The formula of a simple substance of lithium. Chemical and physical properties of lithium, its reaction with oxygen

Lithium(lat. Lithium; denoted by the symbol Li) - an element of the main subgroup of the first group, the second period periodic system chemical elements of D. I. Mendeleev, with atomic number 3 and atomic mass 6.941. The chemical symbol Li is read in the same way as the name of the element itself. A simple substance lithium is a soft alkali metal silvery white color.

Lithium was discovered in 1817 by the Swedish chemist and mineralogist A. Arfvedson, first in the mineral petalite (Li,Na). The red coloration of the flame characteristic of lithium compounds was first observed by the German chemist H. G. Gmelin in 1818. In the same year, the English chemist G. Davy obtained a piece of metal by electrolysis of a melt of lithium hydroxide. It was only in 1855 that it was possible to obtain free metal in sufficient quantities for the first time only by electrolysis of molten lithium chloride:
2LiCl \u003d 2Li + Cl 2
It got its name due to the fact that it was found in "stones" (Greek lithos - stone). Originally called "lithion". The modern name was proposed by the Swedish chemist Berzelius.

Lithium occurs in nature in the form of two stable nuclides 6 Li (7.52% by weight) and 7 Li (92.48%). Lithium is widely distributed in earth's crust, its content in it is 6.5×10 -3% by weight. As already mentioned, the main minerals containing lithium are petalite (contains 3.5-4.9% Li 2 O), spodumene (6-7% Li 2 O), lepidolite (4-6% Li 2 O) and amblygonite LiAl (8-10% Li 2 O). Lithium is found as an admixture in a number of rock-forming minerals.
Lithium deposits are confined to rare-metal granite intrusions, in connection with which lithium-bearing pegmatites (vein rocks) or hydrothermal complex deposits also containing tin, tungsten, bismuth and other metals. It is worth noting the specific rocks of ongonites - granites with magmatic topaz, high content fluorine and water, and exceptionally high concentrations of various rare elements, including lithium.
Lithium deposits are known in Russia (more than 50% of the country's reserves are concentrated in rare metal deposits Murmansk region), Bolivia (Uyuni salt marsh - the largest in the world), Argentina, Mexico, Afghanistan, Chile, USA, Canada, Brazil, Spain, Sweden, China, Australia, Zimbabwe, Congo.
Another type of lithium deposits is the brines of some highly saline lakes.
Lithium is also present in mineralized waters. AT sea ​​water contains about 2×10 -5% lithium.

As a simple substance lithium is a soft, ductile, light, silvery metal. Of the metals, lithium is the lightest, its density is 0.534 g / cm 3. Melting point 180.5°C, boiling point 1326°C. At temperatures from –193°C to the melting point, the cubic body-centered modification of lithium with the unit cell parameter a = 0.350 nm is stable. Configuration electron shell neutral lithium atom 1s22s1. In compounds, lithium always exhibits an oxidation state of +1. The metal radius of the lithium atom is 0.152 nm, the radius of the Li + ion is 0.078 nm. The sequential ionization energies of the lithium atom are 5.39 and 75.6 eV. The Pauling electronegativity of 0.98 is the highest of the alkali metals.

Due to its small radius and small ionic charge, lithium is most similar in its properties not to other alkali metals, but to the group IIA element magnesium (Mg). Lithium is chemically very active. It is able to interact with oxygen (O) and nitrogen (N) of the air under normal conditions, so it quickly oxidizes in air with the formation of a dark coating of interaction products:
4Li + O 2 \u003d 2Li 2 O,
6Li + N 2 = 2Li 3 N
In contact with halogens, lithium spontaneously ignites under normal conditions. Like magnesium (Mg), heated lithium is able to burn in CO 2:
4Li + CO 2 \u003d C + 2Li 2 O
The standard electrode potential Li/Li+ has the highest negative meaning(E°298 = -3.05 V) compared to standard electrode potentials of other metals. This is due to the high hydration energy of the small Li+ ion, which significantly shifts the equilibrium towards metal ionization:
Li-solid<>Li + solution + e–
For weakly solvating solvents, the value of the electrode potential of lithium corresponds to its lower chemical activity in the series of alkali metals.

