Difference between revisions of "Scandium" - New World Encyclopedia

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{{Elementbox_header | number=21 | symbol=Sc | name=scandium | left=[[calcium]] | right=[[titanium]] | above=- | below=[[yttrium|Y]] | color1=#ffc0c0 | color2=black }}
 
{{Elementbox_header | number=21 | symbol=Sc | name=scandium | left=[[calcium]] | right=[[titanium]] | above=- | below=[[yttrium|Y]] | color1=#ffc0c0 | color2=black }}
 
{{Elementbox_series | [[transition metal]]s }}
 
{{Elementbox_series | [[transition metal]]s }}
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{{Elementbox_brinellhardness_mpa | 750 }}
 
{{Elementbox_brinellhardness_mpa | 750 }}
 
{{Elementbox_cas_number | 7440-20-2 }}
 
{{Elementbox_cas_number | 7440-20-2 }}
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{{Elementbox_isotopes_begin | color1=#ffc0c0 | color2=black }}
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{{Elementbox_isotopes_begin | isotopesof=scandium| color1=#ffc0c0 | color2=black }}
 
{{Elementbox_isotopes_decay3 | mn=44[[Nuclear isomer|m]] | sym=Sc | na=[[synthetic radioisotope|syn]] | hl=[[1 E5 s|58.61 h]] | dm1=[[Internal conversion|IT]] | de1=0.2709 | pn1=44 | ps1=Sc |
 
{{Elementbox_isotopes_decay3 | mn=44[[Nuclear isomer|m]] | sym=Sc | na=[[synthetic radioisotope|syn]] | hl=[[1 E5 s|58.61 h]] | dm1=[[Internal conversion|IT]] | de1=0.2709 | pn1=44 | ps1=Sc |
 
dm2=[[gamma ray|γ]] | de2=1.0, 1.1, 1.1 | pn2= | ps2=- |
 
dm2=[[gamma ray|γ]] | de2=1.0, 1.1, 1.1 | pn2= | ps2=- |
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dm2=[[gamma ray|γ]] | de2=0.889, 1.120 | pn2= | ps2=- }}
 
dm2=[[gamma ray|γ]] | de2=0.889, 1.120 | pn2= | ps2=- }}
 
{{Elementbox_isotopes_decay2 | mn=47 | sym=Sc | na=[[synthetic radioisotope|syn]] | hl=[[1 E5 s|3.3492 d]] | dm1=[[beta emission|β<sup>-</sup>]] | de1=0.44, 0.60 | pn1=47 | ps1=[[titanium|Ti]] |
 
{{Elementbox_isotopes_decay2 | mn=47 | sym=Sc | na=[[synthetic radioisotope|syn]] | hl=[[1 E5 s|3.3492 d]] | dm1=[[beta emission|β<sup>-</sup>]] | de1=0.44, 0.60 | pn1=47 | ps1=[[titanium|Ti]] |
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dm2=[[gamma ray|γ]] | de2=0.159 | pn2= | ps2=- }}
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dm2=[[gamma ray|γ]] | de2=0.159 | pn2= | ps2=- }}
 
{{Elementbox_isotopes_decay2 | mn=48 | sym=Sc | na=[[synthetic radioisotope|syn]] | hl=[[1 E5 s|43.67 h]] | dm1=[[beta emission|β<sup>-</sup>]] | de1=0.661 | pn1=48 | ps1=[[titanium|Ti]] |
 
{{Elementbox_isotopes_decay2 | mn=48 | sym=Sc | na=[[synthetic radioisotope|syn]] | hl=[[1 E5 s|43.67 h]] | dm1=[[beta emission|β<sup>-</sup>]] | de1=0.661 | pn1=48 | ps1=[[titanium|Ti]] |
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dm2=[[gamma ray|γ]] | de2=0.9, 1.3, 1.0 | pn2= | ps2=- }}
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dm2=[[gamma ray|γ]] | de2=0.9, 1.3, 1.0 | pn2= | ps2=- }}
 
