Lithium

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This article is about the chemical element lithium. For other uses, see lithium (disambiguation).

3 helium ← lithium → beryllium H ↑ Li ↓ Na Periodic Table - Extended Periodic Table
General
Name, Symbol, Number	lithium, Li, 3
Chemical series	alkali metals
Group, Period, Block	1, 2, s
Appearance	silvery white/grey
Standard atomic weight	6.941(2) g·mol−1
Electron configuration	1s2 2s1
Electrons per shell	2, 1
Physical properties
Phase	solid
Density (near r.t.)	0.534 g·cm−3
Liquid density at m.p.	0.512 g·cm−3
Melting point	453.69 K (180.54 °C, 356.97 °F)
Boiling point	1615 K (1342 °C, 2448 °F)
Critical point	(extrapolated) 3223 K, 67 MPa
Heat of fusion	3.00 kJ·mol−1
Heat of vaporization	147.1 kJ·mol−1
Heat capacity	(25 °C) 24.860 J·mol−1·K−1
Vapor pressure P/Pa 1 10 100 1 k 10 k 100 k at T/K 797 885 995 1144 1337 1610
Atomic properties
Crystal structure	cubic body centered
Oxidation states	1 (strongly basic oxide)
Electronegativity	0.98 (Pauling scale)
Ionization energies	1st: 520.2 kJ/mol
	2nd: 7298.1 kJ/mol
	3rd: 11815.0 kJ/mol
Atomic radius	145 pm
Atomic radius (calc.)	167 pm
Covalent radius	134 pm
Van der Waals radius	182 pm
Miscellaneous
Magnetic ordering	paramagnetic
Electrical resistivity	(20 °C) 92.8Ω·m
Thermal conductivity	(300 K) 84.8 W·m−1·K−1
Thermal expansion	(25 °C) 46 µm·m−1·K−1
Speed of sound (thin rod)	(20 °C) 6000 m/s
Young's modulus	4.9 GPa
Shear modulus	4.2 GPa
Bulk modulus	11 GPa
Mohs hardness	0.6
CAS registry number	7439-93-2
Selected isotopes
Main article: Isotopes of lithium iso NA half-life DM DE (MeV) DP 6Li 7.5% Li is stable with 3 neutrons 7Li 92.5% Li is stable with 4 neutrons 6Li content may be as low as 3.75% in natural samples. 7Li would therefore have a content of up to 96.25%.
References
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Lithium (IPA: /ˈlɪθiəm/, from Greek: lithos: stone, because it was discovered in petalite) is a chemical element with the symbol Li and atomic number 3. It is in group 1 of the periodic table, among the alkali metals and is the lightest solid element.

Lithium in its pure form does not occur naturally on Earth. It is a soft, silver white metal. Lithium reacts with oxygen from the air to form white lithium oxide (Li₂O). It therefore has to be stored under the cover of oil to stop this oxidation reaction from occurring. It tarnishes and oxidizes very rapidly in air and water. Lithium metal is used primarily in heat-transfer applications, batteries (mainly cell phone and camera batteries), household appliances such as toasters and microwaves, and in high performance alloys such as those used for aircraft construction. Lithium compounds are used pharmacologically as a class of mood stabilizing drugs, a neurological effect of the lithium ion Li⁺.

Contents 1 Basic features 2 Occurrence 3 Isotopes 4 History 5 Applications 5.1 Medical Use 5.2 Other uses 6 Market trend 7 Regulation 8 See also 9 References 10 External links

[edit] Basic features

Though in group 1, lithium also exhibits properties of the alkaline-Earth metals in group 2. Like all alkali metals, it has a single valence electron, and will readily lose this electron to become a positive ion. Because of this, lithium reacts easily with water and does not occur as the free element on Earth. Nevertheless, it is less reactive than the chemically similar sodium(Na).

Lithium is soft enough to be cut with a knife, though this is significantly more difficult to do than cutting sodium. The fresh metal is silver in color, rapidly tarnishing black in air. Lithium has only about half the specific gravity of water, giving solid metal lithium sticks the odd heft of a light/medium wood, such as pine. The metal floats highly in hydrocarbons due to its low density, and jars of lithium in the laboratory are typically composed of black-coated sticks held down in hydrocarbon mechanically by the lid of the jar and other sticks.

When placed over a flame, lithium gives off a striking crimson color, but when it burns strongly, the flame becomes a brilliant white. Lithium will ignite and burn when exposed to water and water vapours in oxygen. It is the only metal that reacts with nitrogen at room temperature. Lithium has a high specific heat capacity, 3582 J/(kg·K), and a great temperature range in its liquid form, which makes it a useful chemical.

Lithium metal is flammable and potentially explosive when exposed to air and especially water, though it is far less dangerous than other alkali metals in this regard. The lithium-water reaction at normal temperatures is brisk but not violent. Lithium fires are difficult to extinguish, requiring special chemicals designed to smother them.

