Chemistry

An Overview about the Chemical Element Lithium



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Lithium ions differ from sodium and potassium ions in that they do not have an apparent physiological role in the body. Lithium is used however in the pharmaceutical industry to treat bipolar disorder. An example of such a drug is lithium carbonate or Li2CO3.

Lithium metal is less reactive than sodium and potassium metals. As we go down the periodic table the reactivity of the alkali metals increases. This is manifested by the more exothermic reactions of the metals with water as we go from lithium to caesium.

Lithium has the electronic configuration of helium plus an additional electron in the 2s orbital. Helium is an inert gas, therefore, the lithium ion is chemically stable because it has the electronic configuration of the chemically stable helium atom.

LIthium is a reactive metal to a lesser extent than sodium and potassium. It reacts exothermically with water to generate the oxide of lithium in addition to liberating hydrogen gas according to the following equation:

Li + H2O -> Li2O + H2

Lithium is used often in organic chemistry. Organolithium compounds are used as strong bases such as butyllithium or BuLi which is a powerful base. BuLi is generated by a reaction of butyl halide with an alkyllithium.

Lithium is a soft metal to a lesser extent than the other alkali metals. This is so due to the relatively small ionic diameter of Li+ of 152 pm in contrast to sodium below it in the periodic table which has an ionic diameter of 204 pm.

Lithium ion ionic diameter is comparable to that of magnesium which has an ionic diameter of 144 pm. Therefore the chemistry of the lithium ion and the magnesium +2 ion is comparable to each other. An example is the compound LiF which is not soluble in water like MgF2.

LIthium like magnesium reacts with the relatively inert nitrogen molecule to generate nitrides of lithium and of magnesium. The small size of the lithium ion makes it easily hydrated in aqueous solutions. The lithium ion is harder than all other alkali metals. This is so due to it small size.

It has the highest melting point of all the alkali metals. It melts at 180.6 degrees Celsius. Its boiling point is also the highest among all the alkali metals. It boils at 1342 degrees Celsius. Its density is the lowest of all alkali metals. Its density is 0.534 g/cm3.

LIthium has a characteristic flame color when tested in atomic absorption spectroscopy. Its crystal has the body centered cubic lattice. Its color is silvery/white color. Its atomic number is 3 with a total of 3 electrons. It has two naturally occurring isotopes.

In organic solvents which are hydrophobic lithium is solvated using crown ethers. Due to its charge it dissolves little in non-polar solvents. So there is a need for crown ethers to dissolve lithium ions as well as other alkali metals ions with higher ionic diameter.

Lithium has many compounds. An example is lithium carbonate or Li2CO3 which is the most important compound of lithium industrially. As was mentioned previously this compound is used to treat bipolar disorder. The other compound of lithium which is also important is LiOH. This compound is a base which is used in the manufacture of grease, especially lithium stearate grease.

Another compound of lithium which is also important is LiH or lithium hydride. This compound is a base which is important for the production of molecular hydrogen by a reaction with water.

An important reagent of lithium in organic chemistry is LiAlH4 or lithium aluminium hydride. This compound is a reducing agent which is used for example in the reduction of ketone's to alcohols.

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