Arsenic element description. Poisoning with arsenic and its salts - a lethal dose for humans, symptoms, treatment

The majority of the population of the newly formed USSR was represented primarily by peasants. The main task for the Bolsheviks was to prevent independent agricultural activity of the peasantry, since it excluded the principles on which the economic reforms of that time were based: collective responsibility and strict centralization.

Prerequisites for collectivization

The collectivization of agriculture at its initial stage was very sluggish and consisted of a few communes. The Bolshevik government supported and encouraged such initiatives, but was in no hurry to force peasants to unite farms.

The main deterrent for the Bolsheviks was that the main driving force of the revolution was precisely the peasants seeking the right to private land ownership. However, the authorities abandoned their liberal policies after rural residents began to massively organize cooperatives - private associations not controlled by the state.

Cooperation not only hampered centralization, but also the entire policy of the NEP. The Bolsheviks were forced to take radical measures, which consisted of virtually forced collectivization of agriculture.

Course towards collectivization

In 1927, the failure of the NEP became obvious even to the ruling elite of the CPSU (b). In December of this year at the 15th Party Congress I.V. Stalin announced a course towards complete collectivization of agriculture. At that time, this was the only way to replenish the empty state treasury.

Collective farms were supposed to become a reliable stronghold for the totalitarian communist regime. This policy did not find the support of some fairly influential party members who were aware of the consequences that forced collectivization would entail.

To eliminate such “undesirable elements,” Stalin personally carried out a purge of the party ranks - 15% of the Communists - Bolsheviks lost their party cards and were sent to Siberia.

The essence of collectivization in the USSR

Collectivization was the reform of agricultural production. Farmers and private farmers were forced to unite their farms into a collective organization controlled by the state. More than half of the manufactured products became state property.

Wealthy peasants who refused to run collective farms were deprived of all political and civil rights, sent into exile, and their property was confiscated and distributed equally between the state and the informer.

The main indicator of the efficiency of collective farms was the level of grain that peasants annually handed over to the state. In order to show their collective farm from the best side, local authorities began to forcibly take away grain from the peasants. Along with grain, other products were also selected: vegetables, fruits, and cereals.

The supreme power, led by Stalin, understood perfectly well how local officials acted, but did not interfere with this in any way - the country needed money for the upcoming industrialization.

The result of the predatory policy of the Bolsheviks was a large-scale famine and millions of repressed, innocent “enemies of the state.” The official completion of the collectivization process is considered to be 1937; at that time, more than 21 million peasant farms were collectivized, which was more than 95% of their total number.

During the period of formation and development of the Soviet state, the history of which began with the victory of the Bolsheviks during the October Revolution, there were many large-scale economic projects, the implementation of which was carried out by harsh coercive measures. One of them is the complete collectivization of agriculture, the goals, essence, results and methods of which became the topic of this article.

What is collectivization and what is its purpose?

Complete collectivization of agriculture can be briefly defined as the widespread process of merging small individual agricultural holdings into large collective associations, abbreviated as collective farms. In 1927, the next one took place, at which the course was set for the implementation of this program, which was then carried out in the main part of the country by

Complete collectivization, in the opinion of the party leadership, should have allowed the country to solve the then acute food problem by reorganizing small farms belonging to middle and poor peasants into large collective agricultural complexes. At the same time, the total liquidation of the rural kulaks, declared the enemy of socialist reforms, was envisaged.

Reasons for collectivization

The initiators of collectivization saw the main problem of agriculture in its fragmentation. Numerous small producers, deprived of the opportunity to purchase modern equipment, mostly used ineffective and low-productivity manual labor in the fields, which did not allow them to obtain high yields. The consequence of this was an ever-increasing shortage of food and industrial raw materials.

To solve this vital problem, complete collectivization of agriculture was launched. The start date of its implementation, which is generally considered to be December 19, 1927 - the day of completion of the XV Congress of the CPSU (b), became a turning point in the life of the village. A violent breakdown of the old, centuries-old way of life began.

Do this - I don’t know what

Unlike previously carried out agrarian reforms in Russia, such as those carried out in 1861 by Alexander II and in 1906 by Stolypin, collectivization carried out by the communists had neither a clearly developed program nor specifically designated ways of its implementation.

The party congress gave instructions for a radical change in policy regarding agriculture, and then local leaders were obliged to implement it themselves, at their own peril and risk. Even their attempts to contact the central authorities for clarification were suppressed.

The process has begun

Nevertheless, the process, which began with the party congress, began and already the next year covered a significant part of the country. Despite the fact that officially joining collective farms was declared voluntary, in most cases their creation was carried out through administrative and coercive measures.

Already in the spring of 1929, agricultural commissioners appeared in the USSR - officials who traveled to the field and, as representatives of the highest state power, monitored the progress of collectivization. They were given assistance from numerous Komsomol detachments, also mobilized to reorganize the life of the village.

Stalin about the “great turning point” in the life of peasants

On the day of the next 12th anniversary of the revolution - November 7, 1928, the Pravda newspaper published an article by Stalin, in which he stated that a “great turning point” had come in the life of the village. According to him, the country has managed to make a historic transition from small-scale agricultural production to advanced farming on a collective basis.

It also cited many specific indicators (mostly exaggerated), indicating that complete collectivization brought a tangible economic effect everywhere. From that day on, the editorials of most Soviet newspapers were filled with praise for the “victorious march of collectivization.”

Peasants' reaction to forced collectivization

The real picture was radically different from the one that the propaganda organs were trying to present. The forced confiscation of grain from peasants, accompanied by widespread arrests and destruction of farms, essentially plunged the country into a state of new civil war. At the time when Stalin spoke about the victory of the socialist reorganization of the countryside, peasant uprisings were raging in many parts of the country, numbering in the hundreds by the end of 1929.

At the same time, real agricultural production, contrary to statements by the party leadership, did not increase, but fell catastrophically. This was due to the fact that many peasants, fearing to be classified as kulaks, and not wanting to give their property to the collective farm, deliberately reduced crops and slaughtered livestock. Thus, complete collectivization is, first of all, a painful process, rejected by the majority of rural residents, but carried out using methods of administrative coercion.

Attempts to speed up the process

At the same time, in November 1929, a decision was made to intensify the ongoing process of restructuring agriculture to send 25 thousand of the most conscious and active workers to the villages to manage the collective farms created there. This episode went down in the history of the country as the “twenty-five thousanders” movement. Subsequently, when collectivization took on an even greater scale, the number of city envoys almost tripled.