Salts are usually colorless crystalline substances. In terms of chemical behavior, lithium salts somewhat resemble analogous magnesium (Mg) or calcium (Ca) compounds. LiF fluoride, carbonate Li 2 CO 3, phosphate Li 2 PO 4 are poorly soluble in water, we will well dissolve lithium chlorate LiClO 3 - this is perhaps one of the most highly soluble compounds in inorganic chemistry(at 18°C ​​313.5 g of LiClO 3 dissolve in 100 g of water).
Lithium oxide Li 2 O - white solid- is a typical alkaline oxide. Li 2 O actively reacts with water to form lithium hydroxide LiOH. This hydroxide is obtained by electrolysis of aqueous solutions of LiCl:
2LiCl + 2H 2 O \u003d 2LiOH + Cl 2 + H 2
LiOH is a strong base, but it differs in properties from other alkali metal hydroxides. Lithium hydroxide is inferior to them in solubility. When calcined, lithium hydroxide loses water:
2LiOH \u003d Li 2 O + H 2 O
Great importance in the synthesis of organic and inorganic compounds has lithium hydride LiH, which is formed by the interaction of molten lithium with hydrogen (H):
2Li + H 2 = 2LiH
LiH is an ionic compound whose crystal lattice structure is similar to that of sodium chloride NaCl. Lithium hydride can be used as a source of hydrogen to fill balloons and rescue equipment ( inflatable boats etc.), since during its hydrolysis, a large number of hydrogen (1 kg LiH gives 2.8 m3 H 2):
LiH + H 2 O \u003d LiOH + H 2
It also finds application in the synthesis of various hydrides, such as lithium borohydride:
BCl 3 + 4LiH = Li + 3LiCl.
Lithium forms compounds with partially covalent bond Li-C, i.e. organolithium compounds. For example, during the reaction of iodobenzene C 6 H 5 I with lithium in organic solvents, the reaction proceeds:
C 6 H 5 I + 2Li = C 6 H 5 Li + LiI.
Organolithium compounds are widely used in organic synthesis and as catalysts.

As mentioned above, lithium was first obtained by electrolysis of molten lithium chloride. At present, to obtain metallic lithium, its natural minerals are either decomposed with sulfuric acid (acid method), or sintered with CaO or CaCO 3 (alkaline method), or treated with K 2 SO 4 (salt method), and then leached with water. In any case, poorly soluble lithium carbonate Li 2 CO 3 is isolated from the resulting solution, which is then converted into LiCl chloride. The electrolysis of the lithium chloride melt is carried out in a mixture with KCl or BaCl 2 (these salts serve to lower the melting point of the mixture). Subsequently, the resulting lithium is purified by vacuum distillation.

