at 20 °C)[3]
Thermal expansion9.97×10−6/K (at 20 °C)[a]
Thermal conductivity15.8 W/(m⋅K)
Electrical resistivityα, poly: 562 nΩ⋅m (at r.t., calculated)
Magnetic orderingparamagnetic
Molar magnetic susceptibility+315.0×10−6 cm3/mol (292 K)[7]
Young's modulus74.4 GPa
Shear modulus29.1 GPa
Bulk modulus56.6 GPa
Poisson ratio0.279
Brinell hardness736–1200 MPa
CAS Number7440-20-2
History
Namingafter Scandinavia
PredictionDmitri Mendeleev (1871)
Discovery and first isolationLars Fredrik Nilson (1879)
Isotopes of scandium
Main isotopes[8] Decay
abun­dance half-life (t1/2) mode pro­duct
44m2Sc synth 58.61 h IT 44Sc
γ 44Sc
ε 44Ca
45Sc 100% stable
46Sc synth 83.79 d β− 46Ti
γ –
47Sc synth 80.38 h β− 47Ti
γ –
48Sc synth 43.67 h β− 48Ti
γ –
 Category: Scandium
| references

Scandium (Template:PronEng) is a chemical element with symbol Sc and atomic number 21. A silvery-white metallic transition metal, it has historically been sometimes classified as a rare earth element, together with yttrium and the lanthanides. In 1879 Lars Fredrik Nilson and his team, found a new element with spectral analysis, in the minerals euxenite and gadolinite from Scandinavia.

Scandium is present in most of the rare earth element and uranium deposits, but it is extracted from these ores in only a few mines worldwide. Due to the low availability and the difficulties in the preparation of metallic scandium, which was first done in 1937, it took until the 1970s before applications for scandium were developed. The positive effects of scandium on aluminium alloys were discovered in the 1970s, and its use in such alloys remains the only major application of scandium.

History

Dmitri Mendeleev used his periodic law, in 1869, to predict the existence of, and some properties of, three unknown elements, including one he called ekaboron. Lars Fredrik Nilson and his team, apparently unaware of that prediction in the spring of 1879, were looking for rare earth metals. By using spectral analysis, they found a new element within the minerals euxenite and gadolinite from Scandinavia.[9][10] They named it scandium, from the Latin Scandia meaning "Scandinavia". The first attempt to isolate the scandium yielded only 250 mg of impure scandium oxide, but in the second attempt, they processed 10 kilograms of euxenite, producing about 2.0 grams of a very pure scandium oxide (Sc2O3).[10]

Per Teodor Cleve of Sweden processed 10 kilograms of gadolinite to search for the new element. He concluded that scandium corresponded well to the hoped-for ekaboron, and he notified Mendeleev of this in August.[11] It took several years before William Crookes found a scandium concentration of 1% in the mineral Wiikite.[12] Fischer, Brunger, and Grieneisen prepared metallic scandium for the first time in 1937, by electrolysis of a eutectic melt of potassium, lithium, and scandium chlorides at a temperature of 700 to 800 °C. Tungsten wires in a pool of liquid zinc were the electrodes in a graphite crucible.[13] The first pound of 99% pure scandium metal was not produced until 1960. The use for aluminium alloys started after a patent was granted in 1971 in the United States. At the same time the Soviet Union also expanded the research on aluminium scandium alloys.[14]

Characteristics

Scandium is a rare, hard, silvery, rough, very dark metallic element that develops a slightly yellowish or pinkish cast when exposed to air. It is not resistant to weathering when pure and is dissolved on prolonged contact with most dilute acids. However, like some other reactive metals, this metal does not react with a 1:1 mixture of nitric acid (HNO3) and hydrofluoric acid, HF.

