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Lithium

2007 Schools Wikipedia Selection. Related subjects: Chemical elements


                 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
                                               Atomic mass 6.941 (2) g/mol
                                          Electron configuration 1s^2 2s^1
                                                  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

   CAPTION: 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 nonmagnetic
                               Electrical resistivity (20 °C) 92.8 nΩ·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

                 CAPTION: 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

   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. Lithium is one of only four elements theorized to have
   been created in the first three minutes of the universe through a
   process called Big Bang nucleosynthesis. 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 black lithium oxide (Li[2]O). 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^+.

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.

   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 colour, 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 very light wood, such as balsa. 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 colour,
   but when it burns strongly, the flame becomes a brilliant white.
   Lithium will ignite and burn when exposed to water and water vapors 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 is a corrosive and requires special handling to avoid
   skin contact. 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 apparently play no natural biological role,
   and are considered to be slightly toxic. Humans aside, lithium appears
   to be an essential trace element for goats, and possibly rats. When
   used as a drug, blood concentrations of Li^+ must be carefully
   monitored.

Occurrence

   Lithium pellets (covered in white lithium hydroxide)
   Enlarge
   Lithium pellets (covered in white lithium hydroxide)

   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). 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

   Naturally occurring lithium is composed of 2 stable isotopes ^6Li and
   ^7Li with ^7Li being the most abundant (92.5% natural abundance). Seven
   radioisotopes have been characterized with 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-lifes that are less
   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 over ^7Li, resulting in enrichment of
   the light isotope in processes of hyperfiltration and rock alteration.

   An interesting isotope is the extremely unstable ^11Li , that exhibits
   a Nuclear halo of two neutrons.

History

   Petalite, which contains lithium, was first discovered by the Brazilian
   scientist José Bonifácio de Andrade e Silva toward the end of the 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(Si[2]O[5])[2], 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 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. 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.

Applications

   Because of its specific heat capacity, the largest of any solid,
   lithium is used in heat transfer applications. It is also an important
   battery anode material, used in lithium ion batteries due to its high
   electrochemical potential. In addition to being lighter than the
   standard dry cell, these batteries produce a higher voltage (3 volts
   versus 1.5 volts). Large quantities of lithium are used in the
   manufacture of organolithium reagents, especially n-butyllithium which
   has many uses in fine chemical and polymer synthesis.

Medical Use

   Lithium salts such as lithium carbonate (Li[2]CO[3]), 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 ion 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 such
   treatment.

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.
     * 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 (Li[2]CO[3]). 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 catalyst 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 CO[2], 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 (Li[2]O[2]) and lithium superoxide
       (LiO[2]) that, in presence of moisture, not only absorb carbon
       dioxide to form lithium carbonate, also release oxygen. E.g. 4
       LiO[2] + 2CO[2] --> 2Li[2]CO[3] + 3 O[2].

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.

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.

   Retrieved from " http://en.wikipedia.org/wiki/Lithium"
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