{{Elementbox_isotopes_end}}
 
{{Elementbox_isotopes_end}}
 
{{Elementbox_footer | color1=#ffc0c0 | color2=black }}
 
{{Elementbox_footer | color1=#ffc0c0 | color2=black }}
  
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'''Scandium''' (chemical symbol '''Sc''', [[atomic number]] 21) is a soft, silvery, white [[metal]]. Scandium ore occurs in rare minerals from [[Scandinavia]] and elsewhere. It is sometimes considered along with [[yttrium]] and the [[lanthanide]]s and [[actinides]], to be a [[rare earth]].
+
'''Scandium''' (chemical symbol '''Sc''', [[atomic number]] 21) is a soft, silvery-white [[metal]]. Scandium ore occurs in rare [[mineral]]s from [[Scandinavia]] and elsewhere. It is a rare element that chemically resembles yttrium and is sometimes considered a [[rare earth]], along with [[yttrium]], the [[lanthanide]]s, and [[actinide]]s.
 +
{{toc}}
 +
This element is mainly used in [[alloy]]s with [[aluminum]] for minor components needed by the aerospace industry and for high-performance sports equipment, including bicycles, baseball bats, and firearms. Scandium oxide is used to make high-intensity lights, and scandium iodide is used in mercury-vapor lamps. A radioactive [[isotope]] of scandium [Sc-46] is used as a tracing agent in [[oil refinery|oil refineries]].
  
−
== Occurrence ==
+
== Occurrence and isolation ==
−
Scandium is distributed sparsely on earth, occurring only as trace quantities in many [[mineral]]s. Rare minerals from Scandinavia and [[Madagascar]], such as [[thortveitite]], [[euxenite]], and [[gadolinite]] are the only known concentrated sources of this element (which is never found as a free metal). It is also found in residues that remain after [[tungsten]] is extracted from [[wolframite]], and from ores after [[uranium]] and [[thorium]] have been extracted.
 
  
−
Scandium is more common in the sun and certain [[star]]s than on [[Earth]]. Scandium is only the 50th most common element on earth (35th most abundant in the Earth's [[Crust (geology)|crust]]), but it is the 23rd most common element in the sun.
+
Scandium is distributed sparsely on [[Earth]], occurring only as trace quantities in various [[mineral]]s. It is never found as a free metal. Rare minerals from [[Scandinavia]] and [[Madagascar]]&mdash;such as [[thortveitite]], [[euxenite]], and [[gadolinite]]&mdash;are the only known concentrated sources of this element. It is also found in residues that remain after [[tungsten]] is extracted from [[wolframite]], and in the byproducts of [[uranium]]-mill tailings.
 +
 
 +
Scandium is more common in the [[Sun]] and certain [[star]]s than on [[Earth]]. It is only the fiftieth most common element on Earth (thirty-fifth most abundant in the Earth's crust), but it is the twenty-third most common element in the Sun.
 
 
 
 
−
The [[blue]] color of the [[aquamarine]] variety of [[beryl]] is thought to be caused by scandium impurities in it.
+
The [[blue]] color of the [[aquamarine]] variety of [[beryl]] is thought to be produced by the presence of scandium impurities in it.
−
 
 
−
== Isolation ==
 
−
 
 
−
Thortveitite is the primary source of scandium. [[Uranium]]-mill tailings by-products also are an important source. Pure scandium is commercially produced by [[redox|reducing]] [[Scandium(III) fluoride|scandium fluoride]] with metallic [[calcium]].
 
 
 
 
 
−
The present main source of scandium metal is from the military stockpiles of the former Soviet Union (mainly in the country of [[Ukraine]]), which were themselves extracted from uranium tailings. There is no primary production in the Americas, Europe, or Australia.
+
The present main source of scandium metal is from military stockpiles in parts of the former [[Soviet Union]] (mainly in [[Ukraine]]), which were themselves obtained from [[uranium]] tailings. There is no primary production in the Americas, Europe, or Australia.
  
 
== History ==
 
== 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 ''[[Mendeleev's predicted elements#Ekaboron and scandium|ekaboron]]''.
+
In 1869, [[Dmitri Mendeleev]] used his [[periodic law]] to predict the existence and some properties of three unknown elements, including one that he called ''[[Mendeleev's predicted elements#Ekaboron and scandium|ekaboron]]''.
 