The rarity of scandium is not an arbitrary fact. The thermonuclear reactions that produce the elements in this range of atomic numbers tend to produce much greater quantities of elements with an even atomic number. These elements are usually produced by the fusion of lighter elements with helium-4 nuclei, starting with carbon-12 (element six). Thus, the common elements in the range of scandium are atomic numbers 18 (argon), 20 (calcium), 22 (titanium), and 24 (chromium); with elements of odd atomic numbers 19 (potassium), 21 (scandium), and 23 (vanadium) being rarely produced, and thus being much less common. The production of the odd-numbered elements in this range result from much less common thermonuclear reactions.[15]

Isotopes

Main article: isotopes of scandium

Naturally occurring scandium is composed of one stable isotope 45Sc. 13 radioisotopes have been characterized with the most stable being 46Sc with a half-life of 83.8 days, 47Sc with a half-life of 3.35 days, and 48Sc with a half-life of 43.7 hours. All of the remaining radioactive isotopes have half lives that are less than 4 hours, and the majority of these have half-lives that are less than 2 minutes. This element also has 5 meta states with the most stable being 44mSc (t½ 58.6 h).[16]

The isotopes of scandium range in atomic weight from 40 u (40Sc) to 54 u (54Sc). The primary decay mode at masses lower than the only stable isotope, 45Sc, is electron capture, and the primary mode at masses above it is beta emission. The primary decay products at atomic weights below 45Sc are calcium isotopes and the primary products from higher atomic weights are titanium isotopes.[16]

Compounds

The most common oxidation state of scandium is +3. Scandium chemically resembles yttrium and the rare earth metals more than it resembles aluminium or titanium. Thus scandium is sometimes seen as the scandium(III) oxide, Sc2O3, and as scandium(III) chloride, ScCl3. Scandium chloride dissolves in a potassium chloride solution by forming K3[ScCl6]. This shows that scandium prefers the coordination number six, similar to aluminium. In the compounds ScB and ScC, boron and carbon are incorporated non-stoichiometrically into the lattice of the scandium.[17] Alternative oxidation states of scandium are present in the hydrides scandium(II) hydride (ScH2) and scandium(I) hydride (ScH). ScH2 is stable at room temperature,[5] while ScH is only observable in high temperature gas phase spectroscopy.[6]

Occurrence

Scandium is distributed sparsely on earth, occurring only as trace quantities in many minerals. The concentration in the upper continental crust is 7ppm and 25ppm in the lower continental crust.[18] Rare minerals from Scandinavia[19] and Madagascar[20] such as thortveitite, euxenite, and gadolinite are the only known concentrated sources of this element (which is never found as a free metal). The mineral thortveititecan contains 40 - 45 % of scandium(III) oxide.[19]

It is also found in residues that remain after tungsten is extracted from wolframite, and from ores after uranium and thorium have been extracted.[21] Scandium is more common in the sun and certain stars than on Earth. Scandium is only the 50th most common element on earth (35th most abundant in the Earth's crust), but it is the 23rd most common element in the sun.[22]

Production

World production of scandium is in the order of 2,000 kg per year as scandium oxide. The primary production is 400 kg while the rest is from stockpiles of Russia created during the Cold War. The production of metallic scandium is in the order of 10 kg per year.[23][24]

In 2003 only three mines produced scandium oxide. The uranium and iron mines in Zhovti Vody in Ukraine, the rare earth mines in Bayan Obo, China and the apatite mines in the Kola peninsula, Russia, yield the scandium ore as a byproduct of mining activities for other minerals.[24] The scandium from these mines is sold as scandium oxide, and only a small fraction is converted to scandium fluoride and reduced with metallic calcium.

Madagascar and Iveland-Evje Region in Norway are the only minable deposits of minerals with high scandium content, thortveitite (Y,Sc)2(Si2O7) and kolbeckite ScPO4·2H2O.[21] Other scandium deposits are associated with uranium, nickel-copper-cobalt laterite deposits, and ultramafic rocks worldwide. The nickel and cobalt mines at Syerston and Lake Innes, New South Wales, Australia, as well as several iron, tin, and tungsten deposits in China and several uranium deposits in Russia and Kazakhstan contain scandium. Up to 2003, none of these mines was extracting the scandium from the ore residues, but projects exist for several of the mines to start scandium extraction,[24] so there is no primary production of scandium in the Americas, Europe, or Australia.

Applications

Parts of the Mig–29 are made from Al-Sc alloy.

