LITHIUM [Li]

Characteristics

An: 3

N: 4

Am: [6.941 (2)] g/mol

Group No: 1

Group Name: Alkali metal

Block: s-block

Period: 2

State: solid at 298 K

Colour: silvery white/grey

Classification: Metallic

Boiling Point: 1615K (1342^oC)

Melting Point: 453.69K (180.54^oC)

Density: 0.534g/cm³

Discovery Information

Who: Johann Arfvedson

When: 1817

Where: Sweden

Name Origin

Greek: lithos (stone). "Lithium" in different languages.

Sources

Lithium is widely distributed but does not occur in nature in its free form. Because of its reactivity, it is always found bound with one or more other elements or compounds. Found in trace amounts in the minerals; spodumene (LiAl(SiO₃)₂), amblygonite (Li,Na)AlPO₄(F,OH)), lepidolite (KLi₂Al(Al,Si)₃O10(F,OH)₂). Most commercial lithium is recovered from brines sources in Chile. Also obtained by passing electric charge through melted lithium chloride. Around 39 thousand tons are produced every year.

Abundance

Universe: 0.006 ppm (by weight)

Sun: 0.00006 ppm (by weight)

Carbonaceous meteorite: 1.7 ppm

Earth’s Crust: 20 ppm

Seawater: 0.18 ppm

Human: 30 ppb by weight; 27 ppb by atoms

Gambar Lithium is found in trace amounts in the mineral lepidolite

Uses

Used in batteries, ceramics, glass, lubricants, alloy hardeners, pharmaceuticals, hydrogenating agents, heat transfer liquids, rocket propellants, vitamin A synthesis, nuclear reactor coolant, underwater buoyancy devices and the production of tritium. Deoxidizer in copper and copper alloys.

Alloys of the metal with aluminium, cadmium, copper, and manganese are used to make high performance aircraft parts. Lithium salts such as lithium carbonate (Li2CO₃), lithium citrate, and lithium orotate are mood stabilizers (the effect is due to the lithium ion, so the type of salt is unimportant). They are used in the treatment of bipolar disorder, since unlike most other mood altering drugs, they counteract both mania and depression. Lithium can also be used to augment other antidepressant drugs. Useful amounts of lithium for this use are only slightly lower than toxic amounts, so the blood levels of lithium must be carefully monitored during such treatment.

Lithium metal is used as a catalyst in some types of methamphetamine production, particularly in illegal amateur "meth labs."

History

Petalite (LiAlSi₄O₁₀), which has lithium in it, was discovered by the Brazilian scientist Jose Bonifacio de Andrade e Silva in the late 1700s on a trip to Sweden. Lithium was discovered by Johan August Arfwedson in 1817. Arfwedson found the new element within the minerals spodumene and lepidolite in a petalite ore (LiAl(Si₂O₅)₂) that he was analyzing during a routine investigation of some minerals from a mine on the island Uto in Sweden. In 1818 Christian Gmelin was the first to observe that lithium salts give a bright red colour in flame. Both men tried and failed to isolate the element from its salts.

The element was not isolated until William Thomas Brande and Sir Humphry Davy later used electrolysis on lithium oxide in 1818. Robert Bunsen and Matiessen isolated larger quantities of the metal by electrolysis of lithium chloride in 1855.

Commercial production of lithium metal was achieved in 1923 by the German company Metallgesellschaft through using electrolysis of molten lithium chloride and potassium chloride. It was apparently given the name "lithium" because it was discovered from a mineral while other common alkali metals were first discovered from plant tissue.

Notes

Lithium is a soft, silvery metal, so soft that it can be cut with a sharp knife. It is the lightest of all metals and has a density only half that of water.

Lithium is one of only three elements - and the only metal - created in the first moments of the Big Bang. (The other two elements are hydrogen and helium, which according to cosmologists, were created in much greater abundance than lithium.)

Hazards

Lithium causes serious burns, especially when in contact with damp skin. Contact with the eyes may cause serious permanent damage.

It is the only metal that reacts with nitrogen at room temperature. Near its melting point, lithium ignites in air. Lithium posses a dangerous fire and explosion risk when exposed to water, acids or oxidizing agents. Lithium fires are difficult to extinguish, requiring special chemicals designed to smother them. It reacts exothermally with nitrogen in moist air at high temperatures. In solution lithium is toxic and targets the central nervous system.

Lithium Compounds

Lithium bromide LiBr

An extremely hygroscopic and often used as a dessicant. Along with lithium chloride (LiCl), it is frequently used in air conditioning and industrial drying systems.

Lithium carbonate Li₂CO₃

A chemical compound that is used as a mood stabilizer in psychiatric treatment of manic states and bipolar disorder.

Lithium citrate Li₃C₆H₅O₇

A chemical compound that is used as a mood stabilizer in psychiatric treatment of manic states and bipolar disorder. Lithium fluoride LiF It is a white, inorganic, crystalline, ionic, solid salt (under standard conditions). It transmits ultraviolet radiation more efficiently than any other substance. Uses include specialized UV optics and thermoluminescent dosimeters.

Lithium hydride LiH

It has numerous uses, as a desiccant, among them as a precursor in chemical synthesis (in particular for lithium aluminium hydride), in hydrogen generators, as both a coolant and shielding in nuclear reactors, and in the manufacture of ceramics. One of its most infamous usages is as the fusion fuel in thermonuclear weapons, in the deuteride form; when this is irradiated with neutrons, lithium forms tritium (along with more neutrons, creating a chain reaction), which is a key ingredient in the thermonuclear reactions which power these devices.