 
 
 
−
[[Lars Fredrick 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 [[discovery of the chemical elements|found a new element]] within the minerals [[euxenite]] and [[gadolinite]]. They named it scandium, from the [[Latin]] ''Scandia'' meaning "Scandinavia", and in the process of isolating the scandium, they processed 10 [[kilogram]]s of euxenite, producing about 2.0 [[gram]]s of a very pure [[scandia|scandium oxide]]* (Sc<sub>2</sub>O<sub>3</sub>).
+
Apparently unaware of that prediction, [[Lars Fredrick Nilson]] and his team were looking for [[rare earth]] metals in the spring of 1879. Using spectral analysis, they [[discovery of the chemical elements|found a new element]] in the minerals [[euxenite]] and [[gadolinite]]. They named it scandium, from the [[Latin]] word ''Scandia'' meaning "Scandinavia." In attempting to isolate scandium, they processed ten kilograms of euxenite and produced about two [[gram]]s of a very pure [[scandia|scandium oxide]] (Sc<sub>2</sub>O<sub>3</sub>).
 
 
 
 
−
[[Per Teodor Cleve]]* of Sweden concluded that scandium corresponded well to the hoped-for ekaboron, and he notified Mendeleev of this in August.
+
[[Per Teodor Cleve]] of Sweden concluded that scandium corresponded well to the hoped-for ekaboron, and he notified Mendeleev of this in August.
 
 
 
 
−
Fischer, Brunger, and Grienelaus prepared metallic scandium for the first time in 1937, by [[electrolysis]] of a [[eutectic]] melt of [[potassium]], [[lithium]], and [[scandium chloride]]*s at a temperature of 700 to 800°[[Celsius|C]]. [[Tungsten]] wires in a pool of liquid [[zinc]] were the [[electrode]]s in a [[graphite]] crucible. The first pound of 99% pure scandium metal was not produced until 1960.
+
Fischer, Brunger, and Grienelaus prepared metallic scandium for the first time in 1937. They performed [[electrolysis]] of a molten combination of [[potassium]], [[lithium]], and scandium chlorides, at a temperature of 700 to 800°C. [[Tungsten]] wires in a pool of liquid [[zinc]] were the [[electrode]]s in a [[graphite]] crucible. The first pound of 99 percent pure scandium metal was not produced until 1960.
 
 
 
 
 
== Notable characteristics ==
 
== Notable characteristics ==
  
−
Scandium is a rare, soft, silvery, very light [[metal]]lic element that develops a slightly yellowish or pinkish cast when exposed to air. This metal is not attacked by a 1:1 mixture of [[nitric acid]]([[hydrogen|H]][[nitrogen|N]][[oxygen|O]]<sub>3</sub>) and hydrofluoric acid, [[hydrogen|H]][[fluorine|F]].
+
Scandium is situated between [[calcium]] and [[titanium]] in period four of the [[periodic table]]. It is the first [[transition metal]] in period four. In addition, it lies at the top of group three (former group 3B), just above [[yttrium]]. Chemically, it resembles yttrium (and the rare earth metals) more than it resembles [[titanium]].
−
The rarity of scandium is not an arbitrary fact. In this area of [[atomic number]]s, the thermonuclear reactions that produced the elements, very much more commonly produces elements with an even atomic number. This is because these elements were 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 number 18 [[argon]], number 20 [[calcium]], number 22 [[titanium]], number 24 [[chromium]]; with the odd-numbered elements 19 [[potassium]], 21 scandium, and 23 [[vanadium]] being rarely produced, and much less common. The production of the odd-numbered elements in this range results from much-less common thermonuclear reactions, as is explained elsewhere.
+
 
 +
Silvery when pure, scandium develops a slightly yellowish or pinkish cast when exposed to air. It is a soft, light metal. It is resistant to corrosion by [[acid]]s. For example, it is not attacked by a 1:1 mixture of [[nitric acid]]([[hydrogen|H]][[nitrogen|N]][[oxygen|O]]<sub>3</sub>) and hydrofluoric acid (H[[fluorine|F]]).
 +
 
 +
When added to weldable structural aluminum alloys, scandium strengthens the alloys by lowering the rate of recrystallization and associated grain growth in the heat-affected zones.
 +
 
 +
In most of its compounds, the [[oxidation state]] of scandium is +3. Thus scandium is sometimes seen as the oxide, Sc<sub>2</sub>0<sub>3</sub>, or the chloride, ScCl<sub>3</sub>.
  
