Clean calcium. Natural calcium compounds

Calcium is known to man from ancient times in the form of alkaline compounds, such as chalk or limestone. In its pure form, this element was obtained at the beginning of the 19th century. Then it was found that according to its basic properties, calcium refers to alkaline metals.

Calcium plays an important biological role - it is the main component of the skeleton macroelectric (including outer) in most species on the planet, is part of the hormones, is a regulator of neural and muscle interactions. Chemically pure calcium is used in various reactions, in metallurgy and in many other industries.

general characteristics

Calcium is one of the typical representatives of the family of active alkali metal. In its pure form, iron is reminded of iron, with a less pronounced gloss. Fragile, breaks with the formation of inhomogeneous crystalline granules. The most calcium is known in the form of its compounds (chalk, limestone, silica and others), where it has the form of a whitish crumbling substance.

In its pure form, it does not occur due to its high reaction activity. Part of the majority of minerals, among which the greatest value They have marble, granite, alabaster and some other valuable breeds.

Basic physico-chemical properties

Refers to the second group periodic system elements showing similar physical properties with other alkaline group representatives:

• Relatively low density (1.6g / cm 3);
• The melting point limit is 840 0 s under normal conditions;
• The average thermal conductivity is generally noticeably lower than in most metals;

In general, calcium physics does not represent special surprises. Possessing a typical crystal grille, this element has a rather low strength and almost zero plasticity, it will easily crumble and is cleaned with the formation of a characteristic crystalline pattern on the border of the break.

Nevertheless, recent studies have shown very interesting results. It has been established that with high atmospheric pressure, the physical properties of the element begin to change. Semiconductor properties are manifested, absolutely uncharacteristic for any metals. Extreme pressure leads to the appearance and calcium of superconducting properties. These studies have far-reaching consequences, but so far the scope of calcium is limited by its usual properties.

In its chemical qualities of the same calcium, no particular is distinguished and is a typical alkaline earth metal:

• High reaction activity;
• Okhotny interaction with the atmosphere and the formation of a characteristic dull film on the surface of the element;
• Actively interacts with water, but, in contrast to such elements, as sodium, the explosive exothermic reaction does not occur;
• Reacts with all active non-metals, including iodine and bromine;

In contrast to more active alkali metal, for reaction with metals and relatively inert elements (for example, with carbon) calcium requires a catalyst or strong heating. Calcium is stored in tightly blocked glass containers, to prevent spontaneous reactions.

Calcium enters the five most common substances on the planet, yielding only oxygen, silicon and aluminum with iron. At the same time, in nature, this element is found mainly in the form of solid or bulk minerals. The most famous calcium connection is limestone. Also, calcium forms a wide range of different minerals, from the above-mentioned granite and marble, to less common barites and spastes. According to exemplary estimates of researchers, calcium content in pure equivalent - about 3.4% by weight.

Sphere of industrial application

In the industrial sector of calcium enters a group of widely demanded materials for metallurgy purposes. With it, purified metals are obtained, including uranium and thorium, as well as some rare-earth elements. The addition of calcium into steel melts contributes to the binding and removal of free oxygen, which improves the structural qualities of the metal alloy. Calcium is also used as an electrolytic element as part of batteries and batteries.

Calcium

CALCIUM -I; m. [from lat. Calx (Calcis) - Lime] Chemical element (CA), silver-white metal, which is included in limestone, marble, etc.

◁ Calcium, and ,y. Both salts.

calcium

(Lat. Calcium), the chemical element II of the group of the periodic system, refers to the pitch-earth metals. Name from lat. Calx, Page Calcis Padge - Lime. Silver-white metal, density 1.54 g / cm 3, t. PL 842ºC. At normal temperature is easily oxidized in air. In the prevalence of B. earth Kore It takes the 5th place (calcite minerals, gypsum, fluorite, etc.). As an active reducing agent serves to obtain u, th, v, cr, zn, bes and other metals from their compounds, for deoxidation of steels, bronze, etc. is included in the composition of antifriction materials. Calcia compounds are used in construction (lime, cement), calcium preparations in medicine.

