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Home >> Chemistry Dictionary >>Alkaline Earth Metals - Alkanes (Paraffins)
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Alkali metals.
(1 group elements) The alkali metals (Li, NA, K, Rb, Cs, Fr) are never found in the elemental state in the nature, because they react rapidly and completely with virtually with all non-metals. As a group, they are very soft metals having bright silvery luster and are good conductors of electricity and heat. The great chemical reactivity of the alkali metals is a reflection of their relatively low first ionization energies. Lithium is used as a degasifier, deoxidizer and desulphuriser in industry. Sodium foil is used in photoelectric cell. It is also used in the production of artificial rubber, antiknock fluid, i.e., lead tetra ethyl, dyes, drugs and perfumes.
Sodium lamps are used to illuminate highways. Sodium-Potassium alloy is used in special thermometers employed for measuring high temperatures, as of furnaces. Rubidium and caesium and their alloys are used in manufacturing radio tubes and photo electric cells.
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Alkaline earth metals.
The elements Mg, Ca, Sr, Ba and which are very electropositive and form M2 + ions.
Alkaline.
An aqueous solution with a pH greater than 7
Alkaloid :
One of a group of nitrogenous organic compounds derived from plants and having diverse pharmacological properties. Alkaloids include morphine, cocaine, atropine, quinine, and caffeine, most of which are used in medicine as analgesics (pain relievers) or anaesthetics. Some alkaloids are poisonous, e.g., strychnine and conin and colchicines inhibits cell division.
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Alkyl halides ;
The organic compounds with general formula RX, where R is any simple alkyl or substituted alkyl group and X may be halides are not soluble in water, probably because of their inability to form hydrogen bonds.
Alkaline-earth metals.
The alkaline-earth metals are never found in the metallic form in nature, because like alkali metals, they are active reductants and react readily with a variety of non-metals. They can be prepared by electrolysis of their fused halides. These metals are all considerably harder than alkali metals.
Beryllium sheets are used for windows of X-ray tubes. Magnesium in the form of Grignard’s reagent is largely used for synthesis of may organic compounds. It is also used in the form of its alloys. pyrotechny and for igniting thermite in aluminothermic processes.
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Calcium is used for removing sulphur from petroleum, as reducing agent in the metallurgy of titanium, vanadium and chromium and for making high class steel.
Compounds of calcium are far more important than the metal itself.
Calcium oxide (quick lime) is used is the manufacture of bleaching powder, glass, calcium carbide, sugar, washing soda and caustic soda by carticizing process.
Calcium hydroxide (flaked lime) is used in the manufacture of powder and preparation of ammonia in the laboratory. When mixed with sand and water, it forms a mortar which is used as building material because it sets into a hard mass on keeping.
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Calcium carbonates is used in the preparation of lime and cement and as a flux in the smelting of iron ore. Precipitated chalk is employed in medicine, tooth paste and face powder.
Plaster of Paris (CaSO4,H2O) on mixing with times the weight of water, it forms a plastic mass that sets into a hard solid and hence, it is given name of plaster. It is used in surgery for immobilizing fractured limbs.
Calcium cyanamide (CaCN2) is a very good fertilizers. Stronium nitrate is used in fire works to get red fire and the hydroxide is used in refining os sugar
Alkalimetry.
Volumetric analysis which is using standard solutions of alkali to determined the amount of acid present.
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Alkanals.
Aldehydes. Compounds containing terminal R-CHO groups.
Alkanes (paraffins).
Saturated hydrocarbons with the genral formula CnH2n + 2. In systematic chemical nomenclature alkaline names end in the suffix-ane. They form a homologous series (the alkaline series) methane (CH4), ethane (C2H6), propane (C3H8) butane (C4H10), pentane (C5H12), etc. They lower members of the series are gases; the high-molecular weight alkanes are waxy solids. Alkanes are present in natural gas and petroleum. They can be made by heating the sodium salt of a carboxylic acid with soda lime:
RCOONa+ + Na+OH --->Na2CO3 + RH
Others methods include the Wurtz reaction and Kolbe’s methods.
Generally the alkanes are fairly unreactive. They form haloalkanes with halogens when irradiated with ultraviolet radiation.
Alkanolamines, Alkylolamines.
Hydroxyamines produced by the reaction of an alkene oxide with aqueous ammonia at 50-60°C. They are hygroscopic solids of low m.p., and usually occur as rather viscous, colourless liquids of ammoniacal odour. They are used a accelerators in rubber manufacture, as catalysts in certain polymerization reactions’ and as absorbents for acidic gases such as carbon dioxide and hydrogen sulphide. They form soaps with fatty acids; these are almost neutral in reaction and are used as detergents and emulsifying agents.
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