 
=== Isotopes ===
 
=== Isotopes ===
  
−
Naturally occurring scandium is composed of 1 stable [[isotope]] <sup>45</sup>Sc. 13 [[radioisotope]]s have been characterized with the most stable being <sup>46</sup>Sc with a [[half-life]] of 83.8 days, <sup>47</sup>Sc with a half-life of 3.35 days, and <sup>48</sup>Sc with a half-life of 43.7 hours. All of the remaining [[radioactive]] isotopes have half-lifes that are less than 4 hours, and the majority of these have half-lifes that are less than 2 minutes. This element also has 5 [[meta state]]s with the most stable being <sup>44m</sup>Sc (t<sub>½</sub> 58.6 h).
+
Naturally occurring scandium is composed of one stable [[isotope]], <sup>45</sup>Sc. In addition, many [[radioactive]] isotopes have been produced artificially, with atomic mass numbers ranging from 36 to 60. The three most stable radioisotopes are: <sup>46</sup>Sc, with a [[half-life]] of 83.8 days; <sup>47</sup>Sc, with a half-life of 3.35 days; and <sup>48</sup>Sc, with a half-life of 43.7 hours. The remaining radioactive isotopes have half-lives that are less than four hours, and the majority of these have half-lives that are less than two minutes.
  
−
The isotopes of scandium range in [[atomic weight]] from 40 [[atomic mass unit|amu]] (<sup>40</sup>Sc) to 54 amu (<sup>54</sup>Sc). The primary [[decay mode]] at masses lower than the only stable isotope, <sup>45</sup>Sc, is [[electron capture]], and the primary mode at masses above it is [[beta emission]]. The primary [[decay product]]s at atomic weights below <sup>45</sup>Sc are [[calcium]] isotopes and the primary products from higher atomic weights are [[titanium]] isotopes.
+
== Compounds ==
  
−
== Compounds ==
+
* ''Scandium(III) chloride'', ''scandium chloride'', or ''scandium trichloride'' (ScCl<sub>3</sub>): The pure compound is a white crystalline solid that is [[hygroscopic]] (absorbs moisture from the air). It is an [[ionic compound]] with a high [[melting point]] (960 °C). It is primarily of interest in the research laboratory. At high temperatures, it reacts with scandium metal to produce a broad family of scandium chlorides, including Sc<sub>5</sub>Cl<sub>8</sub> and Sc<sub>7</sub>Cl<sub>12</sub>. Scandium(III) chloride is used in [[metal halide lamp|halide lamps]], [[optical fiber]]s, electronic ceramics, and [[lasers]].
−
The most common [[oxidation state]] of scandium in [[:Category:Scandium compounds|compounds]] 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 oxide, (Sc2)(03), and as scandium chloride, Sc(Cl)3.
 
  
−
* See also [[:Category:Scandium compounds|Scandium compounds]].
+
* ''Scandium(III) oxide'', ''scandium oxide'', or ''scandia'' (Sc<sub>2</sub>O<sub>3</sub>): This [[amorphous]], white powder is an [[ionic compound]]. Given its resistance to heat and thermal shock, it is used in high-temperature systems. In addition, it is used in electronic ceramics and glass composition (as a helper material). The oxide will dissolve in [[alkali]] to form scandate salts. In this respect, it is more similar to [[aluminum oxide]] than to [[yttrium oxide]] or [[lanthanum oxide]].  
  
 
== Applications ==
 
== Applications ==
  
−
Since it is a very rare metal, scandium doesn't have many applications. If it were more common, it might be useful in the making of aircraft and spacecraft structures, probably alloyed with other metals.
+
As a very rare metal, scandium has a limited number of applications, some of which are noted below.
  
−
It is also used in various lacrosse sticks. The light yet strong metal is need for precise accuracy and speed.
+
* The main application of scandium by weight is in aluminum-scandium [[alloy]]s for minor aerospace industry components and for sports equipment&mdash;such as specially designed [[bike]]s, [[baseball]] bats, [[lacrosse]] sticks, and firearms&mdash;requiring strong, lightweight, high-performance materials. Yet [[titanium]], being much more readily available and similar in lightness and strength, is more widely used, with tons of it used in some military aircraft.
  