CALCIUM

Calcium (lat. Calcium), Ca (read "Calcium"), a chemical element with atomic number 20, located in the fourth period in the group IIA of the periodic system of Mendeleev elements; Atomic weight 40.08. Refers to the number of alkaline earth elements (cm. Alkaline earth metals).
Natural calcium consists of a mixture of nuclides (cm. Nuclide) With mass numbers 40 (in mixtures by weight of 96.94%), 44 (2.09%), 42 (0.667%), 48 (0.187%), 43 (0.135%) and 46 (0.003%). Configuration of the external electronic layer 4 s. 2 . Almost in all compounds, the degree of calcium oxidation is +2 (valence II).
Radius of the neutral calcium atom 0.1974 nm, the radius of the ion of Ca 2+ from 0.114 nm (for a coordination number 6) to 0.148 nm (for a coordination number 12). The energy of successive ionization of the neutral calcium atom is equal, respectively, 6,133, 11.872, 50.91, 67.27 and 84.5 eV. On the poling scale, calcium electronence is about 1.0. In the free form of calcium - silver-white metal.
History opening
Calcium compounds occur in nature everywhere, so humanity is familiar with them from ancient times. Has long been in construction found the use of lime (cm. LIME) (Negane and harated), which was considered for a long time simple substance, "Earth". However, in 1808 English scientist Davy (cm. Davy Gemphri) I managed to get a new metal from the lime. For this, Davy subjected the electrolysis of the mixture slightly moistened to hated lime with the oxide of mercury and allocated the new metal from the amalgam at the mercury cathode, which he called calcium (from lat. Calx, bodies. Calcis case - lime). In Russia, for some time this metal was called "limescale".
Finding in nature
Calcium is one of the most common elements on Earth. It accounts for 3.38% of the mass of the earth's crust (5th place in prevalence after oxygen, silicon, aluminum and iron). Due to the high chemical activity of calcium in free form in nature, it is not found. Most calcium is contained as part of silicates (cm. Silicates) and aluminosilicatov (cm. Aluminosilicates) Different rocks (granites (cm. GRANITE), Gneus (cm. GNEISS) etc.). In the form of sedimentary calcium compounds are represented by chalk and limestones consisting mainly of calcite mineral (cm. CALCITE) (CACO 3). Crystalline form of calcite - marble - occurs in nature much less often.
Calcium minerals are quite widespread as limestone (cm. LIMESTONE) Saco 3, Anhydrite (cm. ANHYDRITE) Caso 4 and Gypsum (cm. GYPSUM) Caso 4 · 2H 2 O, Fluoritis (cm. Fluorite) CAF 2, Apatity (cm. Apatity) Ca 5 (PO 4) 3 (F, CL, OH), dolomite (cm. DOLOMITE) Mgco 3 · CaO 3. The presence of calcium and magnesium salts in natural water is determined by its rigidity (cm. HARDNESS OF WATER). A significant amount of calcium is included in living organisms. Thus, hydroxylapatite Ca 5 (PO 4) 3 (OH), or, in another record, 3CA 3 (PO 4) 2 · Ca (OH) 2 - the base of the bone fabric of vertebrates, including a person; Caco 3 calcium carbonate consists of sinks and shells of many invertebrates, egg shell, etc.
Obtaining
Metal calcium is obtained by the electrolysis of the melt consisting of CaCl 2 (75-80%) and KCl or from CaCl 2 and CAF 2, as well as the aluminothermic recovery of Cao at 1170-1200 ° C:
4CaO + 2Al \u003d Caal 2 O 4 + 3CA.
Physical and chemical properties
Metal calcium exists in two allotropic modifications (see Allhotropia (cm. ALLOTROPY)). Up to 443 ° C Resistant a-Ca with a cubic grazent grid (parameter A \u003d 0.558 nm), above stable B-Ca with a cubic volume-centered A-FE type grid (parameter a \u003d 0.448 nm). Calcium melting point 839 ° C, boiling point 1484 ° C, density 1.55 g / cm 3.
The chemical activity of calcium is high, but lower than all other alkaline earth metals. It easily interacts with oxygen, carbon dioxide and air moisture, which is why the metal calcium surface is usually grain, therefore, the calcium laboratory is usually stored, like other alkaline earth metals, in a tightly closed can under the kerosene layer.
In the number of standard calcium potentials is located to the left of hydrogen. The standard electrode potential of the CA 2+ / CA 0.84 V pair, so calcium actively reacts with water:
CA + 2H 2 O \u003d Ca (OH) 2 + H 2.
With active non-metals (oxygen, chlorine, bromine), calcium reacts under normal conditions:
2s + o 2 \u003d 2SAO; CA + BR 2 \u003d CABR 2.
When heated in air or in calcium oxygen is flammable. With less active non-metals (hydrogen, boron, carbon, silicon, nitrogen, phosphorus, and other), calcium enters into interaction when heated, for example:
Sa + n 2 \u003d San 2 (calcium hydride),
CA + 6B \u003d CAB 6 (Boride Calcium),
3CA + N 2 \u003d Ca 3 N 2 (calcium nitride)
CA + 2C \u003d CAC 2 (calcium carbide)
3 to + 2p \u003d Ca 3 P 2 (Calcium phosphide), also known phosphides Calcium compositions of SAR and SAR 5;
2CA + Si \u003d Ca 2 Si (calcium silicide) are also known calcium calcium silicides, Ca 3 Si 4 and Casi 2.
The flow of the above reactions is usually accompanied by the release of a large amount of heat (i.e., these reactions are exothermic). In all connections with non-metals, the degree of calcium oxidation is +2. Most of the calcium compounds with non-metals are easily decomposed with water, for example:
San 2 + 2n 2 o \u003d sa (it) 2 + 2N 2,
Ca 3 N 2 + 3H 2 O \u003d 3A (OH) 2 + 2NH 3.
Calcium oxide is typically main. In the laboratory and technique it is obtained by thermal decomposition of carbonates:
Caco 3 \u003d Cao + CO 2.
The technical oxide of calcium CAO is called negated lime.
It reacts with water with the formation of Ca (OH) 2 and the highlight of a large amount of heat:
CAO + H 2 O \u003d CA (OH) 2.
Obtained by this method Ca (OH) 2 is usually called hawed lime or lime milk (cm. Lime milk) Due to the fact that the solubility of calcium hydroxide in water is small (0.02 mol / l at 20 ° C), and when it is added to the water, a white suspension is formed.
When interacting with acid oxides, CaO forms salts, for example:
CAO + CO 2 \u003d CASSO 3; Sao + SO 3 \u003d Caso 4.
Ion Ca 2+ Babelessly. When installing calcium salts, the flame is painted in brick-red.
Such calcium salts such as CaCl 2 chloride, CABR 2 bromide, CAI 2 iodide and Ca nitrate (NO 3) 2 are well soluble in water. Insoluble in water fluoride CAF 2, CACO 3 carbonate, Caso 4 sulfate, medium orthophosphate Ca 3 (PO 4) 2, CAC 2 oxalate and some others.
The factory is important that, in contrast to the average calcium carbonate CASSO 3, acid calcium carbonate (hydrocarbonate) Ca (NSO 3) 2 in water is soluble. In nature, this leads to the following processes. When cool rain or river water, saturated with carbon dioxide, penetrates under the ground and falls on limestone, then their dissolution is observed:
Saso 3 + CO 2 + H 2 O \u003d CA (NSO 3) 2.
In the same places where the water saturated with calcium bicarbonate goes to the surface of the Earth and heated by the solar rays, the reverse reaction flows:
Ca (NSO 3) 2 \u003d Saso 3 + CO 2 + H 2 O.
So in nature the transfer of large masses. As a result, huge failures may form underground (see Cars (cm. Karst (Phenomenon of Nature))), and in the caves there are beautiful stone "icicles" - stalactites (cm. Stalactites (Mineral Education)) and stalagmites (cm. Stalagmites).
The presence of a dissolved calcium bicarbonate in water largely determines the time rigidity of water (cm. HARDNESS OF WATER). It is called it because, when boiling water, the bicarbonate decomposes, and the precipitate falls out Saco 3. This phenomenon leads, for example, to the fact that in the teapot, scale is formed.
Use of calcium and its connections
Metal calcium is used for metal uranium production (cm. Uranium (chemical element)), thorium (cm. THORIUM), Titan (cm. Titanium (chemical element)), Zirconia (cm. ZIRCONIUM), Cezia (cm. CESIUM) And Rubidia (cm. RUBIDIUM).
Natural calcium compounds are widely used in the production of binding materials (cement (cm. CEMENT), Gypsum (cm. GYPSUM), Lime, etc.). The binding effect of hawed lime is based on the fact that over time calcium hydroxide reacts with carbon dioxide air. As a result of the flowing reaction, needle crystals of Caccite \u200b\u200bCASSO Z are formed, which germinate in the stones located nearby, bricks, other building materials and how to weld them into a one. Crystal calcium carbonate - marble - excellent finishing material. Mel is used for bliss. Large quantities of limestone are spent in the production of cast iron, as they allow you to transfer refractory impurities iron Ore (for example, Quartz SiO 2) into relatively low-melting slags.
Chlorine lime is very effective as a disinfectant (cm. BLEACHING POWDER) - "Chlorine" Ca (OCL) CL - mixed chloride and calcium hypochloride (cm. Calcium hypochlorite)High oxidative.
Calcium sulfate existing both in the form of anhydrous compound and crystallohydrates - the so-called "semi-water" sulfate - alabaster is widely used. (cm. Aleviz Fryazin (Milanic)) Caso 4 · 0,5H 2 O and two-wheel sulfate - CASO 4 · 2H 2 O. Gypsum. Gypsum is widely used in construction, in sculpture, for the manufacture of stucco and various articles. Apply gypsum and medicine for fixing bones during fractures.
CACL 2 calcium chloride is used along with cook Sali. To combat the glaciation of road surfaces. Calcium fluoride Saf 2 is an excellent optical material.
Calcium in the body
Calcium - biogenic element (cm. Biogenic elements), permanently present in plants and animal tissues. An important component of the mineral exchanging of animals and human and mineral nutrition of plants, calcium performs a variety of functions in the body. As part of Apatita (cm. APATITE), as well as sulfate and calcium carbonate forms the mineral component of bone tissue. In the human body weighing 70 kg contains about 1 kg of calcium. Calcium participates in the work of ion channels (cm. Ion channels)transporting substances through biological membranes in transmission nervous impulse (cm. Nervous impulse), in blood coagulation processes (cm. Blood coagulation) and fertilization. Control calcium exchange in the body of calciferols (cm. Calciferols) (Vitamin D). The disadvantage or excess of calcium leads to various diseases - Rakhita (cm. RICKETS), calcine (cm. Calcification) et al. Therefore, human food should contain calcium compounds in the right amounts (800-1500 mg calcium per day). Calcium content is high in dairy products (such as cottage cheese, cheese, milk), in some vegetables and other food products. Calcium preparations are widely used in medicine.

encyclopedic Dictionary. 2009 .

