Lithium in Periodic Table
Lithium (Li), atomic number 3, the lightest solid chemical element of Group 1 (IA) in the periodic table or alkali metal family has wide industrial application in the present day of the world. The systematic study of alkali metal (lithium, sodium, and potassium) in inorganic chemistry describes their physical and chemical properties which can readily understand by the outer electron configuration of the elements. The alkali metal, lithium is soft, low melting (melting point 180.5 °C), silvery-white body-centered cubic crystal lattice at room temperature but at low temperature, it forms a hexagonal close pack structure.
The electron configuration of the lithium atom, 1s2 2s1, the only 2s1 electron of the metal takes part in metallic bonding. The large difference between the first and second ionization energy of lithium suggests that the preferred oxidation number or state of metal will be +1 and preferred to form ionic chemical bonding or compounds in chemistry. All the alkali metals give characteristic flame colour due to easy excitation by electromagnetic spectrum (lithium – crimson, sodium – yellow, potassium – violet, rubidium – red-violet, cesium – blue). This fact of alkali metals developed the analytical method for precise estimation by flame photometer.
Discovery and Occurrence
Lithium was discovered by Swedish chemist Johan August Arfvedson in 1817 in the mineral petalite, the name was chosen from Greek latter lithos = stone. The chemical element lithium occurs in crustal rocks (18 ppm) comparable to gallium (18 ppm) and niobium (20 ppm) in the earth’s environment. The aluminum silicate is the main minerals occurs in the form of spodumene, LiAl(SiO3)3 about 2.5 to 3 percent and lepidolite, LiF, LiOH, Al2(SiO3)3 about 3.8 to 5.6 percent in United States, Canada, Brazil, Argentina, Soviet Union, Spain, and Congo. The very low terrestrial or cosmic abundance of lithium compared to other alkali metals describe by its small nuclear charge and low potential barrier which may be facilitated nuclear reaction to heavier elements like beryllium or boron. It also occurs in many springs and some radioactive decay minerals like carnallite, ashes of planets, in taboo, milk, and blood of living animals. Searles Lake in California is an important source of nearly dry and alkaline (pH scale = 9.5) lithium metal. In the 19th century, the United States was the largest producer of chemical elements and compounds like lithium carbonate, Li2CO3 but in this century, Australia, Chile, and Portugal are the largest commercial suppliers of the metal or compound.
Extraction of Element
The alkali metals beings most electropositive and never found in nature in elementary states. Due to electropositivity, alkali metals readily react with water and cannot be produced by electrolysis but fused chloride and hydroxide are used for the preparation of lithium and sodium. The major commercial form of the metal like lithium carbonate, Li2CO3, produced from ores or brines by different processes and uses largely in the chemical industry. About 1000 tonnes of lithium metal and several thousands of salts are prepared annually for various purposes of use.
Chemical Properties and Reactivity
The large difference between the first and second ionization energy of lithium suggests that the preferred oxidation state of the metal describe by +1 oxidation state or the major chemistry describe by the form of Li+ ion. In solution, the Li+ ion stabilizes by high solvation energy. The reactivity of the alkali family increases from lithium to cesium, except nitrogen molecule. Therefore, at 25 °C, water reacts with lithium very slowly, sodium reacts vigorously, and potassium, rubidium, or cesium react with an explosion. It burnt in air or oxygen to form Li2O and a trace amount of Li2O2 but it reacts with nitrogen slowly at room temperature and rapidly to give ruby red crystalline solid Li3N. The poor reactivity of the element is also illustrated by the fact that lithium cannot replace weekly acidic hydrogen from phenyl-acetylene but other alkali metals liberate hydrogen from this chemical compound.
The properties or behavior of the lithium molecule and its compounds differ significantly from the alkali metals family and resembles magnesium due to the diagonal relationship in the periodic table. Many simple salts of metal are normally hydrated and anhydrous salts are hygroscopic in nature (LiCl, LiBr, LiI, etc). The structure of LiClO4, 3H2O, and Mg(ClO4)2, 6H2O are similar in nature, both contain octahedral groups. The electrode potential for the redox reaction of the lithium has the lowest value due to the highest ionization energy and small size of the atom.
Uses of Lithium
Lithium form low density and good alloy with aluminum and magnesium like LA-141 (Li = 14 percent, aluminum 1 percent, and magnesium 85 percent) uses for aircraft construction. Lithium stearate (LiOH + tallow) is used as a thinner or gelling agent for transformation oils into lubricating greases which are highly water-resistant materials. A compound like lithium carbonate is extensively used in cells for the extraction of aluminum by the larger flowing of current or reducing the production cost, used as a flux in making porcelain, enamel, and specially toughened glass, used in medicine for the treatment of manic depressive psychoses.
Lithium hydroxide is used for absorption of carbon dioxide in space capsules and submarines, the elemental hydride uses to generate hydrogen for military or metrological requirements. Several organolithium compounds are widely used in the organic synthesis of hydrocarbons like alkanes or paraffin and alkenes or olefins. In storage batteries or cells, Li-Si and Li-Al alloy used as an anode in molten lithium chloride or potassium chloride are under trial to prepare electric current. Lithium may be used to prepare tritium (isotopes of hydrogen, which is a promoting fuel in the nuclear power generation process by the nuclear fusion reaction.