|Name, Symbol, Number||Scandium, Sc, 21|
|Chemical series||Transition metals|
|Group, Period, Block||3, 4 , d|
|Density, Hardness||2985 kg/m3, U/K|
|Atomic weight||44.955910 amu|
|Atomic radius (calc.)||160 (184) pm|
|Covalent radius||144 pm|
|van der Waals radius||no data|
|Electron configuration||[Ar]3d3d1 4s2|
|e- 's per energy level||2, 8, 9, 2|
|Oxidation states (Oxide)||3 (weak base)|
|State of matter||Solid (__)|
|Melting point||1814 K (2806 °F)|
|Boiling point||3103 K (5126 °F)|
|Molar volume||15.00 ×1010-3 m3/mol|
|Heat of vaporization||314.2 kJ/mol|
|Heat of fusion||14.1 kJ/mol|
|Vapor pressure||22.1 Pa at 1812 K|
|Speed of sound||no data m/s at 293.15 K|
|Electronegativity||1.36 (Pauling scale)|
|Specific heat capacity||568 J/(kg*K)|
|Electrical conductivity||1.77 106/m ohm|
|Thermal conductivity||15.8 W/(m*K)|
|1st ionization potential||633.1 kJ/mol|
|2nd ionization potential||1235.0 kJ/mol|
|3rd ionization potential||2388.6 kJ/mol|
|4th ionization potential||7090.6 kJ/mol|
|5th ionization potential||8843 kJ/mol|
|6th ionization potential||10679 kJ/mol|
|7th ionization potential||13310 kJ/mol|
|8th ionization potential||15250 kJ/mol|
|9th ionization potential||17370 kJ/mol|
|10th ionization potential||21726 kJ/mol|
|Most Stable Isotopes|
|SI units & STP are used except where noted.|
Notable CharacteristicsScandium is a rare, soft, silvery, trivalent, very light metallic element that develops a slightly yellowish or pinkish cast when exposed to air. This element resembles yttrium and rare earth metals more than it resembles aluminum or titanium (which are closer on the periodic table). The most common oxidation state of scandium is +3 and this metal is not attacked by a 1:1 mixture of HNO3 and 48% HF.
ApplicationsApproximately 20 kg of scandium (as Sc2O3) are used annually in the United States to make high-intensity lights. The radioactive isotope Sc-46 is used in oil refinery crackers as a tracing agent. When scandium iodide is added to mercury vapor lamps a highly efficient artificial sunlight-like light source is produced which is used in indoor or night-time color televisions. Scandium also has a much higher melting point than aluminum, and has been studied for possible use in spacecrafts.
HistoryScandium (Latin Scandia meaning "Scandinavia") was discovered by Lars Fredrick Nilson in 1879 while he and his team were looking for rare earth metals. Nilson used spectrum analysis to find the new element within the minerals euxenite and gadolinite. To isolate the element he processed 10 kilograms of euxenite with other rare-earth residues to obtain about 2 gramss of very pure scandium oxide (Sc2O3).
Dmitri Mendeleev, in 1869, predicted the existence and some properties of this element, which he called ekaboron, using his periodic law. Per Theodor Cleve discovered scandium oxide at about the same time as Nilson but unlike Nilson, Cleve determined that scandium was identical to ekaboron.
In 1937 metallic scandium was prepared for the first time by electrolysis of a eutectic melt of potassium, lithium, and scandium chlorides at 700 to 800° C. Tungsten wire in a pool of liquid zinc were the electrodes in a graphite crucible. The first pound of 99% pure scandium metal wasn't produced until 1960.
Rare minerals from Scandinavia and Malagasy such as thortveitite, euxenite and gadolinite are the only known concentrated sources of this element (which is never found as a free metal).
Element 21 is the 23rd most abundant element in the sun and similar stars but on earth it is only the 50th most abundant element. Scandium is distributed widely on earth, occurring in trace quantities in over 800 minerals. The blue color of the aquamarine variety of beryl is thought to be caused by scandium. It is an important part of the rare mineral thortveitite and is found in residues that remain after tungsten is extracted from Zinnwald wolframite.
Thortveitite is the primary source of scandium with uranium mill tailings by-products also being an important source. Pure scandium is commercially produced by reducing scandium fluoride with calcium metal.
Naturally occurring scandium is composed of 1 stable isotope Sc-45. 13 radioisotopes have been characterized with the most stable being Sc-46 with a half-life of 83.79 days, Sc-47 with a half-life of 3.3492 days, and Sc-48 with a half-life of 43.67 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 states with the most stable being Scm-44 (t½ 58.6 h).
The isotopes of scandium range in atomic weight from 39.978 amu (Sc-40) to 53.963 amu (Sc-54). The primary decay mode before the only stable isotope, Sc-45, is electron capture and the primary mode after is beta emission. The primary decay products before Sc-45 are element 20 (calcium) isotopes and the primary products after are element 22 (titanium) isotopes.
Scandium metal powder is combustible and presents a fire hazard.