Synonyms:

Calcium (Latin Calcium), CA, chemical element II group of short form (2nd group of long form) of the periodic system; refers to tick-earth metals; Atomic number 20; Atomic weight 40.078. In nature, there are 6 stable isotopes: 40 sa (96.941%), 42 sa (0.647%), 43 sa (0.135%), 44 CA (2.086%), 46 sa (0.004%), 48 sa (0.187%); Artificially obtained radioisotopes with mass numbers 34-54.

Historical reference. Many natural calcium compounds were known in ancient times and widely used in construction (for example, plaster, lime, marble). Metal calcium was first isolated by the city of Davy in 1808 with the electrolysis of the SAO and HGO oxide mixtures and the subsequent decomposition of calcium amalgam formed. The name comes from the Latin Calx (Page Calcis Padge) - Lime, Soft Stone.

Welcome in nature. Calcium content in the earth's crust is 3.38% by weight. Due to high chemical activity in free state, it is not found. The most common minerals Helmet CA, Angidite Caso 4, Apatite CA 5 (PO 4) 3 (F, CL, OH), Caso 4 · 2N 2 O, Calcite and Aragonitis SASI 3, Perovskite Catio 3, Fluorite CAF 2, Sweet Cawo four . Calcium minerals are part of sediment (for example, limestone), magmatic and metamorphic rocks. Calcium compounds are contained in living organisms: are the main components of vertebrate bone tissues (hydroxyapatite, fluoropatite), coral skeletons, molluscs (carbonate and phosphates and calcium phosphates) and others. The presence of Ca 2+ ions determines the rigidity of water.

Properties. Configuration of the outer electronic shell of the 4S 2 calcium atom; In the compounds shows the degree of oxidation +2, rarely +1; Electricity by Paulonga 1.00, atomic radius 180 PM, radius of ion Ca 2+ 114 PM (coordination number 6). Calcium - silver-white soft metal; up to 443 ° C is a stable modification with a cubic grazent crystalline lattice, above 443 ° C - with a cubic volume-centered lattice; T pl 842 ° C, T Kip 1484 ° C, density 1550 kg / m 3; thermal conductivity 125.6 W / (M · K).

Calcium is a metal of high chemical activity (stored in hermetically closed vessels or under the layer of mineral oil). Under normal conditions, it easily interacts with oxygen (calcium SAO oxide is formed), when heated with hydrogen (hydride San 2), halogens (calcium halides), boron (Boride Sav 6), carbon (calcium CA carbide 2), silicon (CA silicides 2 Si, Casi, Casi 2, Ca 3 Si 4), nitrogen (Ca 3 n 2 nitride), phosphorus (Ca 3 P 2, SAR, SAR 5), chalcogen groups (chalcogenides of the composition of CAH, where X - S, SE, Those). Calcium interacts with other metals (Li, Cu, Ag, Au, Mg, Zn, Al, Pb, Sn, etc.) with the formation of intermetallides. Metal calcium interacts with water to form calcium hydroxide Ca (OH) 2 and H 2. Energetically interacts with most acids, forming appropriate salts (for example, calcium nitrate, calcium sulfate, calcium phosphates). It dissolves in liquid ammonia to form a dark-blue solution with metal conductivity. When evaporation of ammonia from such a solution, ammonia is allocated. Gradually, calcium interacts with ammonia to form an amide Ca (NH 2) 2. Forms various complex compounds, complexes with oxygen-containing polydentate ligands have the greatest importance, for example, CA complexons.

Biological role. Calcium refers to biogenic elements. The daily need of a person in calcium is about 1 g. In living organisms, calcium ions are involved in muscle contraction processes, transmission of nerve impulses.

Obtaining. Metal calcium is obtained by electrolytic and metal thermal methods. The electrolytic method is based on the electrolysis of molten calcium chloride with the touch cathode or liquid copper-calcium cathode. From the resulting copper-calcium alloy, calcium is distilled off at a temperature of 1000-1080 ° C and a pressure of 13-20 kPa. Metalothermic method is based on the reduction of calcium from its oxide aluminum or silicon at 1100-1200 ° C. This produces aluminate or calcium silicate, as well as calcium gas, which is then condensed. World production of calcium compounds and materials containing calcium, about 1 billion tons / year (1998).

Application. Calcium is used as a reducing agent when obtaining many metals (Rb, CS, ZR, HF, V, etc.). Calcium silicides, as well as calcium alloys with sodium, zinc and other metals are used as deoxidizers and desulfurators of some alloys and oil, to clean the argon from oxygen and nitrogen, in electrical accumulable devices as a gases absorber. Sasl 2 chloride is used as a dryer in chemical synthesis, gypsum is used in medicine. Calcium silicates are the main components of cement.

Lit.: Rodyakin V. V. Calcium, its compounds and alloys. M., 1967; Spitsyn V. I., Martynenko L. I. Not organic chemistry. M., 1994. Part 2; Inorganic chemistry / Edited by Yu. D. Tretyakova. M., 2004. T. 2.

L. N. Commissioner, M. A. Ryumin.

The bone skeleton is complicated from it, but the body is not able to produce an element independently. Speech about calcium. Adult women and men per day must be obtained at least 800m milligrams of alkaline earth metal. It is possible to remove it from oatmeal, hazelnut, milk, barley cereals, sour cream, beans, almonds.

Calciumcontained in the pea, mustard, cottage cheese. True, if you combine them with sweets, coffee, cola and products, rich oxalic acid, the digestibility of the element falls.

The gastric medium becomes alkaline, calcium is captured in insoluble and derived from the body. Bones and teeth begin to collapse. What is this in the element, since it became one of the most important things for living beings and is there a substance use outside of their organisms?

Chemical and physical properties of calcium

In the periodic system, the element takes the 20th place. It is located in the main subgroup of the 2nd group. The period to which the calcium belongs is 4th. This means that a substance atom has 4 electronic levels. They are 20 electrons on them, which indicates the atomic number of the element. He also testifies to his charge - +20.

Calcium in the body, like nature, is an alkaline earth metal. So, in its pure form, the element is silver-white, shiny and light. The hardness of alkaline earth metals is higher than that of alkaline.

Calcium index - about 3 points. The same hardness has a gypsum. The 20th element is cut by a knife, but it is much more difficult than any of just alkali metal.

What is the essence of the name "alkaline earth"? So calcium and other metals of his group dubbed alchemists. The oxides of the elements they called the lands. Oxides of substances calcium Groups Apply an alkaline environment.

However, radium, barium, as well as the 20th element, are found not only in combination with oxygen. In nature, many salts of calcium. The most famous of them is the calcite mineral. Carbon dioxide form of metal - not sensitive chalk, limestone and plaster. Each of them is calcium carbonate.

There are 20 elements and volatile connections. They paint the flame into orange-red, which becomes one of the markers to determine the substances.

All alkaline earth metals are burning easily. So that calcium entered into the reaction with oxygen, sufficiently conventional conditions. Only here in nature the element does not occur in its pure form, only in connections.