An additional impetus to the process of socialization of peasant farms was given by the resolution of the Central Committee of the All-Union Communist Party of Bolsheviks of January 5, 1930. It indicated specific deadlines within which complete collectivization was to be completed in the main arable areas of the country. The directive prescribed their final transfer to a collective form of management by the fall of 1932.

Despite the categorical nature of the resolution, it, as before, did not give any specific explanations regarding the methods of involving the peasant masses in collective farms and did not even give a precise definition of what the collective farm was ultimately supposed to be. As a result, each local boss was guided by his own idea of ​​this, unprecedented form of organization of work and life.

Arbitrariness of local authorities

This state of affairs became the reason for numerous cases of local self-government. One such example is Siberia, where local officials, instead of collective farms, began to create certain communes with the socialization of not only livestock, equipment and arable land, but also all property in general, including personal belongings.

At the same time, local leaders, competing with each other to achieve the highest percentages of collectivization, did not hesitate to use brutal repressive measures against those who tried to evade participation in the ongoing process. This caused a new explosion of discontent, which in many areas took the form of open rebellion.

Famine resulting from the new agricultural policy

Nevertheless, each individual district received a specific plan for the collection of agricultural products intended both for the domestic market and for export, for the implementation of which the local leadership was personally responsible. Each short delivery was considered a sign of sabotage and could have tragic consequences.

For this reason, a situation arose in which the heads of districts, fearing liability, forced collective farmers to hand over to the state all available grain, including the seed fund. The same picture was observed in livestock farming, where all breeding cattle were sent to slaughter for reporting purposes. The difficulties were also aggravated by the extreme incompetence of collective farm leaders, most of whom came to the village at the party call and had no idea about agriculture.

As a result, the complete collectivization of agriculture carried out in this way led to interruptions in the food supply of cities, and in villages - to widespread hunger. It was especially destructive in the winter of 1932 and spring of 1933. At the same time, despite the obvious miscalculations of the leadership, the official bodies blamed what was happening on certain enemies trying to hinder the development of the national economy.

Elimination of the best part of the peasantry

A significant role in the actual failure of the policy was played by the elimination of the so-called class of kulaks - wealthy peasants who managed to create strong farms during the NEP period and produced a significant part of all agricultural products. Naturally, it did not make sense for them to join collective farms and voluntarily lose the property acquired by their labor.

Since such an example did not fit into the general concept of arranging village life, and they themselves, in the opinion of the party leadership of the country, prevented the involvement of the poor and middle peasants in collective farms, a course was taken to eliminate them.

A corresponding directive was immediately issued, on the basis of which kulak farms were liquidated, all property was transferred to the ownership of collective farms, and they themselves were forcibly evicted to the regions of the Far North and Far East. Thus, complete collectivization in the grain-growing regions of the USSR took place in an atmosphere of total terror against the most successful representatives of the peasantry, who constituted the main labor potential of the country.

Subsequently, a number of measures taken to overcome this situation made it possible to partially normalize the situation in the villages and significantly increase the production of agricultural products. This allowed Stalin, at the party plenum held in January 1933, to declare the complete victory of socialist relations in the collective farm sector. It is generally accepted that this was the end of the complete collectivization of agriculture.

How did collectivization end up?

The most eloquent evidence of this is the statistical data released during the years of perestroika. They are amazing even though they are apparently incomplete. It is clear from them that the complete collectivization of agriculture ended with the following results: during its period, over 2 million peasants were deported, with the peak of this process occurring in 1930-1931. when about 1 million 800 thousand rural residents were subjected to forced relocation. They were not kulaks, but for one reason or another they found themselves unpopular in their native land. In addition, 6 million people became victims of famine in villages.

As mentioned above, the policy of forced socialization of farms led to mass protests among rural residents. According to data preserved in the archives of the OGPU, in March 1930 alone there were about 6,500 uprisings, and the authorities used weapons to suppress 800 of them.

In general, it is known that that year over 14 thousand popular uprisings were recorded in the country, in which about 2 million peasants took part. In this regard, one often hears the opinion that complete collectivization carried out in this way can be equated to the genocide of one’s own people.

Arsenic is a non-metal and forms compounds similar in its chemical properties. However, along with non-metallic properties, arsenic also exhibits metallic ones. In air under normal conditions, arsenic is slightly oxidized from the surface. Arsenic and its analogues are insoluble neither in water nor in organic solvents.

Arsenic is chemically active. In air at normal temperatures, even compact (fused) metallic arsenic is easily oxidized; when heated, powdered arsenic ignites and burns with a blue flame to form As 2 O 3 oxide. Thermally less stable non-volatile oxide As 2 O 5 is also known.

When heated (in the absence of air), As sublimes (sublimation temperature 615 o C). The steam consists of As 4 molecules with an insignificant (about 0.03%) admixture of As 2 molecules.

Arsenic belongs to the group of oxidizing-reducing elements. When exposed to strong reducing agents, it exhibits oxidizing properties. Thus, under the action of metals and hydrogen at the moment of release, it is capable of producing the corresponding metal and hydrogen compounds:

6Ca +As 4 = 2Ca 3 As 2

Under the influence of strong oxidizing agents, arsenic transforms into a tri- or pentavalent state. For example, when heated in air, arsenic, oxidized by oxygen, burns and forms white smoke - arsenic (III) oxide As 2 O 3:

As 4 + 3O 2 =2As 2 O 3

Stable forms of arsenic oxide in the gas phase are sesquioxide (arsenic anhydride) As 2 O 3 and its dimer As 4 O 6. Up to 300 o C, the main form in the gas phase is a dimer; above this temperature it is noticeably dissociated, and at temperatures above 1800 o C the gaseous oxide consists practically of monomeric As 2 O 3 molecules.

A gaseous mixture of As 4 O 6 and As 2 O 3 is formed during the combustion of As in oxygen, during the oxidative roasting of As sulfide minerals, such as arsenopyrite, non-ferrous metal ores and polymer ores.

When As 2 O 3 (As 4 O 6) vapor condenses above 310 o C, the glassy form of As 2 O 3 is formed. When steam condenses below 310 o C, a colorless polycrystalline cubic modification of arsenolite is formed. All forms of As 2 O 3 are highly soluble in acids and alkalis.

As(V) oxide (arsenic anhydride) As 2 O 5 – colorless crystals of the orthorhombic system. When heated, As 2 O 5 dissociates into As 4 O 6 (gas) and O 2 . As 2 O 5 is obtained by dehydrating concentrated solutions of H 3 AsO 4 followed by calcination of the resulting hydrates.

