Science / Periodic Table of Elements / Scandium (Sc): Atomic number: 21, Atomic mass: 44.9559 g.mol -1, Electronegativity: unknown, Density: 3.0 g.cm-3 at 20°C, Melting point: 1541 °C, Boiling point: 2836 °C, Vanderwaals radius: 0.161 nm, Ionic radius: 0.083 nm (+3), Isotopes: 7, Electronic shell: [ Ar ] 3d1 4s2, Energy of first ionisation: 640.5 kJ.mol -1, Energy of second ionisation: 1233 kJ.mol -1, Energy of third ionistion: 2389 kJ.mol -1, Energy of fourth ionisation: 7089 kJ.mol -1, Discovered by: Lars Nilson in 1879. Scandium is a soft, silvery transition element which occurs in rare minerals from Scandinavia. It develops a slightly yellowish or pinkish cast when exposed to air. Scandium tarnished in air and burn easily, once it has been ignited. It reacts with water to form hydrogen gas and will dissolve in many acids. Pure scandium is produced by heating scandium fluoride (ScF3) with calcium metal. Applications: Scandium is one of the rare chemicals, that can be found in houses in equipment such as colour televisions, fluorescent lamps, energy-saving lamps and glasses. The use of scandium is still growing, due to the fact that it is suited to produce catalysers and to polish glass. The main application by volume is in aluminium-scandium alloys for the aerospace industry and for sports equipment (bikes, baseball bats, etc.) which rely on high performance materials. It has been shown to reduce solidification cracking during the welding of high strength aluminium alloys. Scandium in the environment: Scandium can rarely be found in nature, as it occurs in very small amounts. Scandium is usually found only in two different kinds of ores. Thortveitite is the primary source of scandium with uranium mill tailings by-products also being an important source. World production amount to only 50 kg per year. There is no estimate of how much is potentially available. Scandium is only the 50th most abundant element on hearth, it is distributed widely, occurring in trace quantities in over 800 minerals. The blue color of the aquamarine variety of beryl is thought to be caused by scandium. Only about 3% of plants that were analysed for scandium shows its presence, and even those amounts were tiny, with vegetable having only 5 ppb although grass has 70 ppb.
Science / Tides and Currents / Small Tropic Range (SC): Difference in height between tropic lower high water and tropic higher low water. MORE