Oxy calcium- The film that is covered with metal, it is in air. Flip yellowish. It is hidden not only standard oxides, but also peroxide, nitrides. Out of calcium is not in air, but in water, he will outstand hydrogen from it.

At the same time, the precipitate falls calcium hydroxide. Pure metal residues float to the surface, pushed by hydrogen bubbles. The same scheme works with acids. With salt, for example, in the sediment falls calcium chlorideand hydrogen is distinguished.

For some reactions, high temperature is needed. If it comes to 842 degrees, calcium can bemelt. At 1,484-on-scale Celsius, the metal boils.

Calcium solution, like a clean element, is well carried out warm and electric current. But, if the substance is strongly heated, the metal properties are lost. That is, they do not have them in the molten, nor in gaseous calcium.

In the human body, the element is represented by solid and liquid aggregate states. Softened calcium waterwhich is present in, transfers easier. Outside the bones there is only 1% of the 20th substance.

However, its transportation on tissues plays an important role. Calcium blood adjusts the contraction of the muscles, including cardiac, it maintains blood pressure in normal.

Calcium use

In its pure form, the metal is used in. They go to battery lattices. The presence in calcium alloy is 10-13% reduces battery self-discharge. This is especially important for stationary models. From the mixture of lead and the 20th element are manufactured, also bearings. One of the alloys is called - bearing.

In the photo products containing calcium

The steel alkaline earth metal is added to clean the alloy from sulfur impurities. The reductional properties of calcium are also impressed in the production of uranium, chromium, cesium, rubidium ,.

What calciumapply in ferrous metallurgy? All the same clean. The difference in the assignment of the element. Now, he plays a role. This is an additive to alloys that reduces the temperature of their formation and facilitating the slag separation. Calcium granules fall asleep in electrovacuum instruments to remove tracks from them.

The 48th isotope calcium is in demand at atomic enterprises. There are superheavy elements. Raw materials are obtained at core accelerators. Accelerate them with the help of ions - peculiar shells. If CA48 acts in their role, the synthesis efficiency increases hundreds of times compared with the use of ions of other substances.

In optics, the 20th element is already valued as compounds. Calcium fluoride and tungsten become lenses, lenses and astronomical instrument prisms. Minerals and laser technology are found.

Calcium fluoride Geologies are referred to as a fluorite, and Wolframid - Scheelite. For the optical industry, their single crystals are selected, that is, individual, large units with a continuous grid and a clear form.

In medicine, the non-pure metal, but a substance based on it, is prescribed. They are easier to assimilate the organism. Calcium gluconate- The cheapest tool is used in osteoporosis. A drug " Calcium magnesium»We are prescribed to adolescents, pregnant women and older citizens.

It is necessary for them to provide an enhanced body need in the 20th element, avoid development pathologies. Calcium and phosphoric exchange adjusts "Calcium D3". "D3" in the title means speaks about the presence of vitamin D. It is rare, but needed for a full assimilation calcium.

Instructionto "Calcium Nomed3"indicates that the drug refers to the pharmaceutical compositions of the combined action. The same is said about calcium chloride. It not only fills the deficit of the 20th element, but also saves from intoxication, as well as, is able to replace the blood plasma. With some pathological states it is necessary.

In pharmacies, the drug is also exhibited Calcium - acidascorbic. " Such a duo is prescribed during pregnancy, during breastfeeding. We need additive and teenagers.

Calcium mining

Calcium in products, minerals, connections, known to humanity since sincere. In the purest form, the metal was allocated only in 1808th year. Good luck smiled Chemphri Davy. The English physicist produced calcium by electrolysis of molten salts of the element. This method is used now.

However, industrialists are more often resorted to the second method, open after Chemphrey. Calcium is restored from its oxide. The reaction is triggered by powder, sometimes ,. The interaction passes under vacuum conditions at elevated temperatures. For the first time, calcium was allocated in this way in the middle of the last century, in the United States.

Calcium price

Metal calcium manufacturers are a bit. So, in Russia, deliveries are engaged, mainly a chapets mechanical plant. He is in Udmurtia. The company trades with granules, chips and slicing metal. The price tag for a ton of raw materials is kept in the area of \u200b\u200b1,500 dollars.

The goods are also offered some chemical laboratories, for example, society "Russian Chemist". Last, offers 100 grams calcium. Reviewsindicate that this is powder under oil. The cost of one package is 320 rubles.

In addition to proposals to buy real calcium, on the Internet traded and business plans for its production. Approximately 7 pages of theoretical calculations are asked about 200 rubles. Most plans are drawn up in 2015, that is, not yet lost the relevance.

Home / Lectures 1 Course / General and Organic Chemistry / Question 23. Calcium / 2. Physical and Chemical Properties

Physical properties. Calcium is a silver-white forged metal, which melts at a temperature of 850 degrees. C and boils at 1482 degrees. C. It is significantly harder alkali metals.

Chemical properties. Calcium - active metal. So under normal conditions, it easily interacts with air oxygen and halogens:

2 sa + o2 \u003d 2 CAO (calcium oxide);

CA + BR2 \u003d Savr2 (calcium bromide).

With hydrogen, nitrogen, gray, phosphorus, carbon and other non-metals calcium reacts when heated:

Sa + H2 \u003d San2 (calcium hydride);

3 sa + n2 \u003d sa3n2 (calcium nitride);

Sa + s \u003d sas (calcium sulfide);

3 CA + 2 P \u003d CA3R2 (calcium phosphide);

CA + 2 C \u003d CAC2 (calcium carbide).

FROM cold water Calcium interacts slowly, and with hot - very vigorous:

Ca + 2 H2O \u003d sa (OH) 2 + H2.

Calcium can take oxygen or halogens from oxides and halides of less active metals, i.e. possesses reducing properties:

5 CA + NB2O5 \u003d SAO + 2 NB;

• 1. Finding in nature
• 3. Receipt
• 4. Application

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Calcium | Directory Pesticides.ru.

Many people have knowledge of calcium limited only by the fact that this element is necessary for the health of bones and teeth. Where else it is contained why it is needed and how much is needed, not everyone needs. However, calcium is in a variety of compounds familiar to us, both natural and human obtained. Chalk and lime, stalactites and stalagmites Caves, ancient fossils and cement, plaster and alabaster, dairy products and drugs against osteoporosis - all this and much more differs in high calcium content.

For the first time, this element was received by G. Davy in 1808, and at first he was used not particularly actively. Nevertheless, now this metal is the fifth in the world in the world, and the need for it increases the year from year. The main scope of use of calcium is to obtain building materials and mixtures. Nevertheless, it is necessary to build not only houses, but also of living cells. In the human body, calcium is part of the skeleton, makes muscle abbreviations possible, provides blood clotting, regulates the activity of a number of digestive enzymes and performs other, rather numerous functions. It is no less important for other living objects: animals, plants, mushrooms and even bacteria. At the same time, the need for calcium is high enough, which makes it possible to attribute it to the number of macroelements.

Calcium (Calcium), CA - the chemical element of the main subgroup II of the periodic Mendeleev periodic system. Atomic number - 20. Atomic mass - 40.08.

Calcium - alkaline earth metal. In the free state of dust, pretty solid, white. By density relates to light metals.

• Density - 1.54 g / cm3,
• Melting point - +842 ° C,
• Boiling point - +1495 ° C.