Lithium finds very wide application in modern industry.
Thermoelectric materials - an alloy of lithium sulfide and copper sulfide - an effective semiconductor for thermoelectric converters (EMF about 530 μV/K).
Chemical current sources - lithium is used to make anodes of chemical current sources (batteries, for example, lithium-chlorine batteries) and galvanic cells with a solid electrolyte (for example, lithium-chromium-silver, lithium-bismuth, lithium-copper oxide, lithium-manganese dioxide, lithium-iodine lead, lithium -iodine, lithium-thionyl chloride, lithium-vanadium oxide, lithium-fluorocopper, lithium-sulfur dioxide cells) operating on the basis of non-aqueous liquid and solid electrolytes (tetrahydrofuran, propylene carbonate, methyl formate, acetonitrile). Lithium cobaltate and lithium molybdate showed the best operational properties and energy capacity as a positive electrode lithium batteries. Lithium hydroxide is used as one of the components for the preparation of alkaline battery electrolyte. Addition of lithium hydroxide to the electrolyte of traction iron-nickel, nickel-cadmium, nickel-zinc batteries increases their service life by 3 times and capacity by 21% (due to the formation of lithium nickelates).
Lithium aluminate is the most efficient solid electrolyte (along with cesium-beta-alumina).
Laser materials - lithium fluoride single crystals are used to manufacture high-performance (efficiency 80%) lasers based on free color centers, and to manufacture optics with a wide spectral bandwidth.
Oxidizing agents - lithium perchlorate is used as an oxidizing agent.
Defectoscopy - lithium sulfate is used in flaw detection.
Pyrotechnics - Lithium nitrate is used in pyrotechnics.
Alloys - lithium with silver and gold, as well as copper are very effective solders. Alloys of lithium with magnesium, scandium, copper, cadmium and aluminum - new promising materials in aviation and astronautics. On the basis of lithium aluminate and silicate, ceramics have been created that harden when room temperature and used in military equipment, metallurgy, and, in the future, in thermo nuclear power. Glass based on lithium-aluminum-silicate, reinforced with silicon carbide fibers, has tremendous strength. Lithium is very effective in strengthening lead alloys and giving them ductility and corrosion resistance.
Electronics - lithium-cesium triborate is used as an optical material in radio electronics. Crystalline lithium niobate LiNbO 3 and lithium tantalate LiTaO 3 are nonlinear optical materials and are widely used in nonlinear optics, acousto-optics, and optoelectronics. Lithium is also used in the filling of gas-discharge metal halide lamps.
Metallurgy - in ferrous and non-ferrous metallurgy, lithium is used to deoxidize and increase the ductility and strength of alloys. Lithium is sometimes used for the reduction of rare metals by metallothermic methods.
Aluminum metallurgy - lithium carbonate is the most important auxiliary substance (added to the electrolyte) in the smelting of aluminum, and its consumption is growing every year in proportion to the volume of world aluminum production (lithium carbonate consumption is 2.5-3.5 kg per ton of smelted aluminum.
Alloying of aluminum - the introduction of lithium into the alloying system makes it possible to obtain new aluminum alloys with high specific strength. The addition of lithium reduces the density of the alloy and increases the modulus of elasticity. At a lithium content of up to 1.8%, the alloy has a low resistance to stress corrosion, and at 1.9%, the alloy is not prone to stress corrosion cracking. An increase in the lithium content to 2.3% contributes to an increase in the likelihood of formation of looseness and cracks. In this case, the mechanical properties change: the tensile strength and yield strength increase, and the plastic properties decrease. The most well-known alloying systems are Al-Mg-Li (an example is alloy 1420, used for the manufacture of structures aircraft) and Al-Cu-Li (an example is alloy 1460, used for the manufacture of containers for liquefied gases).
Nuclear energy - 6Li and 7Li isotopes have different nuclear properties (thermal neutron absorption cross section, reaction products) and their scope is different. Lithium hafniate is part of a special enamel designed for the disposal of high-level nuclear waste containing plutonium. Lithium-6 (thermonuclear) is used in thermonuclear power engineering. When the nuclide 6Li is irradiated with thermal neutrons, radioactive tritium 3H is obtained. Thanks to this, lithium-6 can be used as a replacement for the radioactive, unstable and inconvenient to handle tritium for both military (thermonuclear weapons) and peaceful (controlled thermonuclear fusion) purposes. In thermonuclear weapons, lithium-6 deuteride 6LiD is commonly used. It is also promising to use lithium-6 to produce helium-3 (through tritium) for further use in deuterium-helium thermonuclear reactors.
Lithium-7 (coolant) - used in nuclear reactors using reactions involving heavy elements such as uranium, thorium or plutonium. Thanks to the very high specific heat and low thermal neutron capture cross section, liquid lithium-7 (often in the form of an alloy with sodium or cesium) serves as an effective coolant. Lithium-7 fluoride in an alloy with beryllium fluoride (66% LiF + 34% BeF2) is called “flybe” (FLiBe) and is used as a highly efficient coolant and solvent for uranium and thorium fluorides in high-temperature liquid-salt reactors, and for the production of tritium.
Gas drying - highly hygroscopic compounds with bromine and chlorine - bromide LiBr and lithium chloride LiCl - are used to dry air and other gases.
Medicine - Lithium salts have normothymic and other medicinal properties. Therefore, they are used in medicine.
Lubricants- Lithium stearate ("lithium soap or lithol") is used as a high temperature lubricant.
Oxygen regeneration in autonomous devices - lithium hydroxide LiOH, peroxide Li 2 O 2 and superoxide LiO 2 are used to purify air from carbon dioxide; while the last two compounds react with the release of oxygen (for example, 4LiO 2 + 2CO 2 → 2Li 2 CO 3 + 3O 2), due to which they are used in insulating gas masks, in cartridges for air purification on submarines, on manned spacecraft, etc. d.
Silicate industry - lithium and its compounds are widely used in the silicate industry for the manufacture of special types of glass and coating of porcelain products.
Other applications - Lithium compounds are used in textile industry(whitening fabrics), food (preservation) and pharmaceutical (cosmetics).

Lithium is present in trace amounts in living organisms, but does not appear to have any biological function. Its stimulating effect on some processes in plants, the ability to increase their resistance to diseases has been established.
The body of an average person (weight 70 kg) contains about 0.7 mg of lithium. Toxic dose 90-200 mg.

Like other alkali metals, lithium metal can cause burns to the skin and mucous membranes, especially in the presence of moisture. Therefore, you can work with him only in protective clothing and glasses. Lithium is stored in a sealed container under a layer mineral oil. Lithium waste should not be thrown into the trash; to destroy it, it should be treated with ethyl alcohol:
2C 2 H 5 OH + 2Li \u003d 2C 2 H 5 OLi + H 2
The resulting lithium ethoxide is then decomposed with water to alcohol and lithium hydroxide LiOH.