−
Approximately 20 kg (as Sc<sub>2</sub>[[oxygen|O]]<sub>3</sub>) of scandium is used annually in the [[United States]] to make high-intensity lights. <ref name="CRC">C.R. Hammond in ''CRC Handbook of Chemistry and Physics'' 85th ed., Section 4; The Elements</ref> Scandium iodide added to [[mercury-vapor lamp]]s produces an efficient artificial light source that resembles sunlight, and which allows good color-reproduction with [[television|TV]] cameras. About 80 kg of scandium is used in light bulbs globally per year. The [[radioactive isotope]] Sc-46 is used in [[oil refinery|oil refineries]] as a tracing agent. <ref name="CRC"/>
+
* Approximately 20 kilograms (kg) of scandium (as Sc<sub>2</sub>O<sub>3</sub>) is used annually in the [[United States]] to make high-intensity lights.<ref name="CRC">C.R. Hammond. ''CRC Handbook of Chemistry and Physics'', 85th ed., Section 4; The Elements.</ref>
  
−
The main application of scandium by weight is in aluminium-scandium [[alloy]]s for minor aerospace industry components, and for unusual designs sports equipment (bikes, baseball bats, firearms, etc.) which rely on high performance materials. 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.  
+
* Scandium iodide added to [[mercury-vapor lamp]]s produces an efficient artificial light source that resembles sunlight and allows good color-reproduction with [[television]] cameras.
  
−
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 Al<sub>3</sub>Sc does increase strength by a small measure, much as any other precipitate system in aluminium alloys. It is added to aluminum alloys primarily to control that 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.
+
* About 80 kg of scandium is used in light bulbs globally per year.
  
−
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, enabling a missile launch while still submerged under the Arctic ice cap.
+
* The radioactive isotope Sc-46 is used in [[oil refinery|oil refineries]] as a tracing agent.<ref name="CRC"/>
 +
 
 +
* Earlier, scandium-aluminum alloys were used in the nose cones of some Soviet submarine-launched ballistic missiles (SLBMs). The resulting nose cone was sufficiently strong to enable it to pierce the ice cap without damage, thus enabling a missile launch from a submarine under the Arctic ice cap.
  
 
== See also ==
 
== See also ==
−
* [[:Category:Scandium compounds|Scandium compounds]]
+
 
−
* [[:Category:Scandium minerals|Scandium minerals]]
+
* [[Chemical element]]
 +
* [[Metal]]
 +
* [[Periodic table]]
 +
* [[Transition metal]]
  
 
== Footnotes ==
 
== Footnotes ==
Line 114: Line 123:
 
==References==
 
==References==
  
−
* Cotton, F. Albert; and Wilkinson, Geoffrey (1980), ''Advanced Inorganic Chemistry'' (4th ed.), New York: Wiley. ISBN 0-471-02775-8.
+
* Cotton, F. Albert and Wilkinson, Geoffrey. 1980. ''Advanced Inorganic Chemistry'', 4th ed. New York: Wiley. ISBN 0-471-02775-8
−
* [http://periodic.lanl.gov/elements/21.html Scandium] Los Alamos National Laboratory. Accessed on November 29, 2006.
+
* Greenwood, N.N. and Earnshaw, A. 1998. ''Chemistry of the Elements'', 2nd Edition. New York: Elsevier. ISBN 0750633654
−
* [http://www.speclab.com/elements/scandium.htm Scandium] SPECTRUM Chemical Fact Sheet. Accessed on November 29, 2006.
+
* [http://periodic.lanl.gov/elements/21.html Scandium] Los Alamos National Laboratory. Retrieved December 9, 2007.
 +
* [http://www.speclab.com/elements/scandium.htm Scandium] SPECTRUM Chemical Fact Sheet. Retrieved December 9, 2007.
 +
* Stwertka, Albert. 2002. ''A Guide to the Elements'', 2nd ed. Oxford: Oxford University Press. ISBN 0195150279
  
 
== External links ==
 
== External links ==
−
*[http://www.webelements.com/webelements/elements/text/Sc/index.html WebElements.com &ndash; Scandium]
+
All links retrieved January 25, 2023. 
 +
*[http://www.webelements.com/webelements/elements/text/Sc/index.html Scandium] WebElements.com.
  