Calcium has pronounced metal properties. In all connections, the degree of oxidation is +2.

The air is covered with a layer of oxide, when heated, burns with a reddish, bright flame. With cold water, it reacts slowly, and hydrogen turns out of hot quickly and forms hydroxide. When interacting with hydrogen forming hydrides. At room temperature, it comes into interaction with nitrogen, forming nitrides. Also easily connects with halogens and sulfur, it restores the metal oxide when heated.

Calcium is among the most common elements in nature. In the earth's crust, its content is 3% of the mass. It is found in the form of deposits of chalk, limestone, marble (natural variety of calcium carbonate Caco3). In large quantities there are gypsum deposits (Caso4 x 2H3O), phosphorite (CA3 (PO4) 2 and various calcium-containing silicates.

Water

. Calcium salts are almost always present in natural water. Of these, only gypsum is slightly soluble in it. When the content of carbon dioxide in water, calcium carbonate passes into the solution in the form of CA hydrocarbonate (HCO3) 2.

Hard water

. Natural water with a large amount of calcium or magnesium salts is called tough.

Soft water

. With a small content of these salts or their absence, the water is called soft.

Soil

. As a rule, the soil is sufficiently secured by calcium. And, since calcium is contained in a larger mass in the vegetative part of the plants, its removal with harvest is insignificant.

Calcium loss from the soil occur as a result of washing into its precipitation. This process depends on the granulometric composition of the soil, the amount of precipitation, plants, forms and doses of lime and mineral fertilizers. Depending on the indicated factors, the loss of calcium from the arable layer ranges from several tens to 200 - 400 kg / ha or more.

Calcium content in various types of soil

Podzolic soils contain 0.73% (from dry matter soil) calcium.

Gray forest - 0.90% calcium.

Chernozem - 1.44% calcium.

Serozia - 6.04% calcium.

In the plant, calcium is in the form of phosphates, sulfates, carbonates, in the form of pectin salts and oxalic acids. Almost 65% of calcium in plants can be removed by water. The rest is the treatment of weak acetic and hydrochloric acids. Most calcium is contained in aging cells.

Symptoms of calcium lack according to:
Culture	Symptoms deficiency
General symptoms	The sponge of the top kidney; The whim of young leaves; The tips of the leaves bent down; The edges of the leaves are tightened up;
Potatoes	The top leaves are poorly bloom; Dextes the growth point of the stem; At the edges of the leaves - a light strip, subsequently she darkens; The edges of the leaves are spinled up;
Cabbage white and colored cabbage	On the leaves of young plants, chlorotic spotty (marble) or white stripes at the edges; In old plants, the leaves are twisted, and burns appear on them; Growth point is dying
	Demiste end lobes of leaves Flowers are falling; On the fruits in the vertex part there is a dark spot, which as the fetus increases increases (the vertex rotten of tomatoes)
	Top kidneys die; The edges of young leaves are wrapped up, the kind of ribbon, subsequently die; Dying the tops of the shoots; Damage to the tips of the roots; In the pulp of fruits - brown spots (bitter eggs); The taste of fruits deteriorates; The marketability of fruits is reduced

Calcium functions

The effect of this element on the plants is multilateral and, as a rule, positive. Calcium:

• Enhances metabolism;
• Plays an important role in the movement of carbohydrates;
• It affects the metamorphosis of nitrogenous substances;
• Accelerates the costs of seed proteins during germination;
• Plays a role in the process of photosynthesis;
• a strong antagonist of other cations, prevents their redundant entry into plant tissue;
• Affects the physicochemical properties of protoplasm (viscosity, permeability, etc.), and therefore, the normal flow of biochemical processes in the plant;
• Calcium compounds with pectin substances glue the walls of individual cells among themselves;
• Affects the activity of enzymes.

It should be noted that the influence of calcium compounds (lime) on the activity of enzymes is expressed not only in direct action, but also due to the improvement of the physicochemical properties of the soil and its nutritional mode. In addition, the limestation of the soil significantly affects the processes of biosynthesis of vitamins.

Disadvantage (deficiency) calcium in plants

The lack of calcium primarily affects the development of the root system. The root formation of root hairs is stopped. Outdoor root cells are destroyed.

This symptom is manifested both with a lack of calcium and in violation of the nutrient solution, that is, predominantly in it monovalent sodium, potassium and hydrogen cations.

In addition, the presence of a nitrate nitrogen in the soil solution enhances the flow of calcium in the tissue of plants, and the ammonia - reduces.

Signs of calcium starvation are expected when calciting containing less than 20% of the tank cationic capacity.

Symptoms. Visually, calcium deficiency is set to the following features:

• At the roots of plants there are damaged tips of the brown color;
• Growth point is deformed and dies;
• Flowers, wound up and buds fall;
• Fruits are damaged to necrosis;
• There is a chlorotic leaf;
• The top kidney dies, and the height of the stem ceases.

High sensitivity to the presence of calcium differ cabbage, alfalfa, clover. It has been established that these same plants are characterized by an increased sensitivity to soil acidity.

Calcium mineral poisoning leads to exclusive chlorosis with whiteish necrotic stains. They can be painted either to have concentric rings filled with water. Some plants respond to an excess of calcium with increasing leaf outlets, eliminating shoots and falling leaves. Symptoms are similar to the lack of iron and magnesium.

Calcium replenishment source in soil - lime fertilizers. They are divided into three groups:

• Solid lime breeds;
• Soft lime breeds;
• Waste industry with elevated lime content.

Solid lime breeds in the content of CAO and MGO are divided into:

• limestone (55-56% SAO and up to 0.9% MGO);
• limestones Dolomitized (42-55% SAO and up to 9% MGO);
• dolomites (32-30% SAO and 18-20% MGO).

Limestone

- Main lime fertilizers. Contain 75-100% SA and MG oxides in terms of Saso3.

Dolomitized limestone

. Contains 79-100% of the active ingredient (d.) In terms of Saso3. It is recommended in crop rotatures with potatoes, legumes, flax, root, and also on soils of strongly resolved types.

Marl

. Contains up to 25-15% Saso3 and impurities in the form of clay with sand up to 20-40%. Spent slowly. Recommended for use on light soils.

a piece of chalk

. Contains 90-100% SASO3. The action is faster than limestone. It is a valuable lime fertilizer in thinragus form.

Luggage lime

(SAO). Saso3 content is over 70%. It is characterized as a strong and high-speed lime material.

Slaked lime

(Sa (he) 2). Saso3 content - 35% or more. It is also a strong and high-speed lime fertilizer.

Dolomitic flour

. The content of SASO3 and MGCO3 is about 100%. In the action of slower than limestone tuffs. Usually used where magnesium is required.

Lime tuffs

. The content of SASO3 - 15-96%, impurities - up to 25% of clay and sand, 0.1% P2O5. The action is faster than limestone.

Defectation dirt (defect)

. It consists of SASO3 and CA (OH) 2. The content of lime at the SAO - up to 40%. Azot is also present - 0.5% and P2O5 - 1-2%. These are waste of beetroot plants. It is recommended for use not only to reduce soil acidity, but also in the areas of breeding on chernozem soils.

Shale ash cyclone

. Dry dusty material. The content of the active substance is 60-70%. Refers to industrial waste.

Dust stoves and cement plants

. The content of SASO3 should exceed 60%. In practice, applied in farms located in close proximity to cement plants.

