The chemical element lithium became famous thanks to the discovery of Johann August Arfvedson in 1817 in the composition of aluminosilicate, petalite. Then the "fire-permanent alkali" was found in other minerals of natural origin. It is a white metal with a silvery sheen that can be cut with a knife. It takes third place in the periodic table and is denoted by Li (from the Latin Lithium).
Brief description of the chemical element Lithium
Ordinal (atomic) number of an element in the periodic system chemical elements Mendeleev is three. Under normal conditions, metallic Li has the lowest density of all known metals. In addition, he leads the alkali metal family for melting and boiling points.
Historical facts
The first metal sample was obtained by Sir Humphrey Davy during the decomposition process electric shock lithium hydroxide melt. Along with the first result of the electrolysis of lithium, Leopold Gmelin, experimenting with lithium-containing salts, noted the coloration of the flame in a dark carmine color.
Lithium chemical properties
Lithium exhibits "capricious" properties when mixed with sodium, does not react at all with melts of potassium, rubidium and cesium. At room temperature, lithium does not interact with dry air or hydrogen. Unlike other alkali metals, it cannot be stored in kerosene. For this purpose, use Sherwood oil, paraffin, gas gasoline or mineral oil in sealed tin containers.
At temperatures above 100, but below 300 degrees Celsius, a protective oxide film forms on the surface of lithium, which prevents further interaction of the chemical. Item with the environmenteven in humid air. The metal form of the element burns when it hits the wet surface of the skin or mucous membrane.
Lithium application
The element itself and its compounds are widely used for the production of glass, as a coating for porcelain. Ferrous and non-ferrous metallurgy use lithium to impart strength and ductility to alloys, and in the manufacture of lubricants. The textile industry uses this element as a bleaching agent for fabrics, the food industry as a preservative, and pharmaceuticals successfully use it in cosmetic preparations.
Liquid lithium has found its use in nuclear reactors, radioactive tritium is obtained using the lithium-6 isotope. The alkali metal is widely used in the chemical industry as a catalyst for many processes, a component of alloys from which cold cathodes are made, as well as anodes of current sources.
Lithium fluoride in the form of single crystals is used to create high-precision lasers with an efficiency of 80%. Various compounds with lithium are involved in flaw detection, pyrotechnics, radio electronics, and optoelectronics.
Lithium salts are a psychotropic substance, the positive effect of which on the mental state of a person was confirmed only in the middle of the 20th century. Lithium carbonate has been successfully used to treat suicidal people with bipolar disorder, manic depression.
This explains the low crime rate in areas where lithium is largely contained in drinking water... The mechanism of action of the element is still poorly understood, but there are suggestions that a positive effect is achieved by the regulatory function of the activity of some of the enzymes involved in the transfer of sodium and potassium ions to the brain. The balance of Na and K is directly responsible for the state of the psyche. It has been proven that in people prone to depression, cells have excess sodium, and lithium evens out the ionic picture.
Lithium's ability to reduce depression and the risk of suicide is reflected in the works of the bands Nirvana and Evanescence. Their discography includes psychedelic songs called Lithium.
The role of lithium in the activation of dormant bone marrow cells is the basis of the hope of modern medicine in the fight against blood cancer. It has been experimentally proven that lithium has a beneficial effect on the affected areas of genital herpes. The use of Li in the treatment of hypertension and diabetes was positively noted. Efficiency in the prevention of sclerosis and diseases of the cardiovascular system is undeniable.
Being present in lubricants, lithium allows the development of Antarctica, in conditions of critically low temperatures. Without this element, the technique will simply fail. It is considered as a component of solid rocket fuel, because the result of combustion of 1 kg of solid Li is more than ten thousand kilocalories, which is almost five times more than the result of combustion of 1 kg of kerosene.
This presentation discusses the characteristics of the chemical element-metal according to the plan: the position in the PSCE, the structure of the atom and its electronic shells, comparing it with those adjacent to the group and period, a simple substance and its compounds: oxides, hydroxides, salts.
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Characteristics of a chemical element-metal on the basis of its position in D.I. Mendeleev's PSHE
Lesson objectives Write an outline general characteristics chem. Element by its position in PSCE Repeat the structure of the atom, types of chemical. communication, classification inorganic substances and their properties in the light of TED and OVR, the genetic relationship between the classes of inorganic substances To acquaint students with the tasks of the reaction product yield
The plan of the characterization of a ChE by its position in the PSCE Address of the ChE Atomic structure, manifested properties, comparison with neighboring elements Physical properties of a simple substance Oxide formed by this ChE and its properties, type and scheme of chem. bonds Hydroxide formed by this CE, its properties, type of bond Hydrogen compound, its properties Salts and their properties
Let us give the characteristics of the LITHIUM element Serial number 3, period 2 (small), group 1, main subgroup (IA) + 3 Metal element Li 0 - 1 e Li + Reducing agent oxidation 2 1 n \u003d 2 n \u003d 1 SS p 1S 2 2 S 1 + S Li.