The oxide As 2 O 4 is known, obtained by sintering As 2 O 3 and As 2 O 5 at 280 o C in the presence of water vapor. Gaseous AsO monoxide is also known, which is formed during an electrical discharge in As trioxide vapor at reduced pressure.

When dissolved in water, As 2 O 5 forms orthoarsenic H 3 AsO 3 , or As(OH) 3 , and metaarsenic HAsO 2 , or AsO(OH), which exist only in solution and have amphoteric, predominantly acidic, properties.

In relation to acids, arsenic behaves as follows:

— arsenic does not react with hydrochloric acid, but in the presence of oxygen arsenic trichloride AsCl 3 is formed:

4As +3O 2 +12HCl = 4AsCl 3 +6H 2 O

- dilute nitric acid, when heated, oxidizes arsenic to orthoarsenic acid H 3 AsO 3 , and concentrated nitric acid – to orthoarsenic acid H 3 AsO 4:

3As + 5HNO 3 + 2H 2 O = 3H 2 AsO 4 +5NO

Orthoarsenic acid(arsenic acid) H 3 AsO 4 *0.5H 2 O – colorless crystals; melting point – 36 o C (with decomposition); soluble in water (88% by weight at 20 o C); hygroscopic; in aqueous solutions – tribasic acid; when heated to about 100 o C, it loses water, turning into pyroarsenic acid H 4 As 5 O 7, at higher temperatures it turns into metaarsenic acid HAsO 3. Obtained by oxidation of As or As 2 O 3 with concentrated HNO 3 . It is easily soluble in water and is approximately equal in strength to phosphorus.

The oxidizing properties of arsenic acid are noticeable only in an acidic environment. Arsenic acid is capable of oxidizing HI to I 2 by reversible reactions:

H 3 AsO 4 + 2HI = H 3 AsO 3 + I 2 + H 2 O

Orthoarsenic acid (arsenous acid) H 3 AsO 3 exists only in aqueous solution; weak acid; obtained by dissolving As 2 O 3 in water; intermediate product in the preparation of arsenites (III) and other compounds.

- concentrated sulfuric acid reacts with arsenic according to the following equation to form orthoarsenic acids:

2As + 3H 2 SO 4 = 2H 3 AsO 3 +3SO 2

- alkali solutions do not react with arsenic in the absence of oxygen. When arsenic is boiled with alkalis, it is oxidized into the arsenic acid salt H 3 AsO 3 . When fused with alkalis, arsine (arsenous hydrogen) AsH 3 and arsenates (III) are formed. Apply AsH 3

for doping semiconductor materials with arsenic to obtain high purity As.

Unstable higher arsines are known: diarsine As 2 H 4, decomposes already at -100 o C; triarsine As 3 H 5 .

Metallic arsenic easily reacts with halogens, giving volatile halides AsHal 3:

As +3Cl 2 = 2AsCl 3

AsCl 3 is a colorless oily liquid that fumes in air and, when solidified, forms crystals with a pearlescent sheen.

C F 2 also forms AsF 5 - pentafluoride - a colorless gas, soluble in water and alkali solutions (with a small amount of heat), in diethyl ether, ethanol and benzene.

Powdered arsenic spontaneously ignites in an environment of F 2 and Cl 2 .

With S, Se and Te, arsenic forms the corresponding chalcogenides:

sulfides - As 2 S 5, As 2 S 3 (orpiment mineral in nature), As 4 S 4 (realgar mineral) and As 4 S 3 (dimorphite mineral); selenides – As 2 Se 3 and As 4 Se 4; telluride – As 2 Te 3 . Arsenic chalcogenides are stable in air, insoluble in water, highly soluble in alkali solutions, and when heated - in HNO 3. They have semiconductor properties and are transparent in the IR region of the spectrum.

With most metals it gives metallic compounds - arsenides. Gallium arsenide and indium arsenide– important semiconductor compounds.

There are numerous known arsenicorganic connections. Organoarsenic compounds contain an As-C bond. Sometimes organoarsenic compounds include all organic compounds containing As, for example, esters of arsenic acid (RO) 3 As and arsenic acid (RO) 3 AsO. The most numerous group of organoarsenic compounds are As derivatives with a coordination number of 3. This includes organoarsines R n AsH 3-n, tetraorganodiarsines R 2 As-AsR 2, cyclic and linear polyarganoarsines (RAs) n, as well as organoarsonic and diarganoarsinous acids and their derivatives R n AsX 3-n (X= OH, SH, Hal, OR', NR 2', etc.). Most organoarsenic compounds are liquids, polyorganoarsines and organic acids As are solids, CH 3 AsH 2 and CF 3 AsH 2 are gases. These compounds, as a rule, are soluble in organic solvents, limitedly soluble in water, and relatively stable in the absence of oxygen and moisture. Some tetraorganodiarsines are flammable in air.

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General information

Uniqueness arsenic is that it can be found everywhere - in rocks, minerals, water, soil, animals and plants. It is even called the omnipresent element. Arsenic is distributed over different geographic regions of the Earth due to the volatility of its compounds and their high solubility in water. If the region's climate is humid, the element is washed out of the ground and then carried away by groundwater. Surface waters and the depths of rivers contain from 3 µg/l to 10 µg/l of the substance, and sea and ocean water contain much less, about 1 µg/l.

Arsenic occurs in the adult human body in amounts of approximately 15 mg. Most of it is found in the liver, lungs, small intestine and epithelium. Absorption of the substance occurs in the stomach and intestines.
The antagonists of the substance are phosphorus, sulfur, selenium, vitamins E, C, as well as some amino acids. In turn, the substance impairs the body’s absorption of selenium, zinc, vitamins A, E, C, and folic acid.
The secret of its benefits is in its quantity: in a small dose it performs a number of useful functions; and in large ones it is a powerful poison.

Functions:

• Improving the absorption of phosphorus and nitrogen.
• Stimulation of hematopoiesis.
• Weakening of oxidative processes.
• Interaction with proteins, lipoic acid, cysteine.

The daily need for this substance is small - from 30 to 100 mcg.

Arsenic as a chemical element

Arsenic is classified as a chemical element of group V of the periodic table and belongs to the nitrogen family. Under natural conditions, this substance is represented by the only stable nuclide. More than a dozen radioactive isotopes of arsenic have been artificially obtained, with a wide range of half-life values ​​- from a couple of minutes to a couple of months. The formation of the term is associated with its use for the extermination of rodents - mice and rats. Latin name Arsenicum (As) derived from the Greek word " arsen", What means: powerful, strong.