Lithium (lat. Lithium; denoted by the symbol Li) is an element of the main subgroup of the first group, the second period of the periodic system of chemical elements of the periodic table, with atomic number 3. The simple substance lithium (CAS number: 7439-93-2) is a soft alkali metal silver -white.

History and origin of the name

Lithium was discovered in 1817 by the Swedish chemist and mineralogist A. Arfvedson, first in the mineral petalite (Li,Na), and then in the spodumene LiAl and in the lepidolite KLi 1.5 Al 1.5 (F,OH) 2 . Lithium metal was first discovered by Humphrey Davy in 1825.
Lithium got its name because it was found in "stones" (Greek λίθος - stone). Originally called "lithion", the modern name was proposed by Berzelius.

Being in nature

Geochemistry of lithium chemical properties refers to large-ion lithophile elements, including potassium, rubidium and cesium. The content of lithium in the upper continental crust is 21 g/t, in sea water 0.17 mg/l.
The main lithium minerals are mica lepidolite - KLi 1.5 Al 1.5 (F, OH) 2 and spodumene pyroxene - LiAl. When lithium does not form independent minerals, it isomorphically replaces potassium in widespread rock-forming minerals.
Lithium deposits are confined to rare-metal granite intrusions, in connection with which lithium-bearing pegmatites or hydrothermal complex deposits, also containing tin, tungsten, bismuth and other metals, develop. It is worth noting the specific rocks of ongonites - granites with magmatic topaz, high content of fluorine and water, and exceptionally high concentrations of various rare elements, including lithium.
Another type of lithium deposits is the brines of some highly saline lakes. Deposits Lithium deposits are known in Russia (more than 50% of the country's reserves are concentrated in rare metal deposits of the Murmansk region), Bolivia, Argentina, Mexico, Afghanistan, Chile, USA, Canada, Brazil, Spain, Sweden, China, Australia, Zimbabwe, Congo.

Receipt

At present, to obtain metallic lithium, its natural minerals are either decomposed with sulfuric acid (acid method), or sintered with CaO or CaCO 3 (alkaline method), or treated with K 2 SO 4 (salt method), and then leached with water. In any case, poorly soluble lithium carbonate Li 2 CO 3 is isolated from the resulting solution, which is then converted into LiCl chloride. The electrolysis of the lithium chloride melt is carried out in a mixture with KCl or BaCl 2 (these salts serve to lower the melting point of the mixture). 2LiCl = 2Li + Cl 2 Subsequently, the resulting lithium is purified by vacuum distillation.

Physical properties

Lithium is a silvery white metal, soft and ductile, harder than sodium but softer than lead. It can be processed by pressing and rolling.
Of all the alkali metals, lithium has the highest melting and boiling points (180.54 and 1340°C, respectively), and the lowest density at room temperature of any metal (0.533 g/cm³, almost half that of water).
The small size of the lithium atom leads to the appearance of special properties of the metal. For example, it is miscible with sodium only at temperatures below 380 ° C and does not mix with molten potassium, rubidium and cesium, while other alkali metal pairs mix with each other in any ratio.

Chemical properties

Lithium is an alkali metal, but relatively stable in air. Lithium is the least active alkali metal; it practically does not react with dry air (and even dry oxygen) at room temperature. For this reason, lithium is the only alkali metal that is not stored in kerosene (besides, the density of lithium is so low that it will float in it) and can be stored in air for a short time.
In humid air, it slowly reacts with nitrogen in the air, turning into Li 3 N nitride, LiOH hydroxide and Li 2 CO 3 carbonate. In oxygen, when heated, it burns, turning into oxide Li 2 O. There is interesting feature that in the temperature range from 100 °C to 300 °C, lithium is covered with a dense oxide film and does not oxidize further.
In 1818, the German chemist Leopold Gmelin found that lithium and its salts color the flame carmine red, which is a qualitative sign for determining lithium. The ignition temperature is about 300 °C. Combustion products irritate the mucous membrane of the nasopharynx.
Calmly, without explosion and ignition, reacts with water, forming LiOH and H 2 . It also reacts with ethyl alcohol (with the formation of an alcoholate), with hydrogen (at 500-700 ° C) with the formation of lithium hydride, with ammonia and with halogens (with iodine - only when heated). At 130 °C, it reacts with sulfur to form sulfide. In a vacuum at temperatures above 200 °C, it reacts with carbon (forming acetylenide). At 600-700 °C, lithium reacts with silicon to form a silicide. Chemically soluble in liquid ammonia (−40 °C), a blue solution forms.
Lithium is stored in petroleum ether, paraffin, gasoline and/or mineral oil in hermetically sealed tins. Lithium metal causes burns when it comes into contact with wet skin, mucous membranes, and eyes.

