• Designation - P (Phosphorus);
• Period - III;
• Group - 15 (Va);
• Atomic mass - 30.973761;
• Atomic number - 15;
• Atomic radius = 128 pm;
• Covalent radius = 106 pm;
• Electron distribution - 1s 2 2s 2 2p 6 3s 2 3p 3 ;
• melting temperature = 44.14°C;
• boiling point = 280°C;
• Electronegativity (according to Pauling/according to Alpred and Rochow) = 2.19/2.06;
• Oxidation state: +5, +3, +1, 0, -1, -3;
• Density (no.) = 1.82 g/cm 3 (white phosphorus);
• Molar volume = 17.0 cm 3 /mol.

Phosphorus compounds:

Phosphorus (the bringer of light) was first obtained by the Arab alchemist Ahad Behil in the 12th century. Of the European scientists, the first to discover phosphorus was the German Hennig Brant in 1669, while conducting experiments with human urine in an attempt to extract gold from it (the scientist believed that the golden color of urine was caused by the presence of gold particles). Somewhat later, phosphorus was obtained by I. Kunkel and R. Boyle - the latter described it in his article “Method of preparing phosphorus from human urine” (October 14, 1680; the work was published in 1693). Lavoisier later proved that phosphorus is a simple substance.

The phosphorus content in the earth's crust is 0.08% by weight - this is one of the most common chemical elements on our planet. Due to its high activity, phosphorus in a free state does not occur in nature, but is part of almost 200 minerals, the most common of which are apatite Ca 5 (PO 4) 3 (OH) and phosphorite Ca 3 (PO 4) 2.

Phosphorus plays an important role in the life of animals, plants and humans - it is part of such biological compounds as phospholipids, and is also present in proteins and other important organic compounds such as DNA and ATP.

Rice. The structure of the phosphorus atom.

The phosphorus atom contains 15 electrons and has an electronic configuration of the outer valence level similar to nitrogen (3s 2 3p 3), but phosphorus has less pronounced nonmetallic properties compared to nitrogen, which is explained by the presence of a free d-orbital, a larger atomic radius and lower ionization energy .

When reacting with other chemical elements, the phosphorus atom can exhibit an oxidation state from +5 to -3 (the most typical oxidation state is +5, the rest are quite rare).

• +5 - phosphorus oxide P 2 O 5 (V); phosphoric acid (H 3 PO 4); phosphates, halides, sulfides of phosphorus V (salts of phosphoric acid);
• +3 - P 2 O 3 (III); phosphorous acid (H 3 PO 3); phosphites, halides, sulfides of phosphorus III (salts of phosphorous acid);
• 0 - P;
• -3 - phosphine PH 3; metal phosphides.

In the ground (unexcited) state of the phosphorus atom at the outer energy level there are two paired electrons in the s-sublevel + 3 unpaired electrons in p-orbitals (the d-orbital is free). In the excited state, one electron moves from the s-sublevel to the d-orbital, which expands the valence capabilities of the phosphorus atom.

Rice. Transition of the phosphorus atom to an excited state.

P2

Two phosphorus atoms combine to form a P2 molecule at a temperature of about 1000°C.

At lower temperatures, phosphorus exists in tetraatomic P4 molecules as well as in more stable polymer P∞ molecules.

Allotropic modifications of phosphorus:

• White phosphorus- extremely toxic (the lethal dose of white phosphorus for an adult is 0.05-0.15 g) waxy substance with the smell of garlic, colorless, luminescent in the dark (the process of slow oxidation in P 4 O 6); the high reactivity of white phosphorus is explained by weak P-P bonds (white phosphorus has a molecular crystal lattice with the formula P 4, in the nodes of which phosphorus atoms are located), which break quite easily, as a result of which white phosphorus, when heated or during long-term storage, turns into more stable polymer modifications: red and black phosphorus. For these reasons, white phosphorus is stored without access to air under a layer of purified water or in special inert environments.
• Yellow phosphorus- a flammable, highly toxic substance, does not dissolve in water, easily oxidizes in air and ignites spontaneously, while burning with a bright green, dazzling flame with the release of thick white smoke.
• Red phosphorus- a polymeric, water-insoluble substance with a complex structure that has the least reactivity. Red phosphorus is widely used in industrial production, because it is not so poisonous. Since in the open air red phosphorus, absorbing moisture, gradually oxidizes to form a hygroscopic oxide (“damp”) and forms viscous phosphoric acid, therefore, red phosphorus is stored in a hermetically sealed container. In the case of soaking, red phosphorus is cleaned of phosphoric acid residues by washing with water, then dried and used for its intended purpose.
• Black phosphorus- a greasy-to-touch graphite-like substance of gray-black color, with semiconductor properties - the most stable modification of phosphorus with average reactivity.
• Metallic phosphorus obtained from black phosphorus under high pressure. Metallic phosphorus conducts electricity very well.

Chemical properties of phosphorus

Of all the allotropic modifications of phosphorus, the most active is white phosphorus (P 4). Often in the equation of chemical reactions we write simply P, not P4. Since phosphorus, like nitrogen, has many variants of oxidation states, in some reactions it is an oxidizing agent, in others it is a reducing agent, depending on the substances with which it interacts.

Oxidative Phosphorus exhibits its properties in reactions with metals that occur when heated to form phosphides:
3Mg + 2P = Mg 3 P 2.

Phosphorus is reducing agent in reactions:

• with more electronegative nonmetals (oxygen, sulfur, halogens):
  • Phosphorus (III) compounds are formed when there is a lack of oxidizing agent
    4P + 3O 2 = 2P 2 O 3
  • phosphorus compounds (V) - with excess: oxygen (air)
    4P + 5O 2 = 2P 2 O 5
• with halogens and sulfur, phosphorus forms halides and sulfide of 3- or 5-valent phosphorus, depending on the ratio of reagents, which are taken in deficiency or excess:
  • 2P+3Cl 2 (week) = 2PCl 3 - phosphorus (III) chloride
  • 2P+3S(week) = P 2 S 3 - phosphorus (III) sulfide
  • 2P+5Cl2(g) = 2PCl 5 - phosphorus chloride (V)
  • 2P+5S(g) = P 2 S 5 - phosphorus sulfide (V)
• with concentrated sulfuric acid:
  2P+5H 2 SO 4 = 2H 3 PO 4 +5SO 2 +2H 2 O
• with concentrated nitric acid:
  P+5HNO 3 = H 3 PO 4 +5NO 2 +H 2 O
• with dilute nitric acid:
  3P+5HNO 3 +2H 2 O = 3H 3 PO 4 +5NO

Phosphorus acts as both an oxidizing agent and a reducing agent in reactions disproportionation with aqueous solutions of alkalis when heated, forming (except for phosphine) hypophosphites (salts of hypophosphorous acid), in which it exhibits an uncharacteristic oxidation state of +1:
4P 0 +3KOH+3H 2 O = P -3 H 3 +3KH 2 P +1 O 2

YOU MUST REMEMBER: phosphorus does not react with other acids, except for the reactions indicated above.

Production and use of phosphorus

Phosphorus is produced industrially by reducing it with coke from phosphorites (fluorapatates), which include calcium phosphate, by calcining them in electric furnaces at a temperature of 1600°C with the addition of quartz sand:
Ca 3 (PO 4) 2 + 5C + 3SiO 2 = 3CaSiO 3 + 2P + 5CO.

In the first stage of the reaction, under the influence of high temperature, silicon (IV) oxide displaces phosphorus (V) oxide from the phosphate:
Ca 3 (PO 4) 2 + 3SiO 2 = 3CaSiO 3 + P 2 O 5.

Phosphorus (V) oxide is then reduced by coal to free phosphorus:
P 2 O 5 +5C = 2P+5CO.

Application of phosphorus:

• pesticides;
• matches;
• detergents;
• paints;
• semiconductors.