Historical information

Arsenic in its pure form was discovered during alchemical experiments in the Middle Ages. And its compounds have been known to people for a long time; they were used to produce medicines and paints. Today, arsenic is used in a particularly versatile manner in metallurgy.

Historians called one of the periods of human development the bronze period. At this time, people switched from stone weapons to improved bronze weapons. Bronze is a compound ( alloy) tin with copper. According to historians, the first bronze was cast in the Tigris and Euphrates valley, around the 30th century. BC. Depending on the percentage composition of the components included in the alloy, bronze cast by different blacksmiths could have different properties. Scientists have found that the best bronze with valuable properties is a copper alloy that contains up to 3% tin and up to 7% arsenic substances. Such bronze was easy to cast and forged better. Probably, during smelting, copper ore was confused with weathering products of copper-arsenic sulfide minerals, which had a similar appearance. Ancient craftsmen appreciated the good properties of the alloy and then purposefully searched for deposits of arsenic minerals. To find them, we used the specific property of these minerals to give off a garlicky odor when heated. But over time, the smelting of bronze containing arsenic compounds ceased. Most likely, this happened due to the fact that poisoning very often occurred when firing arsenic-containing substances.

Of course, in the distant past this element was known only in the form of its minerals. In ancient China, they knew a solid mineral called realgar, which, as is now known, is a sulfide with the composition As4S4. Word " realgar" translated from Arabic means " mine dust" This mineral was used for stone carving, but it had one significant drawback: in the light or when heated, realgar “spoiled”, because under the influence of a thermal reaction it turned into a completely different substance, As2S3.

Scientist and philosopher Aristotle in the 4th century BC. gave its name to this mineral - “ sandarac" Three centuries later, the Roman scientist and writer Pliny the Elder together with a doctor and a botanist Dioscorides described another mineral called orpiment. The Latin name of the mineral is translated “ gold paint" This mineral was used as a yellow dye.

In the Middle Ages, alchemists isolated three forms of the substance: yellow arsenic ( being a sulfide of As2S3), red ( sulfide As4S4) and white ( oxide As2O3). White is formed by the sublimation of some arsenic impurities during the roasting of copper ores that contain this element. It condensed from the gas phase and settled in the form of a white coating, after which it was collected.

In the 13th century, alchemists heated yellow arsenic and soap to produce a metal-like substance that may have been the first example of a pure substance produced artificially. But the resulting substance violated the alchemists’ ideas about the mystical “connection” of the seven metals known to them with the seven astronomical objects - the planets; that is why alchemists called the resulting substance “illegitimate metal.” They noticed one interesting property about it - the substance could give copper a white color.

Arsenic was clearly identified as an independent substance at the beginning of the 17th century, when a pharmacist Johann Schröder when reducing the oxide with charcoal, I obtained it in its pure form. A few years later, a French physician and chemist Nicola Lemery managed to obtain this substance by heating its oxide in a mixture with potash and soap. In the next century it was already well known and called an unusual “semi-metal”.

Swedish scientist Scheele experimentally obtained arsenous hydrogen gas and arsenic acid. In the same time A.L. Lavoisier recognized this substance as an independent chemical element.

Being in natural conditions

The element is often found in natural conditions in compounds with copper, cobalt, nickel, and iron. There is not much of it in the earth's crust - about 5 grams per ton, which is about the same amount as tin, molybdenum, germanium, tungsten and bromine.

The composition of minerals that this chemical element forms ( today there are more than 200 of them), due to the “semi-metallic” properties of the element. It can be in both negative and positive oxidation states and therefore combines easily with many other elements; in positive oxidation, arsenic plays the role of a metal ( for example, in sulfides), if negative – non-metal ( in arsenides). Arsenic-containing minerals have a complex composition. The element itself can replace antimony, sulfur, and metal atoms in the crystal lattice.

Many compounds of metals and arsenic, judging by their composition, are more likely to be intermetallic compounds than arsenides; Some of them are distinguished by variable content of the main element. Several metals can be simultaneously present in arsenides, and the atoms of these metals, with close ion radii, can replace each other in the crystal lattice in arbitrary ratios. All minerals classified as arsenides have a metallic luster. They are opaque, heavy, and their hardness is low.

An example of natural arsenides ( there are approximately 25 of them) can serve such minerals as skutterudite, safflorite, rammelsbergite, nickelskutterudite, nickelin, löllingite, sperrylite, maucherite, algodonite, langisite, clinosafflorite. These arsenides have a high density and belong to the group of “superheavy” minerals.

The most common mineral is arsenopyrite ( or, as it is also called, arsenic pyrite). What seems interesting to chemists is the structure of those minerals in which arsenic is present simultaneously with sulfur, and in which it plays the role of a metal, since it is grouped together with other metals. These minerals are arsenosulvanite, gyrodite, arsenogauchekornite, freibergite, goldfieldite, tennantite, argentotennantite. The structure of these minerals is very complex.

Natural sulfides such as realgar, orpiment, dimorphite, getchellite, have a positive oxidation state As ( lat. arsenic designation). These minerals appear as small inclusions, although crystals of large size and weight have occasionally been mined in some areas.

An interesting fact is that natural salts of arsenic acid, called arsenates, look very different. Erythritol has a cobalt color, while scorodite, annabergite and simplesite are green. And görnesite, köttigitite, and rooseveltite are completely colorless.

In the central region of Sweden there are quarries in which ferromanganese ore is mined. More than fifty samples of minerals that are arsenates were found and described in these quarries. Some of these arsenates have not been found anywhere else. Experts believe that these minerals were formed at low temperatures as a result of the interaction of arsenic acid with other substances. Arsenates are oxidation products of certain sulfide ores. They usually have no value other than aesthetic value. Such minerals are decorations of mineralogical collections.

The names of the minerals were given in different ways: some of them were named after scientists and prominent political figures; others were named after the locality in which they were found; still others were named by Greek terms denoting their basic properties ( for example color); the fourth were named with abbreviations that denoted the initial letters of the names of other elements.

For example, the formation of the ancient name for such a mineral as nickel is interesting. Previously it was called kupfernickel. German miners who worked to develop copper five to six centuries ago were superstitiously afraid of an evil mountain spirit, which they called Nickel. German word " kupfer" meant " copper" They called “damn” or “fake” copper Kupfernickel. This ore was very similar to copper, but copper could not be obtained from it. But it has found its application in glass making. With its help, glass was painted green. Subsequently, a new metal was isolated from this ore and called nickel.