 
[[Category:Physical sciences]]
 
[[Category:Physical sciences]]
 
[[Category:Chemistry]]
 
[[Category:Chemistry]]
 +
[[Category:Earth sciences]]
  
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{{credit|89971337}}
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{{credit3|Scandium|89971337|Scandium(III)_chloride|89104388|Scandium(III)_oxide|89334164}}

Latest revision as of 17:06, 25 January 2023


21 calcium ← scandium → titanium
-
↑
Sc
↓
Y
Sc-TableImage.png
periodic table
General
Name, Symbol, Number scandium, Sc, 21
Chemical series transition metals
Group, Period, Block 3, 4, d
Appearance silvery white
Sc,21.jpg
Atomic mass 44.955912(6) g/mol
Electron configuration [Ar] 3d1 4s2
Electrons per shell 2, 8, 9, 2
Physical properties
Phase solid
Density (near r.t.) 2.985 g/cm³
Liquid density at m.p. 2.80 g/cm³
Melting point 1814 K
(1541 °C, 2806 °F)
Boiling point 3109 K
(2836 °C, 5136 °F)
Heat of fusion 14.1 kJ/mol
Heat of vaporization 332.7 kJ/mol
Heat capacity (25 °C) 25.52 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
Crystal structure hexagonal
Oxidation states 3
(weakly basic oxide)
Electronegativity 1.36 (Pauling scale)
Ionization energies
(more) 		1st: 633.1 kJ/mol
2nd: 1235.0 kJ/mol
3rd: 2388.6 kJ/mol
Atomic radius 160 pm
Atomic radius (calc.) 184 pm
Covalent radius 144 pm
Miscellaneous
Magnetic ordering ???
Electrical resistivity (r.t.) (α, poly)
calc. 562 nΩ·m
Thermal conductivity (300 K) 15.8 W/(m·K)
Thermal expansion (r.t.) (α, poly)
10.2 µm/(m·K)
Speed of sound (thin rod) (r.t.) 74.4 m/s
Shear modulus 29.1 GPa
Bulk modulus 56.6 GPa
Poisson ratio 0.279
Brinell hardness 750 MPa
CAS registry number 7440-20-2
Notable isotopes
Main article: Isotopes of scandium
iso NA half-life DM DE (MeV) DP
44mSc syn 58.61 h IT 0.2709 44Sc
γ 1.0, 1.1, 1.1 -
ε - 44Ca
45Sc 100% Sc is stable with 24 neutrons
46Sc syn 83.79 d β- 0.3569 46Ti
γ 0.889, 1.120 -
47Sc syn 3.3492 d β- 0.44, 0.60 47Ti
γ 0.159 -
48Sc syn 43.67 h β- 0.661 48Ti
γ 0.9, 1.3, 1.0 -

Scandium (chemical symbol Sc, atomic number 21) is a soft, silvery-white metal. Scandium ore occurs in rare minerals from Scandinavia and elsewhere. It is a rare element that chemically resembles yttrium and is sometimes considered a rare earth, along with yttrium, the lanthanides, and actinides.

This element is mainly used in alloys with aluminum for minor components needed by the aerospace industry and for high-performance sports equipment, including bicycles, baseball bats, and firearms. Scandium oxide is used to make high-intensity lights, and scandium iodide is used in mercury-vapor lamps. A radioactive isotope of scandium [Sc-46] is used as a tracing agent in oil refineries.

Occurrence and isolation

Scandium is distributed sparsely on Earth, occurring only as trace quantities in various minerals. It is never found as a free metal. Rare minerals from Scandinavia and Madagascar—such as thortveitite, euxenite, and gadolinite—are the only known concentrated sources of this element. It is also found in residues that remain after tungsten is extracted from wolframite, and in the byproducts of uranium-mill tailings.

Scandium is more common in the Sun and certain stars than on Earth. It is only the fiftieth most common element on Earth (thirty-fifth most abundant in the Earth's crust), but it is the twenty-third most common element in the Sun.

The blue color of the aquamarine variety of beryl is thought to be produced by the presence of scandium impurities in it.

The present main source of scandium metal is from military stockpiles in parts of the former Soviet Union (mainly in Ukraine), which were themselves obtained from uranium tailings. There is no primary production in the Americas, Europe, or Australia.

History

In 1869, Dmitri Mendeleev used his periodic law to predict the existence and some properties of three unknown elements, including one that he called ekaboron.

Apparently unaware of that prediction, Lars Fredrick Nilson and his team were looking for rare earth metals in the spring of 1879. Using spectral analysis, they found a new element in the minerals euxenite and gadolinite. They named it scandium, from the Latin word Scandia meaning "Scandinavia." In attempting to isolate scandium, they processed ten kilograms of euxenite and produced about two grams of a very pure scandium oxide (Sc2O3).

