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Notes 2 Archive |
Gaffer Variety:
Elements 14 SN2 016:
By Willie Gaffer:
Scandium:
Scandium, symbol Sc, is a silvery-white metallic element found in various rare minerals and separated as a byproduct in the processing of certain uranium ores. The atomic number is 21, the atomic weight is 44.956, the melting point is 1,540°C, the boiling point is 2,850°C, and the specific gravity is2.99. It has an electron shell arrangement of 2, 8, 9, 2 and a valence of 3.
Scandium is one of the transition elements in the periodic table. Remember from Study Notes 2, SN2 006, that transition Elements are a series of chemical elements that share similar electron orbital structures and hence similar chemical properties. They are the elements in columns 3B through 12B of our periodic table.
The most pronounced similarities are that they are all metals and that most of them are hard, strong, and lustrous. They have high melting and boiling points, and are good conductors of heat and electricity. However, the range in these properties is rather broad. There is still a lot of confusion about the naming conventions for these tweener elements. Sometimes they are called rare earth elements, sometimes they are called transition elements.
A rare thing about scandium is it’s existence was predicted before it was discovered. This is an indication of the power of the periodic table in understanding the relationships between these elements. A Russian chemist, Dmitry Ivanovich Mendeleyev, predicted it eight years before its discovery. The only current use of this element is of a radioactive isotope which is used as a tracer in examining oil wells and pipelines.
Titanium:
Titanium, symbol Ti, is a very strong, low-density, highly corrosion-resistant, lustrous white metallic element that occurs in many places in igneous rocks. The atomic number is 22, the atomic weight is 47.90, the melting point is 1,660°C, the boiling point is 3,287°C, and the specific gravity 4.54. The electron shell arrangement is 2, 8, 10, 2 and the valence can be 2, 3, or 4.
Titanium is strong and light, making it ideal for use in alloys, especially in the airframe and space industry where weight and strength are critical. Other common titanium alloys are ferrocarbon titanium, cuprotitanium, and manganotitanium. It is also used to replace bones in surgery and for plumbing in food process where inertness is a real asset.
Vanadium:
Vanadium, symbol V, is a bright white, soft, ductile metallic element found in several minerals, notably vanadinite and carnotite, having good structural strength. The atomic number is 23, the atomic weight is 50.942, the melting point is 1,890°C, the boiling point is 3,000°C, and the specific gravity 6.11. The electron shell arrangement is 2, 8, 11, 2 and it has valences of 2, 3, 4, and 5.
Vanadium is one of the hardest of all metals. It ranks about
19th in abundance of the elements in the earth's crust, but it is never found in the pure state. I shows
up in combination with various minerals all over the earth. Vanadium-ore
minerals in the
The metal is used in many alloys such as ferrovanadium, nickel vanadium, and chrome vanadium. Chrome-vanadium steels are used in the production of springs and in transmission gears and other engine parts. It is also used in rust-resistant high-speed tools, as a carbon stabilizer in some steels, as a titanium-steel bonding agent. Titanium-vanadium alloys are used for missile cases, jet-engine housings, and nuclear-reactor components. Vanadium is used as a catalyst in the manufacture of sulfuric acid. I also has uses in photographic development and in the paint industry.
Chromium:
Chromium, symbol Cr, is a lustrous, hard, steel-gray metallic element, resistant to tarnish and corrosion and found primarily in chromite. Chromite is a widely distributed black to brownish-black chromium ore, FeCr2O4. The atomic number is 24, the atomic weight is 51.996, the melting point is 1,890°C, the boiling point is 2,482°C, and the specific gravity is 7.18. The electron shell configuration is 2, 8, 13, 1 and the valences are 2, 3, 6.
It is used as a catalyst, to harden steel alloys and produce stainless steels, in corrosion-resistant decorative plating, and as a pigment in glass.
The element was discovered in 1797 It was named by the French chemist Louis Nicolas Vauquelin, who discovered it in 1797. Chromium is derived from the Greek word chroma, which means color. This element shows up in its compounds as many different colors. Chromium is a common element, ranking about 21st in abundance among the elements in the earth’s crust. A number of the precious gemstones have their distinctive color due to chromium compounds. Some paint pigments such as chrome yellow are based on compounds of chromium.
More than half the chromium produced is used in metallic products. The major use of chromium is in alloys of iron, nickel, or cobalt. Chromium gives hardness, strength, and corrosion resistance to the alloy. In the stainless steels, chromium makes up 10 percent or more of the final composition. Because of its hardness, an alloy of chromium, cobalt, and tungsten is used for high-speed metal-cutting tools. It is also used as body trim on automobiles and other vehicles. The extensive use of chromite as a refractory is due to its high melting point, its moderate thermal expansion, and the stability of its crystalline structure.