Lithium (Li) - chemical element with serial number "3" and atomic mass 6.941. occurs in nature as two stable nuclides: 6Li (7.6% by mass) and 7Li (92.4%). In the periodic table of Mendeleev, lithium is located in the second period, the first group. The element belongs to the alkali metals. In compounds, lithium exhibits an oxidation state of +1. In the form of a simple substance, lithium is a ductile, light, silver-colored metal.

Chemical and physical characteristics of lithium

Lithium is the lightest of the metals. It has a density of 0.534 g/cm³. Melts at a temperature of 180.5 °C, boils at a temperature of 1330 °C.

Lithium is very active. Reacts with oxygen and air normal conditions. For this reason, lithium is rapidly oxidized in air with the formation of a dark coating of interaction products. Reaction equations:

4Li + O₂ = 2Li₂O;

6Li + N₂ = 2Li₃N.

The reaction of lithium with oxygen leads to the formation of oxide Li₂O - a colorless crystalline substance with a melting point of 1438 ° C and a boiling point of about 2600 ° C. Lithium oxide is obtained by direct oxidation of metallic lithium at temperatures above 200 ° C, as well as by the decomposition of LiOH hydroxide, LiNO₃ nitrate, LiNO₃ carbonate.

Lithium oxide Li₂O readily reacts with water to form the hydroxide, LiOH. This reaction is accompanied by strong heating; LiOH absorbs CO₂ from the air, forming a carbonate, Li₂CO₃.

The properties of lithium make it possible to use it in science and technology, nuclear power, industry and medicine. The substance is common in many minerals of the earth's crust, in sea water and in the composition of giant stars. Human body also struggle to cope without it. Lithium metal or non-metal? What is its nature and properties? Let's find out.

Lithium - metal or non-metal?

Its name is connected with the Greek word for "stone" and for the first time sounded like "lithion". All due to the fact that it was found in stones or minerals. Until the 19th century, it was not known whether lithium was a metal or a non-metal. No one knew about the existence of such an element until the Swede Johann Avferdson in 1817 discovered an unknown alkali in the minerals spodumene and petalite.

Due to the activity of the substance, the scientist was unable to obtain an element from alkali. But a year later, the Englishman Humphrey Davy did it through electrolysis. After that, it could be studied, and scientific world I was able to find out what lithium is. It turned out that it is a light and soft metal with rather interesting properties.

A quarter of a century later, they learned how to get it industrially and immediately found application for it. Lithium has been used medicinally for headaches, gout, and rheumatism. Although its real benefit in these ailments has not been proven. In the 20th century, a drink with lemon and lime appeared based on lithium carbonate. Now it is known as 7Up, but metal compounds are no longer included in it.

What is he capable of?

Now that we know the metal or non-metal lithium, let's talk about its features. The element lithium with atomic number 3 is usually denoted by the symbol Li. As a simple substance, it has a light silvery color and an extremely small mass. The lightest of all metals on the planet.

It also has the smallest density - only 0.534 g / cm³, which is almost half that of water. Lithium is softer than lead. With a little effort, it can be cut with a knife. It represents a group of alkali metals, in which it has the most high temperature boiling (1339.85 °C) and melting (180.54 0176 °C).

An important characteristic of lithium is its reaction to air. Interacting with oxygen, it oxidizes and becomes covered with a film of oxides, carbonates. It is the only metal that reacts with atmospheric nitrogen at room temperature. At the same time, it is covered with a black coating of lithium nitride. When melting with a temperature of 100 to 300 degrees, it ceases to oxidize immediately after the formation of an oxide film.

The metal reacts relatively calmly with water, releasing hydrogen and lithium hydroxide. If the resulting hydrogen is ignited during the reaction, the metal ions will turn the flame pink-red.

If you just set fire to lithium, then its flame will turn white. But when set on fire in the sand, it will react with silicon and color the fire orange. With gray blue vitriol and wood, lithium burns very actively, exploding or forming many sparks.

In nature

On our planet, lithium is found only in compounds. It is found in sea water in an amount of approximately 0.17 mg / l and in highly saline lakes. It is also contained in the upper layers of the earth's crust in the amount of 21 g/t.