Since it is not a very common metal, scandium does not have many applications. The main application of scandium by weight is in aluminium-scandium alloys for minor aerospace industry components. The aluminium alloys contain between 0.1% and 0.5% of scandium.[25] The Russian military aircrafts Mig 21[26] and Mig 29[25] used aluminium scandium alloys. Some unusual designs for sports equipment (bikes, golf clubs, lacrosse shafts, baseball bats,[27] firearms, etc.) which rely on high performance materials also use scandium to improve the properties of aluminium. However, titanium, being much more common, and similar in lightness and strength, is much more widely used, with tons found in some aircraft, especially military ones. When added to aluminium, scandium substantially lowers the rate of recrystallization and associated grain-growth in weld heat-affected zones. Aluminium, being a face-centred cubic metal, is not particularly subject to the strengthening effects of the decrease in grain diameter. However, the presence of fine dispersions of Al3Sc does increase strength by a small measure, much as any other precipitate system in aluminium alloys. It is added to aluminium alloys primarily to control otherwise excessive grain growth in the heat-affected zone of weldable structural aluminium alloys, which gives two knock-on effects; greater strengthening via finer precipitation of other alloying elements and by reducing the precipitate-free zones that normally exist at the grain boundaries of age-hardening aluminium alloys.[25]

It is used in lacrosse sticks and baseball bats; a light yet strong metal is needed for precise accuracy and speed. Backcountry tent manufacturers sometimes use scandium alloys in tent poles. U.S. gunmaker Smith & Wesson produces a few variations including a large, medium, and small lightweight revolver with a frame composed of scandium alloy and a titanium cylinder.[28]

Approximately 20 kg (as Sc2O3) of scandium is used annually in the United States to make high-intensity lights.[29] Scandium iodide added to mercury-vapor lamps produces an efficient artificial light source that resembles sunlight, and which allows good color-reproduction with TV cameras.[30] About 80 kg of scandium is used in light bulbs globally per year. The radioactive isotope Sc-46 is used in oil refineries as a tracing agent.[29]

The original use of scandium-aluminium alloys was in the nose cones of some USSR submarine-launched ballistic missiles (SLBMs). The strength of the resulting nose cone was enough to enable it to pierce the ice-cap without damage, and so enable a missile launch while still submerged under the Arctic ice cap.[citation needed]

Scandium triflate is a catalytic Lewis acid used in organic chemistry.[31]

Contrary to a misconception, the blue color of the aquamarine variety of beryl is not caused by scandium impurities.[32] Rather, the color centers of the aquamarine are due to iron(III) and iron(II) ions incorporated into the beryl structure.[33]

Precautions

The pure metal is not considered toxic, but scandium compounds should be handled as if they are toxic because the ionic forms of metals are normally at greatest risk for toxicity, and limited animal testing has been done for scandium compounds.[34] The LD50 levels for scandium(III) chloride for rats have been determined and were intraperitoneal 4 mg/kg and oral 755 mg/kg.[35]

