Chemical and physical characteristics of lithium, and its reaction with oxygen

Properties of the lightest metal

[Deposit Photos]

Lithi­um (Li) is a chem­i­cal el­e­ment with the atom­ic num­ber of 3 and an atom­ic mass of 6.941. Lithi­um is en­coun­tered in na­ture in the form of the two sta­ble nu­clides 6Li (7.6% by mass) and 7Li (92.4%). In the pe­ri­od­ic ta­ble, lithi­um is lo­cat­ed in the sec­ond pe­ri­od, in the first group, and the el­e­ment is clas­si­fied as an al­ka­line met­al. In com­pounds, lithi­um dis­plays an ox­i­da­tion state of +1. In the form of a sim­ple el­e­ment, lithi­um, is a mal­leable, soft, light met­al of a sil­very col­or.

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Chem­i­cal and phys­i­cal char­ac­ter­is­tics of lithi­um

Lithi­um is the light­est of all met­als, with a den­si­ty of 0.534 g/cm3. It melts at a tem­per­a­ture of 180.5 de­grees Cel­sius and boils at a tem­per­a­ture of 1,330 de­grees Cel­sius.

Lithi­um has a high ac­tiv­i­ty, and the met­al en­ters into a re­ac­tion with oxy­gen and ni­tro­gen in the air un­der or­di­nary con­di­tions. For this rea­son, in air lithi­um swift­ly ox­i­dizes with the for­ma­tion of a dark coat­ing of in­ter­ac­tion prod­ucts, and the equa­tions of the re­ac­tions are:

4Li + O₂ = 2Li₂O,

6Li + N₂ = 2Li₃N.

Pieces of lithium floating in oil [Wikimedia]

Dis­cov­ery of lithi­um and lo­ca­tion of the el­e­ment in na­ture

Lithi­um was dis­cov­ered by the Swedish sci­en­tist Ar­fwed­son in 1817 – the chemist first found the el­e­ment in the min­er­al petal­ite, and then in spo­dumene and lep­i­do­lite. The met­al re­ceived its name as it was found in “stones” (the Greek word for stone is Litos). In 1818, the Ger­man chemist C. G. Gmelin first ob­served a red flame that is char­ac­ter­is­tic for lithi­um salts. In 1821, the Eng­lish chemist William Thomas Brande iso­lat­ed the met­al by elec­trol­y­sis. Lithi­um was first ob­tained in larg­er quan­ti­ties in 1855, by the elec­trol­y­sis of molten chlo­ride. The equa­tion of the re­ac­tion:

2Li­Cl = 2Li + Cl₂.

Lithi­um is wide­spread in the earth’s crust, ac­count­ing for around 3% of its mass. The main min­er­als con­tain­ing lithi­um are petal­ite, spo­dumene, lep­i­do­lite and am­bly­go­nite.

Lepidolite [Deposit Photos]

Lithi­um is con­tained in sev­er­al rock-form­ing min­er­als and is present in min­er­al­ized wa­ters and the brine of cer­tain lakes.

Click here to learn more about prop­er­ties of lithi­um and oth­er met­als.

Lithi­um – re­ac­tion with oxy­gen, ap­pli­ca­tion of the met­al

Al­ka­line met­als and their com­pounds are wide­ly used in tech­nol­o­gy. Lithi­um is used in nu­cle­ar en­er­gy. The iso­tope 6Li serves as an in­dus­tri­al source for the pro­duc­tion of tri­tium, and the iso­tope 7Li is used as a heat con­duc­tor. LiF is used in the smelt­ing of alu­minum. Lithi­um and its com­pounds are also used as an ad­di­tive to rock­et fuel.

[Flickr, Creative commons by Steve Jurvetson is licensed under CC BY 2.0]

Lu­bri­cants con­tain­ing lithi­um com­pounds pre­serve their prop­er­ties at high tem­per­a­tures. Lithi­um hy­drox­ide is present in the elec­trolyte of al­ka­line bat­ter­ies, in­creas­ing their ser­vice pe­ri­od by two to three times. Lithi­um is also used in ce­ram­ic, glass and oth­er branch­es of the chem­i­cal in­dus­try. Gen­er­al­ly, by its im­por­tance in mod­ern tech­nol­o­gy this met­al is one of the most im­por­tant el­e­ments. The re­ac­tion of lithi­um with oxy­gen leads to the for­ma­tion of lithi­um ox­ide Li₂O – a col­or­less crys­talline sub­stance with a melt­ing tem­per­a­ture of 1,438 de­grees Cel­sius, and a boil­ing tem­per­a­ture of around 2,600 de­grees Cel­sius. Lithi­um ox­ide is ob­tained through the di­rect ox­i­da­tion of metal­lic lithi­um at a tem­per­a­ture over 200 de­grees Cel­sius, and also the break­down of lithi­um hy­drox­ide LiOH, lithi­um ni­trate LiNO₃ and lithi­um car­bon­ate LiNO₃.

Lithi­um ox­ide Li₂O eas­i­ly in­ter­acts with wa­ter with the for­ma­tion of lithi­um hy­drox­ide, LiOH. This re­ac­tion is ac­com­pa­nied by in­tense heat­ing; LiOH ab­sorbs CO₂ from the air, form­ing lithi­um car­bon­ate, Li₂­CO₃.