Pure arsenic is quite inert in its chemical properties and can be found in its native state. It looks like fused needles or cubes. Such a nugget is easy to grind into powder. It contains up to 15% impurities ( cobalt, iron, nickel, silver and other metals).

As a rule, the As content in soil ranges from 0.1 mg/kg to 40 mg/kg. In areas where arsenic ore occurs and in the area of ​​volcanoes, the soil can contain very large amounts of As - up to 8 g/kg. This is exactly the rate found in some areas of New Zealand and Switzerland. In such areas, flora dies and animals get sick. The same situation is typical for deserts and steppes, where arsenic is not washed out of the soil. Compared to the average content, clayey rocks are also considered enriched, since they contain four times more arsenic substances.

If a pure substance is converted as a result of biomethylation into a volatile organoarsenic compound, then it is carried out of the soil not only by water, but also by wind. Biomethylation is the addition of a methyl group to form a C–As bond. This process is carried out with the participation of the substance methylcobalamin - a methylated derivative of vitamin B12. Biomethylation of As occurs in both seawater and freshwater. This leads to the formation of organoarsenic compounds such as methylarsonic and dimethylarsinic acids.

In those areas where there is no specific pollution, the arsenic concentration is 0.01 μg/m3, and in industrial areas where power plants and factories are located, the concentration reaches a level of 1 μg/m3. In areas where industrial centers are located, arsenic deposition is intense and amounts to up to 40 kg/sq. km per year.

Volatile arsenic compounds, when their properties had not yet been fully studied, brought a lot of trouble to people. Mass poisonings were not uncommon even in the 19th century. But the doctors did not know the reasons for the poisoning. And the toxic substance was contained in green wallpaper paint and plaster. High humidity led to the formation of mold. Under the influence of these two factors, volatile organoarsenic substances were formed.

There is an assumption that the process of formation of volatile organoarsenic derivatives could have caused the delayed poisoning of the emperor Napoleon which led to his death. This assumption is based on the fact that 150 years after his death, traces of arsenic were found in his hair.

Arsenic substances are found in moderate quantities in some mineral waters. Generally accepted standards establish that in medicinal mineral waters the concentration of arsenic should be no more than 70 µg/l. In principle, even if the concentration of the substance is higher, it can lead to poisoning only with constant, long-term use.

Arsenic can be found in natural waters in various compounds and forms. Trivalent arsenic, for example, is many times more toxic than pentavalent arsenic.

Some seaweeds can accumulate arsenic in such concentrations that they are dangerous to humans. Such algae can easily grow and even reproduce in an acidic arsenic environment. In some countries they are used as pest control agents ( against rats).

Chemical properties

Arsenic is sometimes called a metal, but in reality it is more of a non-metal. It does not form salts when combined with acids, but in itself it is an acid-forming substance. That's why it is also called a semimetal. Like phosphorus, arsenic can exist in different allotropic forms.

One of these forms is gray arsenic, a rather fragile substance. Its fracture has a bright metallic sheen ( therefore, its second name is “arsenic metal”). The electrical conductivity of this semimetal is 17 times less than that of copper, but at the same time 3.6 times greater than that of mercury. The higher the temperature, the lower the electrical conductivity. This typical property of metals is also characteristic of this semimetal.

If arsenic vapor is cooled for a short time to a temperature of –196 degrees ( this is the temperature of liquid nitrogen), you will get a soft, transparent, yellow substance that looks like yellow phosphorus. The density of this substance is much lower than that of arsenic metal. Yellow arsenic and arsenic vapors consist of molecules that have the shape of a tetrahedron ( those. pyramid shape with four bases). Phosphorus molecules have the same shape.

Under the influence of ultraviolet radiation, as well as when heated, yellow arsenic instantly turns into gray; This reaction releases heat. If vapors condense in an inert atmosphere, then another form of this element is formed - amorphous. If arsenic vapor is deposited on glass, a mirror film is formed.

The structure of the electronic outer shell of this element is the same as that of phosphorus and nitrogen. Arsenic, like phosphorus, can form three covalent bonds.

If the air is dry, then As has a stable form. It becomes dull from humid air and becomes covered with black oxide on top. When ignited, arsenic vapor easily burns with a blue flame.

As in its pure form is quite inert; alkalis, water and various acids that do not have oxidizing properties do not affect it in any way. If you take dilute nitric acid, it will oxidize pure As to orthoarsenous acid, and if you take concentrated nitric acid, it will oxidize it to orthoarsenous acid.

As reacts with sulfur and halogens. In reactions with sulfur, sulfides of different compositions are formed.

Arsenic is like poison

All arsenic compounds are poisonous.

Acute poisoning by these substances is manifested by abdominal pain, diarrhea, vomiting, and central nervous system depression. The symptoms of intoxication with this substance are very similar to the symptoms of cholera. Therefore, in judicial practice, cases of the use of arsenic as a poison were often encountered in the past. The most successfully used poisonous compound for criminal purposes is arsenic trioxide.

In those areas where there is an excess of the substance in water and soil, it accumulates in the thyroid glands of people. As a result, they develop an endemic goiter.

Arsenic poisoning

Symptoms of arsenic poisoning include a metallic taste in the mouth, vomiting, and severe abdominal pain. Later, seizures or paralysis may occur. Poisoning can lead to death. The most widely available and well-known antidote for arsenic intoxication is milk. The main protein of milk is casein. It forms an insoluble compound with arsenic that is not absorbed into the blood.

Poisoning occurs:
1. When inhaling arsenic compounds in the form of dust ( most often - in unfavorable production conditions).
2. When drinking poisoned water and food.
3. When using certain medications. Excess substance is deposited in the bone marrow, lungs, kidneys, skin, and intestinal tract. There is a large body of evidence that inorganic arsenic compounds are carcinogenic. Due to long-term consumption of arsenic-poisoned water or medications, low-grade skin cancer may develop ( Bowen's cancer) or liver hemangioendothelioma.

In case of acute poisoning, gastric lavage is required as first aid. In stationary conditions, hemodialysis is performed to cleanse the kidneys. For use in acute and chronic poisoning, Unithiol is used - a universal antidote. Additionally, antagonist substances are used: sulfur, selenium, zinc, phosphorus; and a complex of vitamins and amino acids is mandatory.

Symptoms of overdose and deficiency

Possible signs of arsenic deficiency are manifested by a decrease in the concentration of triglycerides in the blood, an increase in fertility, and a deterioration in the development and growth of the body.