Lithium is mainly found in lepidolites, spodumenes, petalites, lithophilites, amblygonites and zinnwaldites. It occurs together with rare elements in pegmatites and ongonites. It can form independent minerals, and can replace potassium in them.

Metal is also present in space, mainly in giant stars. A huge amount of lithium is in the Thorn-Zhitkov object, which consists of a red giant with a neutron star inside.

Where is it mined

There are lithium deposits on all continents of our planet. They are found in Brazil, Chile, Argentina, Congo, Serbia, China, Australia, USA. The metal itself is not very rare, but in many rocks it is too dispersed, and its extraction is accompanied by great cost and effort.

There are few profitable deposits of lithium. Almost half of the metal deposits remain unused until now. a large share world production is controlled by only three enterprises from Australia, Canada and Zimbabwe. But the largest deposits are in South America.

Approximately 60% of the world's lithium is located in Bolivia on the dried-up Lake Uyuni. This is the largest salt marsh on the planet. Here, among the snow-white salt cover, there are puddles containing great amount metal.

Application

Lithium is not used in pure form because he is too active. As a rule, it is alloyed with other metals, such as sodium. The properties of lithium have found applications in metallurgy - it increases the strength and ductility of alloys. In nuclear power it is used as a coolant. Helium-3 is obtained from the lithium-6 isotope.

The metal is used in the creation of ceramics, glass, rubber and ultrapure metals. They are filled with alkaline batteries and gas-discharge light bulbs. In the textile industry, lithium is used to bleach fabrics; in pharmaceuticals, it is needed for the manufacture of cosmetics.

Biological role

Except environment, lithium is also found in plants and animals. In the human body, it is present in the heart, adrenal glands, blood and plasma, liver, lungs, and thyroid gland. We need it to maintain immunity, protect against allergies and disorders. nervous system, for the exchange of fats and carbohydrates.

A person needs about 100-200 micrograms of lithium per day. It contains potatoes, carrots, lettuce, boletus mushrooms, peaches, radishes, mineral water, meat, fish, eggs, tomatoes, nightshade, etc.

It reduces the excitability of the nervous system, due to which it is often used in medicine. Lithium preparations are prescribed for depression, affective disorders, Alzheimer's disease. But in large quantities metal is harmful to the body. Poisoning them leads to nausea, thirst, decreased libido, dermatitis, dizziness, loss of coordination, and in some cases coma.

Lithium

LITHIUM-I; m.[from Greek. lithos - stone, mineral] Chemical element (Li), soft, very light alkali metal of silver-white color (not found in nature in its pure form).

◁ Lithium, th, th.

(lat. Lithium), a chemical element of group I of the periodic system, belongs to the alkali metals. Name from Greek. líthos - stone (discovered in the mineral petalite). Silvery white, the lightest of the metals; density 0.533 g / cm 3, t pl 180.5°C. Chemically very active, oxidizes at normal temperature; reacts with nitrogen, forming Li 3 N nitride. Minerals - spodumene, lepidolite, etc. The Li isotope is the only industrial source for the production of tritium. Lithium is used for deoxidation, alloying and modification of alloys (for example, aeron, scleron), as a coolant in nuclear reactors, a component of alloys based on Mg and Al, an anode in chemical current sources; some lithium compounds are used in greases, special glasses, heat-resistant ceramics, and are used in medicine.

