tailieunhanh - Lithium

Introduction Because of its high reactivity, lithium metal is not found in its native state. The main sources of lithium are brine wells when subjected to evaporation as well as igneous rocks such as spodumine, lepidolite, and petalite. The name lithium comes from the Greek word ‘lithos’ meaning stone. Its discovery is generally attributed to Johan A. Arfvedson, who first identified it in 1817. Lithium metal was isolated by Sir Humphrey Davy and William Thomas Brande, and R. W. E. Bunsen and A. Maththiessen, in 1855 by the electrolysis of lithium chloride. . | Lithium RJ Brodd Broddarp of Nevada Inc. Henderson NV USA 2009 Elsevier . All rights reserved. Introduction Because of its high reactivity lithium metal is not found in its native state. The main sources of lithium are brine wells when subjected to evaporation as well as igneous rocks such as spodumine lepidolite and petalite. The name lithium comes from the Greek word lithos meaning stone. Its discovery is generally attributed to Johan A. Arfvedson who first identified it in 1817. Lithium metal was isolated by Sir Humphrey Davy and William Thomas Brande and R. W E. Bunsen and A. Maththiessen in 1855 by the electrolysis of lithium chloride. The first commercial production of lithium metal took place in Germany in 1923 when Metallgesellschaft AG used electrolysis to treat a molten mixture of lithium and potassium chlorides. The same process is used today. Lithium is used as a polymerization initiator for a variety of organic and polymer materials. Lithium metal is the lightest metal and belongs to the alkali metals group in the Periodic Table. It has one electron outside the noble gas core with low ionization energy. Lithium is a silvery white metal with a density of gcm 3 a good conductivity of X 106Scm and a melting point of 181 C. It forms compounds with a high degree of ionic bonding. Lithium compounds have high lattice energy and are very stable. Its salts are completely dissociated in aqueous solutions. Lithium metal oxidizes readily in humid air. It is an alkali metal of group 1 with an atomic weight of and a high electrochemical equivalent of Ah g . Lithium is a powerful reducing agent with an electrode potential of V versus hydrogen. It has a low ionization energy and forms a single positively charged cation Li . The combination of high voltage and low equivalent weight makes it a desirable negative electrode for high-energy primary and rechargeable batteries as well as for processes involving reduction reactions. In aqueous