Per Teodor Cleve of Sweden concluded that scandium corresponded well to the hoped-for ekaboron, and he notified Mendeleev of this in August.

Fischer, Brunger, and Grienelaus prepared metallic scandium for the first time in 1937. They performed electrolysis of a molten combination 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. The first pound of 99 percent pure scandium metal was not produced until 1960.

Notable characteristics

Scandium is situated between calcium and titanium in period four of the periodic table. It is the first transition metal in period four. In addition, it lies at the top of group three (former group 3B), just above yttrium. Chemically, it resembles yttrium (and the rare earth metals) more than it resembles titanium.

Silvery when pure, scandium develops a slightly yellowish or pinkish cast when exposed to air. It is a soft, light metal. It is resistant to corrosion by acids. For example, it is not attacked by a 1:1 mixture of nitric acid(HNO3) and hydrofluoric acid (HF).

When added to weldable structural aluminum alloys, scandium strengthens the alloys by lowering the rate of recrystallization and associated grain growth in the heat-affected zones.

In most of its compounds, the oxidation state of scandium is +3. Thus scandium is sometimes seen as the oxide, Sc203, or the chloride, ScCl3.

Isotopes

Naturally occurring scandium is composed of one stable isotope, 45Sc. In addition, many radioactive isotopes have been produced artificially, with atomic mass numbers ranging from 36 to 60. The three most stable radioisotopes are: 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. The remaining radioactive isotopes have half-lives that are less than four hours, and the majority of these have half-lives that are less than two minutes.

Compounds

  • Scandium(III) chloride, scandium chloride, or scandium trichloride (ScCl3): The pure compound is a white crystalline solid that is hygroscopic (absorbs moisture from the air). It is an ionic compound with a high melting point (960 °C). It is primarily of interest in the research laboratory. At high temperatures, it reacts with scandium metal to produce a broad family of scandium chlorides, including Sc5Cl8 and Sc7Cl12. Scandium(III) chloride is used in halide lamps, optical fibers, electronic ceramics, and lasers.
  • Scandium(III) oxide, scandium oxide, or scandia (Sc2O3): This amorphous, white powder is an ionic compound. Given its resistance to heat and thermal shock, it is used in high-temperature systems. In addition, it is used in electronic ceramics and glass composition (as a helper material). The oxide will dissolve in alkali to form scandate salts. In this respect, it is more similar to aluminum oxide than to yttrium oxide or lanthanum oxide.

Applications

As a very rare metal, scandium has a limited number of applications, some of which are noted below.

  • The main application of scandium by weight is in aluminum-scandium alloys for minor aerospace industry components and for sports equipment—such as specially designed bikes, baseball bats, lacrosse sticks, and firearms—requiring strong, lightweight, high-performance materials. Yet titanium, being much more readily available and similar in lightness and strength, is more widely used, with tons of it used in some military aircraft.
  • Approximately 20 kilograms (kg) of scandium (as Sc2O3) is used annually in the United States to make high-intensity lights.[1]
  • Scandium iodide added to mercury-vapor lamps produces an efficient artificial light source that resembles sunlight and allows good color-reproduction with television cameras.
  • 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.[1]
  • Earlier, scandium-aluminum alloys were used in the nose cones of some Soviet submarine-launched ballistic missiles (SLBMs). The resulting nose cone was sufficiently strong to enable it to pierce the ice cap without damage, thus enabling a missile launch from a submarine under the Arctic ice cap.

See also

Footnotes

  1. ↑ 1.0 1.1 C.R. Hammond. CRC Handbook of Chemistry and Physics, 85th ed., Section 4; The Elements.

References
ISBN links support NWE through referral fees

  • Cotton, F. Albert and Wilkinson, Geoffrey. 1980. Advanced Inorganic Chemistry, 4th ed. New York: Wiley. ISBN 0-471-02775-8
  • Greenwood, N.N. and Earnshaw, A. 1998. Chemistry of the Elements, 2nd Edition. New York: Elsevier. ISBN 0750633654
  • Scandium Los Alamos National Laboratory. Retrieved December 9, 2007.
  • Scandium SPECTRUM Chemical Fact Sheet. Retrieved December 9, 2007.
  • Stwertka, Albert. 2002. A Guide to the Elements, 2nd ed. Oxford: Oxford University Press. ISBN 0195150279

External links

All links retrieved January 25, 2023.

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