Let's compare the properties of a lithium atom with neighboring CEs by group and period In the group: Lithium - Sodium On the outer shell - 1 electron each (similarity) The number of shells: sodium has 1 shell more, therefore, the radius of the sodium atom is larger than that of lithium, metallic and the reducing properties of sodium are stronger In the period: Lithium - Beryllium The number of shells - 2 each (similarity) The number of external electrons: lithium has 1 e, and sodium has 2 e, therefore, the radius of the lithium atom is greater than that of beryllium, the metallic and reducing properties of lithium stronger
Lithium - a simple substance Alkali metal silvery, very light, stored under a layer of kerosene, does not occur in nature in free form, crimson flame T pl. \u003d 180.6 0, T bp. \u003d 1342 0, density 0.534 g / s m 3 Metallic crystal lattice Metallic chem. bond Li 0 - 1 e Li + atom ion Electrical conductivity, thermal conductivity, malleability, plasticity, metallic luster, cut with a knife, but quickly oxidizes and darkens on the cut due to its activity Chemical properties: reacts with water and non-metals (oxygen, nitrogen, halogens , hydrogen, etc.) - draw up the reaction equations
Lithium oxide - Li 2 O Salt-forming, basic Ionic bond (write down the bond formation scheme) White color Chemical properties: Write down the reactions of lithium oxide with water, carbon monoxide (IV), hydrochloric acid Obtaining: Li 2 O 2 + 2 Li \u003d 2 Li 2 O lithium peroxide lithium oxide
Lithium hydroxide - LiOH Li + - OH - ionic bond Li + - simple ion, OH - - complex ion OH - - CPS White hygroscopic powder, soapy to the touch, caustic Chemical properties: write down the reactions of lithium hydroxide with sulfuric acid, copper sulfate (II ), carbon monoxide (IV), the exception is decomposition upon heating Obtaining: electrolysis of melts of halogen-containing salts 2 LiCl 2 Li + Cl 2
Hydrogen compound - LiH lithium hydride Solid White Hygroscopic Used as a reductant of C ol lithium Check the solubility of lithium salts in water according to the solubility table
Discovery of lithium A. Arfvedson, 1817 - recognized lithium as a new alkali metal For the first time isolated from the layered silicate mineral petalite LiAlSi 4 O 10 Name - from the Greek "stone" G. Davi, 1818, electrolysis of molten lithium oxide
Genetic series of the metal Recall the signs of the genetic series: One and the same chemical element-metal Different forms of existence of this element-metal (simple substance-oxide-base-salt) Interconversions of substances of different classes
Genetic series of lithium metal Li Li 2 O LiOH LiCl, Li 2 SO 4, LiNO 3 Task: carry out a chain of transformations (compose reaction equations)
Tasks for impurities and the yield of the reaction product Find the volume of carbon dioxide (n.o.) that can be obtained by reacting 250 g of limestone containing 20% \u200b\u200bimpurities with an excess of nitric acid. Can you get the full 100% volume? Find the volume of carbon dioxide if the gas yield is 75% of the theoretically possible.
Remember the formulas! η - product yield m pr. V pr. η \u003d ----- \u003d ------- m theor. V theor.
Homework § 1, exercises Solve the problem. When 800 mg of a 30% sodium hydroxide solution were reacted with an excess of copper sulfate (copper (II) sulfate) solution, 196 mg of precipitate was obtained. What is its output in% of the theoretically possible?
Part I
1. Fill in the table "Characteristics of an element based on its position in the Periodic Table (PS) of DI Mendeleev" using the example of the element calcium.
2. Confirm the nature of calcium oxide with the appropriate reaction equations, including ionic ones, for reactions involving electrolytes:
3. Confirm the nature of calcium hydroxide with the appropriate reaction equations in molecular, full and abbreviated ionic forms:
Part II
1. Cross out "unnecessary".
4) Si
2. Which of the following groups of elements contains only metals?
There is no correct answer.
3. Which of the characteristics of a metal bond is imprecise?
Metal bond:
1) is characterized by non-directionality;
2) is characterized by unsaturation.
4. What physical property is not common to all metals?
3) solid state of aggregation under standard conditions.
5. Characterize the lithium cell according to the outline in Part I.
1) This is an element of the I A group, the 2nd minor period.
2) + 3Li 2e, 1e.
3) Li is a strong reducing agent that is obtained from. about. +1.
4-5) Li is a metal, therefore it has a metallic crystal latticeformed by the metal chemical bond, the scheme of which:
6) allotropy for lithium is not typical.
7) The metallic properties of lithium are more pronounced than that of beryllium.
8) The metallic properties of lithium are more pronounced than that of hydrogen, but less than that of sodium.
9) Lithium oxide has a basic character and interacts:
with acidic oxides;
with acids;
with water.
10) Lithium hydroxide LiOH has a basic character and is a soluble base - alkali. Interacts (write equations possible reactions in molecular, full and abbreviated ionic forms):
6. Metals (M) of the IA group, or alkali metals, form hydrogen compounds with the general formula MH. In these compounds, in contrast to the volatile hydrogen compounds of non-metals, the bond is ionic and the crystal lattice is ionic.