Metallurgical slags

. Used in the regions of the Urals and Siberia. Ungigroscopic, easily sprayed. Must contain at least 80% SASO3, have no more than 2% humidity. Granulometric composition is important: 70% - less than 0.25 mm, 90% - less than 0.5 mm.

Organic fertilizers. The CA content in terms of Saso3 is 0.32-0.40%.

Phosphoritic flour. Calcium content - 22% on Saso3.

Lime fertilizers are applied not only to provide soil and plants with calcium. The main purpose of their use is the limestation of soils. This is a reception of chemical amelioration. It is aimed at neutralizing the excess acidity of soil, to improve its agricultural, agrochemical and biological properties, the supply of plants by magnesium and calcium, mobilization and immobilization of macroelements and trace elements, the creation of optimal water-physical, physical, air conditions of cultivated plants.

EFFICIENCY OF CALLING SOIL

Simultaneously with the satisfaction of the needs of plants in calcium as an element of mineral nutrition, lime leads to multiple positive changes in soils.

The effect of limeting on the properties of some soils

Calcium contributes to the coagulation of soil colloids and the prevention of their washing. This leads to facilitating the soil processing, improving its aeration.

As a result of lime:

• sand humus soils increase their water-absorbing ability;
• at heavy clay soils, soil aggregates and luggage, improving the water permeability, are formed.

In particular, organic acids are neutralized and n-ions are displaced from the absorption complex. This leads to the elimination of the exchange and reduced hydrolytic acidity of the soil. At the same time, an improvement in the cationic composition of the soil absorbing complex is observed, which is due to the change of hydrogen ions and aluminum on calcium and magnesium cations. This increases the degree of saturation of soil bases and increases the absorption capacity.

Effect of limeting on plant supply by nitrogen

After the limestration, the positive agrochemical properties of the soil and its structure are capable of persist for several years. This contributes to the creation of favorable conditions for strengthening useful microbiological processes on the mobilization of nutrients. Amplifies the activity of ammonifiers, nitrifers, nitrofact bacteria, freely living in the soil.

The lime promotes strengthening the reproduction of nodule bacteria and improving the supply of plant-owner nitrogen. It has been established that on acidic soils, bacterial fertilizers lose their effectiveness.

Effect of limeting on plant supply by ash elements

Removing promotes the supply of plant with ash elements, since the activity of bacteria decomposes of organic phosphoric compounds of the soil and contributing to the transition of phosphates of iron and aluminum into the phosphorunox acid calcium salts available to plants. Conducting acidic soil enhances microbiological and biochemical processes, which, in turn, increases the number of nitrates, as well as the forms of phosphorus and potassium.

Effect of lime on the shape and availability of macroelements and trace elements

Calmization increases the amount of calcium, and when using dolomite flour - magnesium. At the same time, the toxic forms of manganese and aluminum become insoluble and passed to the deposited form. The availability of such elements as iron, copper, zinc, manganese, decreases. Nitrogen, sulfur, potassium, calcium, magnesium, phosphorus and molybdenum become more affordable.

The effect of limeting on the action of physiologically acidic fertilizers

LIVE increases the efficiency of physiologically acidic mineral fertilizers, especially ammonia and potash.

The positive effect of physiologically acidic fertilizers without making lime fades, and over time it is capable of moving into a negative one. So, at fertilized areas, yields are even less than incremented. The combination of limeting with the use of fertilizers increases their effectiveness by 25-50%.

During lime, enzymatic processes in the soil are activated, according to which indirectly judges its fertility.

Compiler: Grigorovskaya P.I.

Page made: 05.12.13 00:40

Last updated: 05/22/14 16:25

Literary sources:

Glinka N.L. General chemistry. Textbook for universities. Ed: L: Chemistry, 1985, from 731

Mineev V.G. Agrochemistry: Tutorial. - 2 edition, recycled and supplemented. - M.: MSU Publishing House, Colossi Publishing House, 2004.- 720 p., L. Il.: Il. - (classic university tutorial).

Petrov B.A., Seliverstors N.F. Mineral nutrition plants. Reference manual for students and gardeners. Ekaterinburg, 1998. 79 p.

Encyclopedia for children. Volume 17. Chemistry. / Chapters ed. V.A. Volodin. - M.: Avanta +, 2000. - 640 p., Il.

Yagodin B.A., Zhukov Yu.P., Kobzarenko V.I. Agrochemistry / edited by B.A. Yagodina. - M.: Kolos, 2002.- 584 C.: IL (textbooks and tutorials For higher students educational institutions).

Images (recycled):

20 CA Calcium, licensed CC by

Calcium Deficiency in Wheat, by Cimmyt, under license CC BY-NC-SA

www.pesticidy.ru.

Calcium and its role for humanity - chemistry

Calcium and his role for humanity

Introduction

Finding in nature

Obtaining

Physical properties

Chemical properties

Use calcium compounds

Biological role

Conclusion

Bibliography

Introduction

Calcium - element of the main subgroup of the second group, the fourth period of the periodic system chemical elements D. I. Mendeleeva, with atomic number 20. It is indicated by the CA symbol (lat. Calcium). Simple calcium substance (CAS number: 7440-70-2) - soft, chemically active silver-white metal-white metal.

Despite the widespread prevalence of the element number 20, even chemists and then not everyone saw elementary calcium. But this metal and outwardly and on behavior is completely unlike alkali metalsCommunication with which is fraught with the danger of fires and burns. It can be calmly stored in the air, it does not ignite from the water. The mechanical properties of elementary calcium do not make it a "whiteframe" in the family of metals: the strength and hardness of calcium exceeds many of them; It can be swapped on the lathe, pull it into a wire, to join, press.

Nevertheless, elementary calcium is almost not used as a structural material. For this, it is too active. Calcium easily reacts with oxygen, gray, halogens. Even with nitrogen and hydrogen under certain conditions, it enters the reaction. Carbon oxide medium, inert for most metals, for calcium - aggressive. It burns in the atmosphere CO and CO2.

History and origin of the name

The name of the element comes from the lat. CALX (in the Parental Calcis Padder) - "Lime", "Soft Stone". It was proposed by the English chemist Humphrey Davy, in 1808 we allocated metal calcium with electrolytic method. Davy subjected the electrolysis mixture of a wet gasheny lime with HGO mercury oxide on a platinum plate, which was an anode. The cathode served as a platinum wire, immersed in liquid mercury. As a result of electrolysis, calcium amalgam was obtained. Heat from her mercury, Davy got a metal called Calcium.

Calcium compounds - limestone, marble, plaster (as well as lime - limestone firing product) were used in the construction case for several thousand years ago. Until the end of the XVIII century, chemists considered lime with a simple body. In 1789, A. Lavauzier suggested that lime, magnesia, barite, alumina and silica - compound substances.

Finding in nature

Due to the high chemical activity of calcium in free form in nature, it is not found.

Calcium accounts for 3.38% of the mass of the earth's crust (5th place in prevalence after oxygen, silicon, aluminum and iron).

Isotopes. Calcium is found in nature in the form of a mixture of six isotopes: 40CA, 42CA, 43CA, 44CA, 46CA and 48CA, among which the most common - 40CA is 96.97%.

Of the six natural isotopes of calcium, five are stable. The sixth isotope 48ca, the hardest of six and very rare (its isotopic prevalence is only 0.187%), as was recently discovered, is the double beta decay with a half-life of 5.3? 1019 years.