Lithium metal, due to its alkaline tarnish, is a corrosive and requires special handling to avoid skin contact. Breathing lithium dust or lithium compounds (which are often alkaline) can irritate the nose and throat; higher exposure to lithium can cause a build-up of fluid in the lungs, leading to pulmonary edema. The metal itself is usually less a handling hazard than the caustic hydroxide produced when it is in contact with moisture. Lithium should be stored in a non-reactive compound such as naphtha or a hydrocarbon.

In humans lithium compounds have not been found to play a natural biological role; large amounts are slightly toxic. Lithium appears to be an essential trace element for goats, and possibly rats, suggesting a role in humans by analogy. However, the essentiality of ultratrace mineral in humans is far more difficult to determine, due to the difficulty and ethical issues involved with the experiments, which involve total isolation from the environment, and unpalatable semi-synthetic foods.

When used as a drug, blood concentrations of Li⁺ must be carefully monitored.

[edit] Occurrence

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, lepidolite, petalite, and amblygonite. 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).^[1].

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.^[2]

See also Lithium minerals.

[edit] Isotopes

Main article: Isotopes of lithium

Naturally occurring lithium is composed of two stable isotopes ⁶Li and ⁷Li, the latter being the more abundant (92.5% natural abundance). Seven radioisotopes have been characterized, the most stable being ⁸Li with a half-life of 838 ms and ⁹Li with a half-life of 178.3 ms. All of the remaining radioactive isotopes have half-lives that are shorter than 8.6 ms. The shortest-lived isotope of lithium is ⁴Li which decays through proton emission and has a half-life of 7.58043x10^-23 s.

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). Lithium isotopes fractionate substantially during a wide variety of natural processes, including mineral formation (chemical precipitation), metabolism, and ion exchange. Lithium ion substitutes for magnesium and iron in octahedral sites in clay minerals, where ⁶Li is preferred to ⁷Li, resulting in enrichment of the light isotope in processes of hyperfiltration and rock alteration.

[edit] History

Petalite, which has lithium in it, was discovered by the Brazilian scientist José Bonifácio 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 Utö in Sweden. In 1818 Christian Gmelin was the first to observe that lithium salts give a bright red color 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" (Greek λιθoς (lithos), meaning "stone") because it was discovered from a mineral while other common alkali metals were first discovered from plant tissue.

[edit] Applications

Because of its specific heat capacity, the highest of all solids, lithium is often used in heat transfer applications.

It is an important battery cathode material, used in lithium ion batteries because of its high electrochemical potential. The lithium ion cell is lighter than a standard dry cell and produces twice the voltage (3 volts rather than 1.5).

Large quantities of lithium are also used in the manufacture of organolithium reagents, especially n-butyllithium which has many uses in fine chemical and polymer synthesis.

[edit] Medical Use

Main article: Lithium pharmacology

Lithium salts such as lithium carbonate (Li₂CO₃), lithium citrate, and lithium orotate are mood stabilizers. 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. It is also sometimes prescribed as a preventive treatment for migraine disease and cluster headaches.

The active principle in these salts is the lithium ion Li⁺, which interacts with the normal function of sodium ions to produce numerous changes in the neurotransmitter activity of the brain. Therapeutically useful amounts of lithium are only slightly lower than toxic amounts, so the blood levels of lithium must be carefully monitored during treatment.