These binary compounds exhibit the following physical properties:
White crystalline substanceslike salt.
7. Metals IIA group (starting with Ca) - alkaline earth metals - form hydrogen compounds with the general formula. They are called hydrides, have an ionic crystal lattice, built by ionic chemical bonds, and have the following physical properties: white, salt-like crystalline substances.
When interacting with water, an exchange reaction is observed.
Performed:
1st year student 2 LD groups
2 medical faculties
Lebed Ekaterina
Zaporizhzhia 2014
1. Characteristics of the element
2. History of the discovery of Lithium
3. Obtaining Lithium
4. Physical and chemical properties of the element
5. The most important compounds of lithium.
6. Application
7. Lithium preparations
Element characteristic
LITHIUM(Latin 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 in the form of two stable nuclides 6Li (7.52% by mass) and 7Li (92.48%). In the periodic system of DI Mendeleev, lithium is located in the second period, group IA and belongs to the number of alkali metals. Configuration of the electron shell of a neutral lithium atom 1 s22s1. 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. Pauling's electronegativity is 0.98, the highest for alkali metals. In the form of a simple substance, lithium is a soft, ductile, light, silvery metal.
The history of the discovery of Lithium
Element No. 3, called lithium (from the Greek "lithos" - stone), was discovered in 1817, when, when he was conducting his famous experiments, an outstanding English scientist Humphrey Davy on the electrolysis of alkaline earths, it was not yet known about the existence of lithium in nature. The lithium earth was discovered only in 1817 by the analytical chemist Arfvedson, a Swede by nationality. In 1800, the Brazilian mineralogist de Andrada e Silva, making a scientific trip to Europe, found in Sweden two new minerals, which he called petalite and spodumene, which was rediscovered on the island of Ute. Arfvedson became interested in petalite. After carrying out a complete qualitative and quantitative analysis, he discovered a loss of about 4% of the substance, which, of course, alerted him and gave rise to the search for the missing substance. He repeated his analyzes more carefully and scrupulously, he found that petalite contains "a fire-resistant alkali of a still unknown nature." Berzelius, whose student Arfvedson was, suggested calling it Lithion, since this alkali, unlike potassium and soda, was first found in the "kingdom of minerals" (stones); the name is derived from the Greek - stone. Arfvedson continued his research and discovered lithium earth, or lithin, and several other minerals. But he failed to isolate this chemical element, he was very active and it was difficult to obtain it. Small masses of metallic lithium were obtained by Davy and Brande by alkali electrolysis. In 1855 g. Bunsen and Mattessen developed an industrial method for producing metallic lithium by electrolysis of lithium chloride. In Russian chemical literature at the beginning of the 19th century. there are names: lithion, lithin (Dvigubsky, 1826) and lithium ( Hess); lithium earth (alkali) was sometimes called lithin.
Lithium is produced in two main stages:
1) obtaining pure lithium chloride;
2) electrolysis of molten lithium chloride.
The most important technical lithium ore is lithium aluminosilicate. The spodumene ore is first concentrated by separating the waste rock from the spodumene mineral.
One of the ways to obtain lithium chloride from spodumene is chlorinating roasting of spodumene in a mixture with CaCO3 and NH4Cl at 750 ° C. As a result, a sinter consisting of lithium chloride, calcium silicate, aluminum oxide, and also potassium, sodium and calcium chlorides is obtained.
The speck is leached cold water, while lithium, potassium and sodium chlorides, as well as a small amount of CaCl2 and Ca (OH) 2, pass into the solution. With industrial air conditioners the required temperature level is maintained in the room. Calcium is transferred to an insoluble state by treating the solution with potash, the precipitate is separated and the pure solution is evaporated until the crystallization of the salts begins. Then dry hydrogen chloride is passed through the solution, as a result of which the solubility of KCl and NaCl sharply decreases and they precipitate, which is separated from the solution. The solution is evaporated, and hydrate LiCl Ho crystallizes from it, which is then dehydrated by heating and then used as a raw material for the electrolytic production of lithium.
There are other methods of decomposition of spodumene (sintering with potassium sulfate or a mixture of limestone with calcium chloride) with subsequent processing of the cakes to obtain lithium chloride from them.
Lithium metal is obtained by electrolysis of lithium chloride at 400-500 ° C. A mixture of LiCl and KCl containing about 60% is used as the electrolyte. The anode and cathode spaces are separated by an iron mesh diaphragm. Above the cathode, there is a receiver for liquid lithium floating on the electrolyte surface. Chlorine is removed through a channel located in the upper ceiling of the cell. Pipes for feeding the bath with molten lithium chloride and extracting liquid metal pass through the same ceiling.
Technological regime and main parameters of electrolysis: anode current density 2.1, cathodic 1.4 a / cm2; voltage on terminals 6-8 V, current output 90%. Consumption per 1 kg of lithium: 6.2 kg LiCl, 0.1-0.2 kg KG, direct current electricity 144-216 kJ.
Raw lithium contains more than 99% Li, the main impurities (Na, K, Mg, Al, Fe, Si) can be removed by refining lithium by sublimation, or by vacuum distillation.