In rocks and minerals. Most of the calcium is contained as part of silicates and aluminosilicates of various rocks (granites, gneisses, etc.), especially in the field Plug - Animal CA.

In the form of sedimentary solids, calcium is represented by chalk and limestones consisting mainly of calcite mineral (Caco3). Crystalline form of calcite - marble - occurs in nature much less often.

Calcite CaCO3, Anhydrite Caso4, Caso4 Alabaster · 0.5H3o and Caso4 Gypsum · 2H3O, CAF2 Fluorite, CAF2 Fluorite, Apatite CA5 (PO4) 3 (F, CL, OH), Dolomite MgCO3 · CaCO3, Dolomite MGCO3 · CaCO3 is quite widespread. The presence of calcium and magnesium salts in natural water is determined by its rigidity.

Calcium, energetically migrating in the earth's crust and accumulating in various geochemical systems, forms 385 minerals (fourth place in terms of minerals).

Migration in the earth's crust. In the natural migration of calcium, the "carbonate equilibrium" plays a significant role associated with reversible reaction Calcium carbonate interactions with water and carbon dioxide with the formation of soluble hydrocarbonate:

Saso3 + H3O + CO2 - CA (NSO3) 2 - CA2 + + 2HCO3-

(Equilibrium is shifted to the left or right depending on the concentration of carbon dioxide).

Biogenic migration. In the calcium compound biosphere, there are practically in all animals and vegetable tissues (see. Below). A significant amount of calcium is included in living organisms. Thus, hydroxyapatite CA5 (PO4) 3OH, or, in another record, 3CA3 (PO4) 2 · CA (OH) 2 - the base of the bone vertebral bone tissue, including a person; Caco3 calcium carbonate consists of sinks and polyziri of many invertebrates, egg shell, etc. in the living tissues of man and animals 1.4-2% Ca (by mass fraction); In the human body weighing 70 kg calcium content - about 1.7 kg (mainly in the composition of the intercellular substance of bone tissue).

Obtaining

Free metal calcium is obtained by the electrolysis of the melt consisting of CaCl2 (75-80%) and KCl or from CaCl2 and CaF2, as well as aluminothermic recovery of Cao at 1170--1200 ° C:

4CAO + 2AL \u003d Caal2O4 + 3CA.

Physical properties

Calcium metal exists in two allotropic modifications. Up to 443 ° C is stable? -CA with a cubic grazenarized grid (parameter A \u003d 0.558 nm), above stable? -CA with a cubic volume-centered type? -Fe grid (parameter a \u003d 0.448 nm). Standard enthalpy? H0 transition? \u003e? This is 0.93 kJ / mol.

Chemical properties

Calcium - typical alkaline earth metal. The chemical activity of calcium is high, but lower than all other alkaline earth metals. It easily interacts with oxygen, carbon dioxide and air moisture, due to which the surface of the metal calcium is usually dimly grazing, therefore, in the calcium laboratory, it is usually stored, like other alkaline earth metals, in a tightly closed can under a layer of kerosene or liquid paraffin.

In the number of standard calcium potentials is located to the left of hydrogen. Standard electrode potential CA2 + / CA0 pair? 2.84 V, so calcium actively reacts with water, but without ignition:

Ca + 2N2O \u003d Ca (OH) 2 + H2 ^ + Q.

With active non-metals (oxygen, chlorine, bromine), calcium reacts under normal conditions:

2S + O2 \u003d 2SAO, CA + BR2 \u003d CABR2.

When heated in air or in calcium oxygen is flammable. With less active non-metals (hydrogen, boron, carbon, silicon, nitrogen, phosphorus, and other), calcium enters into interaction when heated, for example:

Sa + H2 \u003d San2, CA + 6B \u003d CAB6,

3CA + N2 \u003d CA3N2, CA + 2C \u003d CAC2,

3s + 2p \u003d sa3r2 (

calcium phosphide), also known phosphides calcium compositions of SAR and SAR5;

2CA + Si \u003d CA2SI

(calcium silicide), also known calcium silicides CASI, CA3SI4 and CASI2 compositions.

The flow of the above reactions is usually accompanied by the release of a large amount of heat (that is, these reactions are exothermic). In all connections with non-metals, the degree of calcium oxidation is +2. Most of the calcium compounds with non-metals are easily decomposed with water, for example:

San2 + 2N2O \u003d sa (it) 2 + 2N2 ^,

CA3N2 + 3N2O \u003d 3A (OH) 2 + 2NH4 ^.

Ion Ca2 + Besmevetn. When in the flame of soluble calcium salts, the flame is painted in brick-red.

Calcium salts such as CaCl2 chloride, CABR2 bromide, CAI2 iodide and Ca nitrate (NO3) 2 are well soluble in water. Insoluble in water Fluoride CAF2, Caco3 carbonate, Caso4 sulfate, orthophosphate CA3 (PO4) 2, SAS2O4 oxalate and some others.

The factory is important that, in contrast to calcium carbonate CASSO3, acid calcium carbonate (hydrocarbonate) Ca (NSO3) 2 in water is soluble. In nature, this leads to the following processes. When cool rain or river water, saturated with carbon dioxide, penetrates under the ground and falls on limestone, then their dissolution is observed:

Saso3 + CO2 + H2O \u003d CA (NSO3) 2.

In the same places where the water saturated with calcium bicarbonate goes to the surface of the Earth and heated by the solar rays, the reverse reaction flows:

Ca (NSO3) 2 \u003d Saso3 + CO2 ^ + H2O.

So in nature the transfer of large masses. As a result, huge failures may form underground, and beautiful stone "icicles" - stalactites and stalagmites are formed in the caves.

The presence of a dissolved calcium bicarbonate in water largely determines the time rigidity of water. It is called temporary because, when boiling water, the bicarbonate is decomposed, and Saso3 falls into the precipitate. This phenomenon leads, for example, to the fact that in the teapot, scale is formed.

Application of metallic calcium

The main use of metal calcium is the use of it as a reducing agent when producing metals, especially nickel, copper and stainless steel. Calcium and its hydride are also used to obtain hard-established metals, such as chrome, thorium and uranium. Calcium alloys with lead are used in batteries and bearing alloys. Calcium granules are also used to remove traces of air from electrovacuum instruments.

Metalothermia

Pure metallic calcium is widely used in metalothermia when obtaining rare metals.

Alloy doping

Pure calcium is used to doping lead, which is on the manufacture of battery plates, maintainable starter lead-acid batteries with a small self-discharge. Also, the metal calcium is on the production of high-quality calcium babbits of the BKA.

Nuclear fusion

Isotope 48CA is the most efficient and consumer material for the production of super-temperature elements and the discovery of new elements of the Mendeleev table. For example, in the case of using 48CA ions to obtain superheuma elements on the core accelerators of these elements, hundreds and thousands of times more efficiently than when using other shells (ions).

Use calcium compounds

Hydride calcium. Calcium heating in the hydrogen atmosphere is obtained by CAH3 (calcium hydride) used in metallurgy (metal) and when producing hydrogen in field conditions.

Optical and laser materials. Calcium fluoride (fluorite) is used in the form of single crystals in optics (astronomical lenses, lenses, prisms) and how laser material. Calcium Tungsten (Sheelit) in the form of single crystals is used in laser technology, as well as as a scintillator.