Arsenic is a highly toxic substance; a single dose of 50 mg can be fatal. An overdose is manifested by irritability, allergies, headaches, dermatitis, eczema, conjunctivitis, depression of respiratory function and the nervous system, and impaired liver function. An overdose of a substance increases the risk of developing cancer.

The source of the element is considered to be: plant and animal products, seafood, grains, cereals, tobacco, wine, and even drinking water.

There is no need to worry about getting this microelement into our diet - it is found in almost all products of animal and plant origin, except in refined sugar. It comes to us in sufficient quantities with food. Products especially rich in it, such as shrimp, lobster, lobsters - in order to avoid an overdose, you should eat in moderation so as not to ingest an excessive amount of poison.

Arsenic compounds can enter the human body with mineral water, seafood, juices, grape wines, medications, herbicides and pesticides. This substance accumulates mainly in the reticuloendothelial system, as well as in the lungs, skin, and kidneys. An insufficient daily intake of a substance into the body is considered to be 1 mcg/day. The toxicity threshold is approximately 20 mg.

A large amount of the element is found in fish oil and, oddly enough, in wines. In normal drinking water, the content of the substance is low and not hazardous to health - approximately 10 µg/l. Some regions of the world ( Mexico, Taiwan, India, Bangladesh) are notorious for having high levels of arsenic in their drinking water ( 1 mg/l), and therefore mass poisonings of citizens sometimes occur there.

Arsenic prevents the body from losing phosphorus. Vitamin D is a regulating factor in the course of phosphorus-calcium metabolism, and arsenic, in turn, regulates phosphorus metabolism.

It is also known that some forms of allergies develop due to arsenic deficiency in the body.

The trace element is used to increase appetite in case of anemia. For selenium poisoning, arsenic is an excellent antidote. Experimental studies on mice have shown that precisely calculated doses of the substance help reduce the incidence of cancer.

When the concentration of an element in soil or food increases, intoxication occurs. Severe intoxication can lead to serious diseases such as laryngeal cancer or leukemia. Moreover, the number of deaths will also increase.

It is known that 80% of the substance that enters the body with food is sent to the gastrointestinal tract and from there enters the blood, and the remaining 20% ​​reaches us through the skin and lungs.

A day after entering the body, more than 30% of the substance is excreted from it along with urine and about 4% along with feces. According to the classification, arsenic is classified as an immunotoxic, conditionally essential, element. It has been proven that the substance takes part in almost all important biochemical processes.

Arsenic in dentistry

This substance is often used to treat dental diseases such as caries. Caries begins when the calcareous salts of tooth enamel begin to break down and the weakened tooth is attacked by pathogens. By affecting the soft inner part of the tooth, microbes form a carious cavity.
If at this stage of the disease the carious cavity is cleaned and filled with filling material, the tooth will remain “alive”. And if you let the process take its course, the carious cavity reaches the tissue that contains blood, nerve and lymphatic vessels. It's called pulp.

Inflammation of the pulp develops, after which the only way to prevent further spread of the disease is to remove the nerve. It is for this manipulation that arsenic is needed.

The pulp is exposed with a dental instrument, a grain of paste containing arsenous acid is placed on it, and it diffuses into the pulp almost instantly. A day later the tooth dies. Now the pulp can be removed completely painlessly, the root canals and pulp chamber can be filled with a special antiseptic paste, and the tooth can be sealed.

Arsenic in the treatment of leukemia

Arsenic is quite successfully used to treat mild forms of leukemia, as well as during the period of primary exacerbation, in which a sharp enlargement of the spleen and lymph nodes has not yet been observed. It reduces or even suppresses the pathological formation of leukocytes, stimulates red hematopoiesis and the release of red blood cells to the periphery.

Obtaining arsenic

It is obtained as a by-product of the processing of lead, copper, cobalt and zinc ores, as well as during gold mining. Some of the polymetallic ores contain up to 12% arsenic. If they are heated to 650 - 700 degrees, then in the absence of air sublimation occurs. If heated in air, “white arsenic” is formed, which is a volatile oxide. It is condensed and heated with coal, during which arsenic is reduced. Obtaining this element is a harmful production.

Previously, before the development of ecology as a science, “white arsenic” was released into the atmosphere in large quantities, and subsequently it settled on trees and plants. The permissible concentration in the air is 0.003 mg/m3, while near industrial facilities the concentration reaches 200 mg/m3. Oddly enough, the environment is most polluted not by those factories that produce arsenic, but by power plants and non-ferrous metallurgy enterprises. Bottom sediments near copper smelters contain large amounts of the element - up to 10 g/kg.

Another paradox is that this substance is produced in greater quantities than it is required. This is a rare occurrence in the metal mining industry. Excess it has to be disposed of in large metal containers, hiding them in disused old mines.

Arsenopyrite is a valuable industrial mineral. Large copper-arsenic deposits are found in Central Asia, Georgia, USA, Japan, Norway, Sweden; gold-arsenic - in the USA, France; arsenic-cobalt - in New Zealand, Canada; arsenic-tin - in England and Bolivia.

Determination of arsenic

The qualitative reaction to arsenic consists of the precipitation of yellow sulfides from hydrochloric acid solutions. Traces are determined by the Gutzeit method or the Marsh reaction: paper strips soaked in HgCl2 change color to dark in the presence of arsine, which reduces sublimate to mercury.

Over the past half century, a variety of sensitive analytical techniques have been developed ( spectrometry), thanks to which even small amounts of arsenic can be detected. If there is very little substance in the water, then the samples are pre-concentrated.

Some compounds are analyzed by the selective hydride method. This method involves selective reduction of the analyte to the volatile compound arsine. Volatile arsines are frozen in a container cooled with liquid nitrogen. Then, by slowly heating the contents of the container, you can ensure that different arsines evaporate separately from each other.

Industrial Application

About 98% of all arsenic mined is not used in its pure form. But its compounds have gained popularity and are used in various industries. Hundreds of tons of the substance are mined and used annually. It is added to bearing alloys to improve quality, used in the creation of cables and lead batteries to increase hardness, and used in alloys with germanium or silicon in the production of semiconductor devices. Arsenic is used as a dopant that imparts a certain type of conductivity to “classical” semiconductors.