LITHIUM (lat. Lithium) , Li, chemical element with atomic number 3, atomic mass 6,941. The chemical symbol Li is read in the same way as the name of the element itself.
Lithium occurs naturally as two stable nuclides (cm. NUCLIDE) 6 Li (7.52% by weight) and 7 Li (92.48%). In the periodic system of D. I. Mendeleev, lithium is located in the second period, group IA and belongs to the number of alkali metals (cm. ALKALI METALS). The configuration of the electron shell of the neutral lithium atom 1 s 2 2s one . In compounds, lithium always exhibits an oxidation state of +1.
The metallic radius of the lithium atom is 0.152 nm, the radius of the Li + ion is 0.078 nm. The sequential ionization energies of the lithium atom are 5.39 and 75.6 eV. The Pauling electronegativity is 0.98, the highest of the alkali metals.
In the form of a simple substance, lithium is a soft, ductile, light, silvery metal.
History of discovery and receipt
Lithium was discovered in 1817 by the Swedish chemist and mineralogist A. Arfvedson (cm. ARFVEDSON Johan August) first in the mineral petalite (Li,Na), and then in the spodumene (cm. spodumene) LiAl and in lepidolite (cm. LEPIDOLITH) KLi 1.5 Al 1.5 (F,OH) 2 . It got its name due to the fact that it was found in "stones" (Greek Litos - stone). The red coloration of the flame characteristic of lithium compounds was first observed by the German chemist H.G. Gmelin in 1818. In the same year, the English chemist G. Davy (cm. DEVI Humphrey) electrolysis of a melt of lithium hydroxide obtained a piece of metal. It was possible to obtain free metal in sufficient quantities for the first time only in 1855 by electrolysis of molten chloride:
2LiCl \u003d 2Li + Cl 2
At present, to obtain metallic lithium, its natural minerals are either decomposed with sulfuric acid (acid method), or sintered with CaO or CaCO 3 (alkaline method), or treated with K 2 SO 4 (salt method), and then leached with water. In any case, poorly soluble lithium carbonate Li 2 CO 3 is isolated from the resulting solution, which is then converted into LiCl chloride. The electrolysis of the lithium chloride melt is carried out in a mixture with KCl or BaCl 2 (these salts serve to lower the melting point of the mixture). Subsequently, the resulting lithium is purified by vacuum distillation.
Being in nature
Lithium is quite widespread in the earth's crust, its content in it is 6.5 10 -3% by weight. As already mentioned, the main minerals containing lithium are petalite (contains 3.5-4.9% Li 2 O), spodumene (6-7% Li 2 O), lepidolite (4-6% Li 2, O) and amblygonite (cm. AMBLIGONITE) LiAl - 8-10% Li 2, O. As an impurity, lithium is found in a number of rock-forming minerals, and is also present in the brine of some lakes and in mineralized waters. Sea water contains about 2·10 -5% lithium.
Physical and chemical properties
Of the metals, lithium is the lightest, its density is 0.534 g / cm 3. Melting point 180.5°C, boiling point 1326°C. At temperatures from –193°C to the melting point, the cubic body-centered modification of lithium with the unit cell parameter a=0.350 nm is stable.
Due to its small radius and small ionic charge, lithium in its properties most closely resembles not other alkali metals, but an element of group IIA magnesium (cm. MAGNESIUM). Lithium is chemically very active. It is able to interact with oxygen and nitrogen in the air under normal conditions, so it quickly oxidizes in air with the formation of a dark coating of interaction products:
4Li + O 2 \u003d 2Li 2 O,
6Li + N 2 = 2Li 3 N
In contact with halogens, lithium spontaneously ignites under normal conditions. Like magnesium, heated lithium is able to burn in CO 2:
4Li + CO 2 \u003d C + 2Li 2 O
The standard electrode potential of Li/Li + has the largest negative value (E° 298 = –3.05 V) compared to the standard electrode potentials of other metals. This is due to the high hydration energy of the small Li + ion, which significantly shifts the equilibrium towards metal ionization:
Li solid Li + solution + e –
For weakly solvating solvents, the value of the electrode potential of lithium corresponds to its lower chemical activity in the series of alkali metals.
Lithium compounds - salts - are usually colorless crystalline substances. In terms of chemical behavior, lithium salts somewhat resemble analogous compounds of magnesium or calcium. LiF fluoride, Li 2 CO 3 carbonate, Li 2 PO 4 phosphate are poorly soluble in water, we will well dissolve lithium chlorate LiClO 3 - this is perhaps one of the most highly soluble compounds in inorganic chemistry (at 18 ° C 313 dissolves in 100 g of water .5 g LiClO 3).
Lithium oxide Li 2 O, a white solid, is a typical alkaline oxide. Li 2 O actively reacts with water to form lithium hydroxide LiOH.
This hydroxide is obtained by electrolysis of aqueous solutions of LiCl:
2LiCl + 2H 2 O \u003d 2LiOH + Cl 2 + H 2
LiOH is a strong base, but it differs in properties from other alkali metal hydroxides. Lithium hydroxide is inferior to them in solubility. When calcined, lithium hydroxide loses water:
2LiOH \u003d Li 2 O + H 2 O
Of great importance in the synthesis of organic and inorganic compounds is lithium hydride LiH, which is formed by the interaction of molten lithium with hydrogen:
2Li + H 2 = 2LiH
LiH is an ionic compound whose crystal lattice structure is similar to that of sodium chloride NaCl. Lithium hydride can be used as a source of hydrogen for filling balloons and rescue equipment (inflatable boats, etc.), since its hydrolysis produces a large amount of hydrogen (1 kg of LiH gives 2.8 m 3 H 2):
LiH + H 2 O \u003d LiOH + H 2
It also finds application in the synthesis of various hydrides, such as lithium borohydride:
BCl 3 + 4LiH = Li + 3LiCl.
Lithium forms compounds with a partially covalent Li-C bond, i.e., organolithium compounds. For example, during the reaction of iodobenzene C 6 H 5 I with lithium in organic solvents, the reaction proceeds:
C 6 H 5 I + 2Li = C 6 H 5 Li + LiI.
Organolithium compounds are widely used in organic synthesis and as catalysts.
Application
Lithium is used to make anodes for chemical current sources operating on the basis of non-aqueous solid electrolytes. Liquid lithium can serve as a coolant in nuclear reactors. Using the nuclide 6 Li, radioactive tritium 3 1 H (T) is obtained:
6 3 Li + 1 0 n= 3 1 H + 4 2 He.
Lithium and its compounds are widely used in the silicate industry for the manufacture of special types of glass and coating of porcelain products, in ferrous and non-ferrous metallurgy (for deoxidation, increasing the plasticity and strength of alloys), and for the production of greases. Lithium compounds are used in the textile industry (bleaching fabrics), food (preservation) and pharmaceuticals (cosmetics).
Biological role
Lithium is present in trace amounts in living organisms, but does not appear to have any biological function. Its stimulating effect on some processes in plants, the ability to increase their resistance to diseases has been established.
The body of an average person (weight 70 kg) contains about 0.7 mg of lithium. Toxic dose 90-200 mg.
Features of handling lithium
Like other alkali metals, lithium metal can cause burns to the skin and mucous membranes, especially in the presence of moisture. Therefore, you can work with him only in protective clothing and glasses. Lithium is stored in a sealed container under a layer of mineral oil. Lithium waste should not be thrown into the trash; to destroy it, it should be treated with ethyl alcohol:
2C 2 H 5 OH + 2Li \u003d 2C 2 H 5 OLi + H 2
The resulting lithium ethoxide is then decomposed with water to alcohol and lithium hydroxide LiOH.