Lithium hydroxide LiOH

It is made by mixing lithium and water. A reaction so violent, and so much heat is given off, that the hydrogen produced burns with a bright purple flame. For this reason, lithium batteries must be kept away from water. Lithium hydroxide is used in breathing gas purification systems for spacecraft, submarines, and rebreathers to remove carbon dioxide (CO₂) from exhaled gas by producing lithium carbonate (Li₂CO₃).

Lithium iodide LiI

Lithium iodide is used as an electrolyte for high temperature batteries. It is also used for long life batteries as required, for example, by cardiac pacemakers. The solid is used as a phosphor for neutron detection.

Lithium nitrate LiNO₃

An oxidizing agent used in the manufacture of fireworks and flares. It is deliquescent.

Lithium perchlorate LiClO₄ [Irritant : Oxidizer]

Lithium perchlorate is used as a fuel and oxygen source in some chemical oxygen generators. As it has both the highest weight to oxygen and volume to oxygen ratio of all perchlorates, it is especially advantageous in aerospace applications. It is also used extensively as an electrolyte in lithium batteries.

Lithium peroxide Li₂O₂

It is used in air purifiers such as those used in submarines to absorb carbon dioxide and release oxygen.

Lithium sulfate Li₂SO₄

It is used to treat bipolar disorder.

Lithium tantalate LiTaO₃

A crystalline solid which possesses unique optical, piezoelectric and pyroelectric properties which make it valuable for infrared motion detectors, terahertz generation and detection, surface acoustic wave applications, cell phones and possibly pyroelectric nuclear fusion.

Reactions of Lithium

Reactions with water

Lithium metals reacts slowly with water to form a colourless solution of lithium hydroxide (LiOH) and hydrogen gas, H₂. The resulting solution is basic because of the dissolved hydroxide. The reaction is exothermic, but the reaction is slower than that of sodium.

2Li_(s) + H₂O_(l) --> 2LiOH_(aq) + H_2(g)

Reactions with air

When lithium is burned in air, the main product is the white oxide lithium oxide, Li₂O. Some lithium peroxide, Li₂O₂, also white, is also produced.

4Li_(s) + O_2(g) --> 2Li₂O_(s)

2Li_(s) + O_2(g) --> 2Li₂O_2(s)

Lithium reacts with nitrogen, N₂, to form lithium nitride, Li₃N. No other Gruop 1 element does anything similar, but the group 2 metal magnesium forms a similar nitride.

6Li_(s) + N_2(g) --> 2Li₃N_(s)

Reactions with halogens

Lithium metal reacts vigorously with all the halogens to form lithium halides.

2Li_(s) + F_2(g) --> LiF_(s)

2Li_(s) + Cl_2(g) --> LiCl_(s)

2Li_(s) + Br_2(g) --> LiBr_(s)

2Li_(s) + I_2(g) --> LiI_(s)

Reactions with acids

Lithium metal dissolves readily in dilute sulphuric acid to form solutions containing the aquated Li(I) ion together with hydrogen gas, H₂.

2Li_(s) + H₂SO_4(aq) --> 2Li⁺_(aq) + SO₄^2-_(aq) + H_2(g)

Reactions with bases

Lithium metals reacts slowly with water to form a colourless solution of basic lithium hydroxide (LiOH) and hydrogen gas (H₂). The reaction continues even when the solution becomes basic. The resulting solution is basic because of the dissolved hydroxide. The reaction is exothermic, but the reaction is slower than that of sodium. As the reaction continues, the concentration of the hydroxide increases.

2Li_(s) + 2H₂O --> 2LiOH_(aq) + H_2(g)

Occurrence and Production of Lithium

On Earth, lithium is widely distributed, but because of its reactivity does not occur in its free form. In keeping with the origin of its name, lithium forms a minor part of almost all igneous rocks and is also found in many natural brines. Lithium is the thirty-first most abundant element, contained particularly in the minerals spodumene (LiAl(SiO₃)₂), lepidolite ((KLi₂Al(Al,Si)₃O₁₀(F,OH)₂), petalite (LiAlSi₄O₁₀), and amblygonite ((Li,Na)AlPO₄(F,OH)). On average, Earth’s crust contains 65 parts per million (ppm) lithium.

Since the end of World War II, lithium metal production has greatly increased.

The metal is separated from other elements in igneous mineral such as those above, and is also extracted from the water of mineral springs. The metal is produced electrolytically from a mixture of fused lithium and potassium chloride. In 1998 it was about US$ 43 per pound ($95 per kg).

Chile is currently the leading lithium metal producer in the world, with Argentina next. Both countries recover the lithium from brine pools. In the United States lithium is similarly recovered from brine pools in Nevada.

Isotopes of Lithium

⁶Li [3 neutrons]

Abundance: 7.5%

Stable with 3 neutrons

Lithium-6 is valued as a source material for tritium (an isotope of hydrogen) production and as a neutron absorber in nuclear fusion.

⁷Li [4 neutrons]

Abundance: 92.5%

Stable with 4 neutrons

⁷Li is one of the primordial elements or, more properly, primordial isotopes, produced in Big Bang nucleosynthesis (a small amount of ⁶Li is also produced in stars).

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