Arsenic is a valuable material in non-ferrous metallurgy. When added to lead in an amount of 1%, the hardness of the alloy increases. If you add a little arsenic to molten lead, then in the process of casting the shot, spherical balls of regular shape come out. Additives to copper enhance its strength, corrosion resistance and hardness. Thanks to this additive, the fluidity of copper increases, which facilitates the process of wire drawing.

As is added to some types of brass, bronze, printing alloys, and babbitts. But still, metallurgists are trying to exclude this additive from the production process, since it is very harmful to humans. Moreover, it is also harmful to metals, since the presence of arsenic in large quantities impairs the properties of many alloys and metals.

Oxides are used in glass making as glass brighteners. Even ancient glassblowers knew that white arsenic contributes to the opacity of glass. However, small additions of it, on the contrary, brighten the glass. Arsenic is still included in the recipe for making some glasses, for example, “Vienna” glass, used to create thermometers.

Arsenic compounds are used as an antiseptic to protect against spoilage, as well as for preserving furs, skins, stuffed animals; for creating antifouling paints for water transport; for impregnation of wood.

The biological activity of some As derivatives has interested agronomists, sanitary and epidemiological service workers, and veterinarians. As a result, arsenic-containing drugs were created, which were stimulants of productivity and growth; medicines for the prevention of livestock diseases; anthelmintic agents.

Landowners in ancient China treated rice crops with arsenic oxide to protect them from fungal diseases and rats, and thus protect the crop. Now, due to the toxicity of arsenic-containing substances, their use in agriculture is limited.

The most important areas of use of arsenic-containing substances are the production of microcircuits, semiconductor materials and fiber optics, film electronics, as well as the growth of special single crystals for lasers. In these cases, as a rule, gaseous arsine is used. Indium and gallium arsenides are used in the manufacture of diodes, transistors, and lasers.

In tissues and organs, the element is mainly found in the protein fraction, much less of it is in the acid-soluble fraction, and only a small part of it is in the lipid fraction. It is a participant in redox reactions; without it, the oxidative breakdown of complex carbohydrates is impossible. It is involved in fermentation and glycolysis. Compounds of this substance are used in biochemistry as specific enzyme inhibitors, which are needed to study metabolic reactions. It is necessary for the human body as a trace element.

Arsenic is a chemical element of the nitrogen group (group 15 of the periodic table). This is a gray, metallic, brittle substance (α-arsenic) with a rhombohedral crystal lattice. When heated to 600°C, As sublimates. When the vapor is cooled, a new modification appears - yellow arsenic. Above 270°C, all forms of As transform into black arsenic.

History of discovery

What arsenic was was known long before it was recognized as a chemical element. In the 4th century. BC e. Aristotle mentioned a substance called sandarac, which is now believed to have been realgar, or arsenic sulfide. And in the 1st century AD. e. the writers Pliny the Elder and Pedanius Dioscorides described orpiment - the dye As 2 S 3. In the 11th century n. e. There were three varieties of “arsenic”: white (As 4 O 6), yellow (As 2 S 3) and red (As 4 S 4). The element itself was probably first isolated in the 13th century by Albertus Magnus, who noted the appearance of a metal-like substance when arsenicum, another name for As 2 S 3, was heated with soap. But there is no certainty that this natural scientist obtained pure arsenic. The first authentic evidence of pure isolation dates back to 1649. German pharmacist Johann Schröder prepared arsenic by heating its oxide in the presence of coal. Later, Nicolas Lemery, a French physician and chemist, observed the formation of this chemical element by heating a mixture of its oxide, soap and potash. By the beginning of the 18th century, arsenic was already known as a unique semimetal.

Prevalence

In the earth's crust, the concentration of arsenic is low and amounts to 1.5 ppm. It is found in soil and minerals and can be released into the air, water and soil through wind and water erosion. In addition, the element enters the atmosphere from other sources. As a result of volcanic eruptions, about 3 thousand tons of arsenic are released into the air per year, microorganisms produce 20 thousand tons of volatile methylarsine per year, and as a result of the combustion of fossil fuels, 80 thousand tons are released over the same period.

Despite the fact that As is a deadly poison, it is an important component of the diet of some animals and, possibly, humans, although the required dose does not exceed 0.01 mg/day.

Arsenic is extremely difficult to convert into a water-soluble or volatile state. The fact that it is quite mobile means that large concentrations of the substance cannot appear in any one place. On the one hand, this is a good thing, but on the other hand, the ease with which it spreads is why arsenic contamination is becoming a bigger problem. Due to human activity, mainly through mining and smelting, the normally immobile chemical element migrates and can now be found in places other than its natural concentration.

The amount of arsenic in the earth's crust is about 5 g per ton. In space, its concentration is estimated to be 4 atoms per million silicon atoms. This element is widespread. A small amount of it is present in the native state. As a rule, arsenic formations with a purity of 90-98% are found together with metals such as antimony and silver. Most of it, however, is included in more than 150 different minerals - sulfides, arsenides, sulfoarsenides and arsenites. Arsenopyrite FeAsS is one of the most common As-containing minerals. Other common arsenic compounds are the minerals realgar As 4 S 4, orpiment As 2 S 3, lellingite FeAs 2 and enargite Cu 3 AsS 4. Arsenic oxide is also common. Most of this substance is a by-product of the smelting of copper, lead, cobalt and gold ores.

In nature, there is only one stable isotope of arsenic - 75 As. Among the artificial radioactive isotopes, 76 As with a half-life of 26.4 hours stands out. Arsenic-72, -74 and -76 are used in medical diagnostics.

Industrial production and application

Metallic arsenic is obtained by heating arsenopyrite to 650-700 °C without air access. If arsenopyrite and other metal ores are heated with oxygen, then As easily combines with it, forming easily sublimated As 4 O 6, also known as “white arsenic”. The oxide vapor is collected and condensed, and later purified by repeated sublimation. Most As is produced by its reduction with carbon from white arsenic thus obtained.

Global consumption of arsenic metal is relatively small - only a few hundred tons per year. Most of what is consumed comes from Sweden. It is used in metallurgy due to its metalloid properties. About 1% arsenic is used in the production of lead shot as it improves the roundness of the molten drop. The properties of lead-based bearing alloys improve both thermally and mechanically when they contain about 3% arsenic. The presence of small amounts of this chemical element in lead alloys hardens them for use in batteries and cable armor. Small arsenic impurities increase the corrosion resistance and thermal properties of copper and brass. In its pure form, the chemical elemental As is used for bronze coating and in pyrotechnics. Highly purified arsenic has applications in semiconductor technology, where it is used with silicon and germanium, and in the form of gallium arsenide (GaAs) in diodes, lasers and transistors.