See also

References

  1. ^ "Standard Atomic Weights: Scandium". CIAAW. 2021.
  2. ^ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
  3. ^ a b Arblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN 978-1-62708-155-9.
  4. ^ Cloke, F. Geoffrey N.; Khan, Karl & Perutz, Robin N. (1991). "η-Arene complexes of scandium(0) and scandium(II)". J. Chem. Soc., Chem. Commun. (19): 1372–1373. doi:10.1039/C39910001372.
  5. ^ a b Smith, R. E. (1973). "Diatomic Hydride and Deuteride Spectra of the Second Row Transition Metals". Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences. 332 (1588): 113–127. Bibcode:1973RSPSA.332..113S. doi:10.1098/rspa.1973.0015. S2CID 96908213.
  6. ^ a b McGuire, Joseph C.; Kempter, Charles P. (1960). "Preparation and Properties of Scandium Dihydride". Journal of Chemical Physics. 33 (5): 1584–1585. Bibcode:1960JChPh..33.1584M. doi:10.1063/1.1731452.
  7. ^ Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.
  8. ^ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
  9. ^ Lars Fredrik Nilson (1879). "Sur l'ytterbine, terre nouvelle de M. Marignac". Comptes Rendus. 88: 642–647.
  10. ^ a b F. L. Nilson (1879). "Ueber Scandium, ein neues Erdmetall". Berichte der deutschen chemischen Gesellschaft. 12 (1): 554–557. doi:10.1002/cber.187901201157.
  11. ^ Per Teodor Cleve (1879). "Sur le scandium". Comptes Rendus. 89: 419–422.
  12. ^ William Crookes (1909). "On Scandium". Philosophical Transactions of the Royal Society of London. Series A. 209: 15–46.
  13. ^ Fischer, Werner (1937). "Über das metallische Scandium". Zeitschrift für anorganische und allgemeine Chemie. 231 (1–2): 54–62. doi:10.1002/zaac.19372310107. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  14. ^ Zakharov, V. V. (2003). "Effect of Scandium on the Structure and Properties of Aluminum Alloys". Metal Science and Heat Treatment. 45 (7–8): 246–253. doi:10.1023/A:1027368032062.
  15. ^ Clayton, Donald D. (2003). Handbook of Isotopes in the Cosmos. Cambridge University Press. pp. 199–201. ISBN 9780521823814.
  16. ^ a b Audi, Georges (2003). "The NUBASE Evaluation of Nuclear and Decay Properties". Nuclear Physics A. 729. Atomic Mass Data Center: 3–128. doi:10.1016/j.nuclphysa.2003.11.001.
  17. ^ Holleman, Arnold F. (1985). Lehrbuch der Anorganischen Chemie (91–100 ed.). Walter de Gruyter. pp. 1055&ndas, 1056. ISBN 3110075113. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  18. ^ Bernhard, F. (2001). "Scandium mineralization associated with hydrothermal lazurite-quartz veins in the Lower Austroalpie Grobgneis complex, East Alps, Austria". Mineral Deposits in the Beginning of the 21st Century. ISBN 9026518463.
  19. ^ a b Kristiansen, Roy (2003). "Scandium - Mineraler I Norge" (PDF). Stein (in Norwegian): 14–23.
  20. ^ von Knorring, O. (1987). "Mineralized pegmatites in Africa". Geological Journal. 22: 253–-270. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  21. ^ a b "Mineral Commodity Summaries 2008: Scandium" (PDF). United States Geological Survey. Retrieved 2008-10-20.
  22. ^ CRC Handbook of Chemistry and Physics. 2004. ISBN 9780849304859. {{cite book}}: |first= missing |last= (help); Text "CRC Press" ignored (help)
  23. ^ Hedrick, James B. "Commodity Report: Scandium 2006" (PDF). United States Geological Survey. Retrieved 2008-09-20.
  24. ^ a b c Deschamps, Y. "Scandium" (PDF). mineralinfo.com. Retrieved 2008-10-21.
  25. ^ a b c Ahmad, Zaki (2003). "The properties and application of scandium-reinforced aluminum". JOM Journal of the Minerals, Metals and Materials Society. 55 (2): 35–39. doi:10.1007/s11837-003-0224-6.
  26. ^ Fuller. "Temporal Evolution of the Microstructures of Al(Sc,Zr) Alloys and Their Influences on Mechanical Properties" (PDF). Northwestern University. {{cite web}}: Text "accessdate 2008-10-21" ignored (help); Text "first C." ignored (help)
  27. ^ Bjerklie, Steve (2006). "A batty business: Anodized metal bats have revolutionized baseball. But are finishers losing the sweet spot?". Metal Finishing. 104 (4): 61–62. doi:10.1016/S0026-0576(06)80099-1.
  28. ^ "Small Frame (J) - Model 340PD Revolver". Smith & Wesson. Retrieved 2008-10-20.
  29. ^ a b C.R. Hammond in CRC Handbook of Chemistry and Physics 85th ed., Section 4; The Elements
  30. ^ Simpson, Robert S. (2003). Lighting Control: Technology and Applications. Focal Press. p. 108. ISBN 9780240515663.
  31. ^ Kobayashi, Shu (2000). "Green Lewis acid catalysis in organic synthesis" (PDF). Pure Appl. Chem. 72 (7): 1373–1380. doi:10.1351/pac200072071373. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  32. ^ Bottrill, R. S. "Rare earth, tantalum and niobium minerals reported in Tasmania" (PDF). Retrieved 2008-10-20. {{cite web}}: Unknown parameter |published= ignored (help)
  33. ^ Viana, R. R. (2002). "Characterization of beryl (aquamarine variety) from pegmatites of Minas Gerais, Brazil". Physics and Chemistry of Minerals. 29 (10): 668–679. doi:10.1007/s00269-002-0278-y. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)CS1 maint: extra punctuation (link)
  34. ^ Horovitz, Chaim T. (1999). Biochemistry of Scandium and Yttrium. Springer. ISBN 9780306456572. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  35. ^ Haley, Thomas J. "Pharmacology and toxicology of scandium chloride". Journal of Pharmaceutical Sciences. 51 (11): 1043–1045. doi:10.1002/jps.2600511107. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

External links

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