   #copyright

Scandium

2007 Schools Wikipedia Selection. Related subjects: Chemical elements

          Element 21 could also refer to the golf company who made the
          first space golf drive.


                21              calcium ← scandium → titanium
                 -
                ↑
                Sc
                ↓
                Y

                                  Periodic Table - Extended Periodic Table

                                                                   General
                                     Name, Symbol, Number scandium, Sc, 21
                                         Chemical series transition metals
                                              Group, Period, Block 3, 4, d
                                                  Appearance silvery white
                                           Atomic mass 44.955912 (6) g/mol
                                     Electron configuration [Ar] 3d^1 4s^2
                                            Electrons per shell 2, 8, 9, 2
                                                       Physical properties
                                                               Phase solid
                                      Density (near r.t.) 2.985 g·cm^−3
                                    Liquid density at m.p. 2.80 g·cm^−3
                                                     Melting point 1814  K
                                                    (1541 ° C, 2806 ° F)
                                                      Boiling point 3109 K
                                                    (2836 ° C, 5136 ° F)
                                          Heat of fusion 14.1 kJ·mol^−1
                                   Heat of vaporization 332.7 kJ·mol^−1
                          Heat capacity (25 °C) 25.52 J·mol^−1·K^−1

   CAPTION: 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^−1
                                                  2nd: 1235.0 kJ·mol^−1
                                                  3rd: 2388.6 kJ·mol^−1
                                                      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^−1·K^−1
                                      Thermal expansion ( r.t.) (α, poly)
                                                           10.2 µm/(m·K)
                                                  Young's modulus 74.4 GPa
                                                    Shear modulus 29.1 GPa
                                                     Bulk modulus 56.6 GPa
                                                       Poisson ratio 0.279
                                                  Brinell hardness 750 MPa
                                             CAS registry number 7440-20-2
                                                         Selected isotopes

                 CAPTION: Main article: Isotopes of scandium

                              iso    NA  half-life DM    DE ( MeV)    DP
                            ^44 mSc 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 -

                                                                References

   Scandium ( IPA: /ˈskandiəm/) is a chemical element in the periodic
   table that has the symbol Sc and atomic number 21. A soft, silvery,
   white metal, scandium ore occurs in rare minerals from Scandinavia and
   elsewhere, and it is sometimes considered along with yttrium, and the
   lanthanides and actinides, to be a rare earth.

Notable characteristics

   Scandium is a rare, soft, silvery, very light metallic 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(HNO[3]) and
   hydrofluoric acid, HF. The rarity of scandium is not an arbitrary fact.
   In this area of atomic numbers, 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.

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.

   It is also used in various lacrosse sticks. The light yet strong metal
   is needed for precise accuracy and speed.

   Approximately 20 kg (as Sc[2]O[3]) of scandium is used annually in the
   United States to make high-intensity lights. Scandium iodide added to
   mercury-vapor lamps produces an efficient artificial light source that
   resembles sunlight, and which allows good colour-reproduction with TV
   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.

   The main application of scandium by weight is in aluminium-scandium
   alloys 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.

   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[3]Sc 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
   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.

   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.

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 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 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 kilograms of euxenite, producing about
   2.0 grams of a very pure scandium oxide (Sc[2]O[3]).

   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 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% pure scandium metal was not
   produced until 1960.

Occurrence

   Scandium is distributed sparsely on earth, occurring only as trace
   quantities in many minerals. 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 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.

   The blue colour of the aquamarine variety of beryl is thought to be
   caused by 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 reducing 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.

Compounds

   The most common oxidation state of scandium in 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 Scandium compounds.

Isotopes

   Naturally occurring scandium is composed of 1 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-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 ^44mSc (t[½] 58.6 h).

   The isotopes of scandium range in atomic weight from 40 amu (^40Sc) to
   54 amu (^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.

   Retrieved from " http://en.wikipedia.org/wiki/Scandium"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