Calcium carbide. Calcium carbide CAC2 is widely used to obtain acetylene and for the restoration of metals, as well as upon receipt of calcium cyanamide (heating calcium carbide in nitro at 1200 ° C, the reaction is Exothermally, carried out in cyanomic furnaces).

Chemical current sources. Calcium, as well as its alloys with aluminum and magnesium, are used in the backup thermal electrical batteries as an anode (for example, calcium-chromium element). Calcium chromate is used in such batteries as a cathode. The peculiarity of such batteries is an extremely long period of storage (decade) at suitable condition, the possibility of operation in any conditions (space, high pressure), large specific energy in weight and volume. Disadvantage in short time. Such batteries are used where necessary on short term Create a colossal electrical power (ballistic missiles, some spacecraft and etc.).

Refractory materials. Calcium oxide, both in free form and in the composition of ceramic mixtures, is used in the production of refractory materials.

Medicines. Calcium compounds are widely used as an antihistamine.

Calcium chloride

Calcium gluconate

Calcium glycera phosphate

In addition, calcium compounds are introduced into preparations for the prevention of osteoporosis, in vitamin complexes for pregnant and elderly.

Biological role

Calcium is a common macro-element in the body of plants, animals and humans. In the human body and other vertebrates most of its part are contained in the skeleton and teeth in the form of phosphates. Of various shapes Calcium carbonate (lime) consist of skeletons of most groups of invertebrates (sponges, coral polyps, mollusks, etc.). Calcium ions are involved in blood coagulation processes, as well as in ensuring constant osmotic blood pressure. Calcium ions also serve as one of the universal secondary intermediaries and regulate a variety of intracellular processes - muscle contraction, exocytosis, including the secretion of hormones and neurotransmitters and others. Calcium concentration in the cytoplasm of human cells is about 10? 7 mol, in intercellular fluids about 10 ? 3 mole.

The need for calcium depends on age. For adults, the necessary daily rate ranges from 800 to 1000 milligrams (mg), and for children from 600 to 900 mg, which is very important for children due to the intensive growth of the skeleton. Most of the calcium entering the human body with food is found in dairy products, the remaining calcium comes from meat, fish, and some vegetable products (especially much contain bean). Suction occurs both in a thick and small intestine and is facilitated by an acidic medium, vitamin D and vitamin C, lactose, unsaturated fatty acids. It is important for the role of magnesium in calcium exchange, with its lack of calcium "washed out" from the bones and deposits in the kidneys (kidney stones) and muscles.

Calcium absorption is hampered aspirin, oxalic acid, derivatives of estrogen. Connecting with oxalic acid, calcium gives insoluble connections in water, which are components of stones in the kidneys.

Calcium content in the blood due to the large number of processes related to it is precisely adjustable, and with proper nutrition, the deficit does not occur. A long absence in the diet may cause cramps, pain in the joints, drowsiness, growth defects, as well as constipation. A deeper deficit leads to constant muscle cramps and osteoporosis. Abuse of coffee and alcohol may be causes of calcium deficiency, as part of it is removed with the urine.

Excessive doses of calcium and vitamin D can cause hypercalcemia, after which intensive calcification of bones and tissues follows (mainly affects the urinary system). Long extension disrupts the functioning of muscle and nerve tissues, increases blood coagulation and reduces the digestibility of zinc cells of bone tissue. The maximum daily safe dose is an adult from 1500 to 1800 milligrams.

Calcium products, mg / 100 g

Schorts 783.

Nettle 713.

Lesnik Forest 505

Plantain big 412.

GalinSog 372.

Sardines in oil 330

Wrushoid butders 289.

Rosehip dog 257.

Almond 252.

Plantain Lancetolist. 248.

Forest nut 226.

Amaranth Seed 214.

Cress Salad 214

Soybean Beans Dry 201

Children up to 3 years old - 600 mg.

Children from 4 to 10 years old - 800 mg.

Children from 10 to 13 years old - 1000 mg.

Teens from 13 to 16 years old - 1200 mg.

Youth from 16 and older - 1000 mg.

Adults from 25 to 50 years - from 800 to 1200 mg.

Pregnant and breastfeeding women - from 1500 to 2000 mg.

Conclusion

Calcium is one of the most common elements on Earth. In nature, it is a lot of: from calcium salts, mountain ranges and clay rocks are formed, it is in sea and river water, it is included in the composition of plant and animal organisms.

Calcium is constantly surrounding citizens: almost all major building materials - concrete, glass, brick, cement, lime - contain this element in significant quantities.

Naturally, possessing such chemical propertiesCalcium can not be in nature in a free state. But calcium compounds - and natural and artificial - gained paramount importance.

Bibliography

1. Rartic.: Knunyantz I. L. (Ch. Ed.) Chemical Encyclopedia: In 5 tons - Moscow: Soviet Encyclopedia, 1990. - T. 2. - P. 293. - 671 with

2. Doronin. N. A. Calcium, Goshimzdat, 1962. 191 p. With ill.

3. Dotsenko VA. - Therapeutic and preventive nutrition. - Vopr. Power, 2001 - N1-C.21-25

4. Bilezikian J. P. Calcium and Bone Metabolism // In: K. L. Becker, ED.

www.e-ng.ru.

World of Science

Calcium - metal element of the main subgroup II of group 4 of the periodic system of chemical elements. It refers to the alkaline earth metals family. At the external energy level, the calcium atom contains 2 paired S electrons

Which it is able to vigorously give in chemical interactions. Thus, calcium is a reducing agent and in its compounds has a degree of oxidation + 2. With the nature of calcium occurs only in the form of salts. The mass fraction of calcium in the earth's crust is 3.6%. The main natural mineral calcium is Caco3 calcite and its varieties - limestone, chalk, marble. There are also living organisms (for example, corals), the backbone of which consists mainly of calcium carbonate. Also important calcium minerals is the dolomite CACO3 MGCO3, Fluorite CAF2, Caso4 2H3O gypsum, apatite, field spat, etc., plays an important role in the vital activity of living organisms. The mass fraction of calcium in the human body is 1.4-2%. It is part of the teeth, bones, other tissues and organs, participates in the process of blood coagulation, excites cardiac activity. To provide the body with a sufficient amount of calcium, it is necessary to consume milk and dairy products, green vegetables, fish. Surface substance of calcium is a typical silver-white metal. It is pretty solid, plastic, has a density of 1.54 g / cm3 and melting point 842? Smmically calcium is very active. Under normal conditions, it easily interacts with oxygen and air moisture, so it is stored in hermetically closed vessels. When heated in air, calcium flames and forms oxide: 2CA + O2 \u003d 2CAO.ca chlorine and the calcium bromine is reacting when heated, and with fluorine - even in the cold. The products of these reactions are appropriate halides, for example: CA + CL2 \u003d CASL2. In the heating of calcium with sulfur, calcium sulphide is formed: Ca + S \u003d Cas. Calcia can react with other non-metals. The weight of water leads to the formation of a low-soluble calcium hydroxide and the release of gaseous hydrogen : Ca + 2H3O \u003d Ca (OH) 2 + H3.Metallic calcium is widely used. It is used as a pattern in the manufacture of steels and alloys, as a reducing agent for obtaining some refractory metals.

Calcium is obtained by electrolysis of calcium chloride melt. Thus, calcium was first obtained in 1808 Hamphrey Davy.

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