As connections

Since the valency of arsenic is 3 and 5, and it has a range of oxidation states from -3 to +5, the element can form different types of compounds. Its most important commercially important forms are As 4 O 6 and As 2 O 5 . Arsenic oxide, commonly known as white arsenic, is a byproduct of roasting ores of copper, lead and some other metals, as well as arsenopyrite and sulfide ores. It is the starting material for most other compounds. It is also used in pesticides, as a decolorizing agent in glass production, and as a preservative for leathers. Arsenic pentoxide is formed when white arsenic is exposed to an oxidizing agent (such as nitric acid). It is the main ingredient in insecticides, herbicides and metal adhesives.

Arsine (AsH 3), a colorless poisonous gas composed of arsenic and hydrogen, is another known substance. The substance, also called arsenic hydrogen, is obtained by hydrolysis of metal arsenides and reduction of metals from arsenic compounds in acid solutions. It has found use as a dopant in semiconductors and as a chemical warfare agent. In agriculture, arsenic acid (H 3 AsO 4), lead arsenate (PbHAsO 4) and calcium arsenate [Ca 3 (AsO 4) 2], which are used for soil sterilization and pest control, are of great importance.

Arsenic is a chemical element that forms many organic compounds. Cacodyne (CH 3) 2 As−As(CH 3) 2, for example, is used in the preparation of the widely used desiccant (drying agent) cacodylic acid. Complex organic compounds of the element are used in the treatment of certain diseases, for example, amoebic dysentery caused by microorganisms.

Physical properties

What is arsenic in terms of its physical properties? In its most stable state, it is a brittle, steel-gray solid with low thermal and electrical conductivity. Although some forms of As are metal-like, classifying it as a nonmetal is a more accurate characterization of arsenic. There are other forms of arsenic, but they are not very well studied, especially the yellow metastable form, consisting of As 4 molecules, like white phosphorus P 4 . Arsenic sublimes at a temperature of 613 °C, and in the form of vapor it exists as As 4 molecules, which do not dissociate until a temperature of about 800 °C. Complete dissociation into As 2 molecules occurs at 1700 °C.

Atomic structure and ability to form bonds

The electronic formula of arsenic - 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 3 - resembles nitrogen and phosphorus in that there are five electrons in the outer shell, but it differs from them in having 18 electrons in the penultimate shell instead of two or eight. Adding 10 positive charges to the nucleus while filling the five 3d orbitals often causes an overall decrease in the electron cloud and an increase in the electronegativity of the elements. Arsenic in the periodic table can be compared with other groups that clearly demonstrate this pattern. For example, it is generally accepted that zinc is more electronegative than magnesium, and gallium than aluminum. However, in subsequent groups this difference decreases, and many do not agree that germanium is more electronegative than silicon, despite the abundance of chemical evidence. A similar transition from the 8- to 18-element shell from phosphorus to arsenic may increase electronegativity, but this remains controversial.

The similarity of the outer shell of As and P suggests that they can form 3 per atom in the presence of an additional unbonded electron pair. The oxidation state must therefore be +3 or -3, depending on the relative mutual electronegativity. The structure of arsenic also suggests the possibility of using the outer d-orbital to expand the octet, which allows the element to form 5 bonds. It is realized only when reacting with fluorine. The presence of a free electron pair for the formation of complex compounds (through electron donation) in the As atom is much less pronounced than in phosphorus and nitrogen.

Arsenic is stable in dry air, but turns into a black oxide in humid air. Its vapors burn easily, forming As 2 O 3. What is free arsenic? It is practically unaffected by water, alkalis and non-oxidizing acids, but is oxidized by nitric acid to a state of +5. Halogens and sulfur react with arsenic, and many metals form arsenides.

Analytical chemistry

The substance arsenic can be qualitatively detected in the form of yellow orpiment, which precipitates under the influence of a 25% solution of hydrochloric acid. Traces of As are typically determined by converting it to arsine, which can be detected using the Marsh test. Arsine thermally decomposes to form a black mirror of arsenic inside a narrow tube. According to the Gutzeit method, a sample impregnated with arsine darkens due to the release of mercury.

Toxicological characteristics of arsenic

The toxicity of the element and its derivatives varies widely, from the extremely toxic arsine and its organic derivatives to simply As, which is relatively inert. What arsenic is is evidenced by the use of its organic compounds as chemical warfare agents (lewisite), vesicant and defoliant (Agent Blue based on an aqueous mixture of 5% cacodylic acid and 26% of its sodium salt).

In general, derivatives of this chemical element irritate the skin and cause dermatitis. Protection from inhalation of arsenic-containing dust is also recommended, but most poisoning occurs through ingestion. The maximum permissible concentration of As in dust over an eight-hour working day is 0.5 mg/m 3 . For arsine, the dose is reduced to 0.05 ppm. In addition to the use of compounds of this chemical element as herbicides and pesticides, the use of arsenic in pharmacology made it possible to obtain salvarsan, the first successful drug against syphilis.

Health effects

Arsenic is one of the most toxic elements. Inorganic compounds of this chemical occur naturally in small quantities. People can be exposed to arsenic through food, water, and air. Exposure may also occur through skin contact with contaminated soil or water.

People who work with it, live in homes built from wood treated with it, and on agricultural lands where pesticides have been used in the past are also susceptible to exposure.

Inorganic arsenic can cause a variety of health effects in humans, such as stomach and intestinal irritation, decreased production of red and white blood cells, skin changes, and lung irritation. It is suspected that ingesting significant amounts of this substance may increase the chances of developing cancer, especially cancer of the skin, lungs, liver and lymphatic system.

Very high concentrations of inorganic arsenic cause infertility and miscarriages in women, dermatitis, decreased body resistance to infections, heart problems and brain damage. In addition, this chemical element can damage DNA.

The lethal dose of white arsenic is 100 mg.

Organic compounds of the element do not cause cancer or damage to the genetic code, but high doses can harm human health, for example, cause nervous disorders or abdominal pain.

Properties As

The main chemical and physical properties of arsenic are as follows:

• Atomic number is 33.
• Atomic weight - 74.9216.
• The melting point of the gray form is 814 °C at a pressure of 36 atmospheres.
• The density of the gray form is 5.73 g/cm 3 at 14 °C.
• The density of the yellow form is 2.03 g/cm 3 at 18 °C.
• The electronic formula of arsenic is 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 3.
• Oxidation states - -3, +3, +5.
• The valency of arsenic is 3.5.