[edit] Other uses

• Lithium chloride and lithium bromide are extremely hygroscopic and frequently used as desiccants.
• Lithium stearate is a common all-purpose high-temperature lubricant.
• Lithium is an alloying agent used to synthesize organic compounds.
• Lithium is used as a flux to promote the fusing of metals during welding and soldering. It also eliminates the forming of oxides during welding by absorbing impurities. This fusing quality is also important as a flux for producing ceramics, enamels, and glass.
• Lithium is sometimes used in glasses and ceramics including the glass for the 200-inch (5.08 m) telescope at Mt. Palomar.
• Alloys of the metal with aluminium, cadmium, copper, and manganese are used to make high performance aircraft parts.
• Lithium niobate is used extensively in telecommunication products, such as mobile phones and optical modulators.
• The high non-linearity of lithium niobate also makes a good choice for non-linear optics applications.
• Lithium deuteride was the fusion fuel of choice in early versions of the hydrogen bomb. When bombarded by neutrons, both ⁶Li and ⁷Li produce tritium. Tritium fuses with deuterium in a fusion reaction that is relatively easy to achieve. Although details remain secret, lithium apparently no longer plays a role in modern nuclear weapons, having been replaced entirely for the purpose by elemental tritium, which is lighter and easier to handle than lithium salts.^{[citation needed]}
• Lithium will be used to produce tritium in magnetically confined nuclear fusion reactors using deuterium and tritium as the fuel. Tritium does not occur naturally and will be produced by surrounding the reacting plasma with a 'blanket' containing lithium where neutrons from the deuterium-tritium reaction in the plasma will react with the lithium to produce more tritium. ⁶Li + n --> ⁴He + ³T. Various means of doing this will be tested at the ITER reactor being built at Cadarache, France.
• Lithium is used as a source for alpha particles, or helium nuclei. When ⁷Li is bombarded by accelerated protons, ⁸Be is formed, which undergoes spontaneous fission to form two alpha particles. This was the first man-made nuclear reaction, produced by Cockroft and Walton in 1929.
• Lithium hydroxide (LiOH) is an important compound of lithium obtained from lithium carbonate (Li₂CO₃). It is a strong base, and when heated with a fat, it produces a lithium soap. Lithium soap has the ability to thicken oils and so is used commercially to manufacture lubricating greases.
• Lithium metal is used as a reducing agent in some types of methamphetamine production, particularly in illegal amateur “meth labs.”
• Lithium hydroxide is an efficient and lightweight purifier of air. In confined areas, such as aboard spacecraft and submarines, the concentration of carbon dioxide can approach unhealthy or toxic levels. Lithium hydroxide absorbs the carbon dioxide from the air by reacting with it to form lithium carbonate. Any alkali hydroxide will absorb CO₂, but lithium hydroxide is preferred, especially in spacecraft applications, because of the low formula weight conferred by the lithium. Even better materials for this purpose include lithium peroxide (Li₂O₂) that, in presence of moisture, not only absorb carbon dioxide to form lithium carbonate, but also release oxygen. E.g. 2 Li₂O₂ + 2 CO₂ --> 2 Li₂CO₃ + O₂.

[edit] Market trend

Prices of lithium carbonate rose by 20% in 2005 and growth of up to 25% is forecast by Roskill Consulting Group for 2006, bringing prices back to the peak levels seen prior to SQM's entry into the market in 1996. New capacity due on-stream in Chile, Argentina and China is forecast to alleviate the upward pressure on prices after 2007.

Consumption of lithium increased by 4–5% per year between 2002 and 2005, driven by demand in lithium secondary batteries. Batteries accounted for 20% of total consumption in 2005, a rise from under 10% in 2000.

Continued expansion in the portable electronic products market and commercialisation of hybrid electric vehicles using lithium batteries suggest growth of up to 10% per year in lithium carbonate consumption in this market through 2010.

Between 2002 and 2005, lithium minerals production rose by 7% per year to reach 18,800 tonnes Li. Chile and Australia account for over 60% of total output. FMC Lithium of the USA, Chemetall of Germany and SQM of Chile continue to dominate production of downstream lithium chemicals.

China may emerge as a significant producer of brine-based lithium carbonate towards the end of this decade. Potential capacity of up to 45,000 tonnes per year could come on-stream if projects in Qinghai province and Tibet proceed.^[3]

[edit] Regulation

Some jurisdictions limit the sale of lithium batteries, which are the most readily available source of lithium metal for ordinary consumers. Lithium can be used to reduce pseudoephedrine and ephedrine to methamphetamine in the Birch reduction method, which employs solutions of alkali metals dissolved in anhydrous ammonia. However, the effectiveness of such restrictions in controlling illegal production of methamphetamine remains indeterminate and controversial.

Carriage and shipment of some kinds of lithium batteries may be prohibited aboard certain types of transportation (particularly aircraft), because of the ability of most types of lithium batteries to fully discharge very rapidly when short-circuited, leading to overheating and possible explosion. However, most consumer lithium batteries have thermal overload protection built-in to prevent this type of incident, or their design inherently limits short-circuit currents.

Lithium is a component for thermonuclear weapons (so called "hydrogen bombs") and applications of lithium for this purpose in the nuclear weapons industry is pursued in developing nuclear powers like India, and presumably others.

[edit] See also

• Lithium compounds

[edit] References

1. ^ A PDF file on lithium prices from the U.S. Geological Survey. Retrieved on September 15, 2005.
2. ^ Los Alamos National Laboratory – Lithium. Retrieved on September 15, 2005.
3. ^ http://www.roskill.com/reports/prePublication/prepublithium

Book references

• Stwertka, Albert (2002). A Guide to the Elements. New York, NY: Oxford University Press. ISBN 0-19-515027-9. 
• Krebs, Robert E. (1998). The History and Use of Our Earth's Chemical Elements : A Reference Guide. Westport, Conn.: Greenwood Press. ISBN 0-313-30123-9. 
• Newton, David E. (1994). The Chemical Elements. New York, NY: Franklin Watts. ISBN 0-531-12501-7. 

[edit] External links

• USGS: Lithium Statistics and Information
• WebElements.com – Lithium
• It's Elemental – Lithium
• Links to external chemical sources
• Safety information on Lithium