encyclopedic Dictionary. 2009 .

See what "lithium" is in other dictionaries:

- (lat. lithium, from the Greek. lithos stone). White metal, discovered in 1817 in petalite; All salts are soluble in water. Dictionary foreign words included in the Russian language. Chudinov A.N., 1910. Lithium is a white metal, the lightest of all, ... ... Dictionary of foreign words of the Russian language

- (Lithium), Li, a chemical element of group I of the periodic system, atomic number 3, atomic mass 6.941; refers to alkali metals, mp 180.54shC. Lithium is used to make anodes for chemical current sources, in the production of copper, ... ... Modern Encyclopedia

Lithium- (Lithium), Li, a chemical element of group I of the periodic system, atomic number 3, atomic mass 6.941; refers to alkali metals, mp 180.54°C. Lithium is used to make anodes for chemical current sources, in the production of copper, ... ... Illustrated encyclopedic Dictionary

- (lat. Lithium) Li, a chemical element of group I of the periodic system, atomic number 3, atomic mass 6.941, belongs to alkali metals. Name from Greek. lithos stone (discovered in the mineral petalite). Silvery white, the lightest of metals; ... ... Big Encyclopedic Dictionary

Li (from Greek lithos stone * a. lithium; n. Lithium; f. lithium; and. litio), chem. element of group I periodic. Mendeleev systems, at. n. 3, at. m. 6.941, refers to alkali metals. In nature, there are 2 stable isotopes: 6Li (7.42%) ... Geological Encyclopedia

LITHIUM- LITHIUM, chem. element, symbol Li, orders. number 3, silvery white metal, at. in. 6.940 (isotopes 6 and 7), t° pl. 186°; belongs to the alkaline group. metals, has the smallest in comparison. with other metals in. (0.59). Discovered by Arphedzon ... ... Big Medical Encyclopedia

LITHIUM- chem. element, symbol Li (lat. Lithium), at. n. 3, at. m. 6.941; silvery white, the lightest metal, belongs to the alkali metals, density 534 kg/m3, tmelt = 180.5°C; easily cut with a knife. L. is chemically very active, interacts with water and ... Great Polytechnic Encyclopedia

- (symbol Li), a rare silver-colored element, one of the alkali metals, was first discovered in 1817. It is contained in such ores as lepidolite and spodumene. It is similar in chemical properties to sodium. The lightest of all metals, used in ... ... Scientific and technical encyclopedic dictionary