Phosphorus (from the Greek phosphoros - luminiferous; lat. Phosphorus) is an element of the periodic system of chemical elements of the periodic table, one of the most common elements of the earth's crust, its content is 0.08-0.09% of its mass. Concentration in seawater is 0.07 mg/l. It is not found in a free state due to its high chemical activity. It forms about 190 minerals, the most important of which are apatite Ca 5 (PO 4) 3 (F,Cl,OH), phosphorite Ca 3 (PO 4) 2 and others. Phosphorus is found in all parts of green plants, even more in fruits and seeds (see phospholipids). Contained in animal tissues, it is part of proteins and other essential organic compounds (ATP, DNA), and is an element of life.

Story

Phosphorus was discovered by the Hamburg alchemist Hennig Brand in 1669. Like other alchemists, Brand tried to find the philosopher's stone, but received a luminous substance. Brand focused on experiments with human urine because he believed that, being golden in color, it might contain gold or something useful for mining. Initially, his method was to first let the urine sit for several days until the unpleasant odor disappeared, and then boil it until it became sticky. By heating this paste to high temperatures and causing bubbles to appear, he hoped that when they condensed, they would contain gold. After several hours of intense boiling, grains of a white wax-like substance were obtained, which burned very brightly and also shimmered in the dark. Brand named this substance phosphorus mirabilis (Latin for “miraculous bearer of light”). Brand's discovery of phosphorus was the first discovery of a new element since antiquity.
Somewhat later, phosphorus was obtained by another German chemist, Johann Kunkel.
Regardless of Brand and Kunkel, phosphorus was obtained by R. Boyle, who described it in the article “Method of preparing phosphorus from human urine,” dated October 14, 1680 and published in 1693.
An improved method for producing phosphorus was published in 1743 by Andreas Marggraf.
There is evidence that Arab alchemists were able to obtain phosphorus in the 12th century.
Lavoisier proved that phosphorus is a simple substance.

origin of name

In 1669, Henning Brand, by heating a mixture of white sand and evaporated urine, obtained a substance that glowed in the dark, first called “cold fire.” The secondary name “phosphorus” comes from the Greek words “φῶς” - light and “φέρω” - carry. In ancient Greek mythology, the name Phosphorus (or Eosphorus, ancient Greek Φωσφόρος) was borne by the guardian of the Morning Star.

Receipt

Phosphorus is obtained from apatites or phosphorites as a result of interaction with coke and silica at a temperature of 1600 ° C:
2Ca 3 (PO 4) 2 + 10C + 6SiO 2 → P4 + 10CO + 6CaSiO 3.

The resulting white phosphorus vapors are condensed in a receiver under water. Instead of phosphorites, other compounds can be reduced, for example, metaphosphoric acid:
4HPO 3 + 12C → 4P + 2H 2 + 12CO.

Physical properties

Elemental phosphorus under normal conditions represents several stable allotropic modifications; The issue of phosphorus allotropy is complex and not fully resolved. Usually there are four modifications of a simple substance - white, red, black and metallic phosphorus. Sometimes they are also called the main allotropic modifications, implying that all the others are a variety of these four. Under normal conditions, there are only three allotropic modifications of phosphorus, and under ultra-high pressure conditions there is also a metallic form. All modifications differ in color, density and other physical characteristics; There is a noticeable tendency towards a sharp decrease in chemical activity during the transition from white to metallic phosphorus and an increase in metallic properties.

Chemical properties

The chemical activity of phosphorus is much higher than that of nitrogen. The chemical properties of phosphorus are largely determined by its allotropic modification. White phosphorus is very active; in the process of transition to red and black phosphorus, the chemical activity decreases sharply. White phosphorus glows in the dark in air; the glow is due to the oxidation of phosphorus vapor to lower oxides.
In liquid and dissolved states, as well as in vapors up to 800 ° C, phosphorus consists of P 4 molecules. When heated above 800 °C, the molecules dissociate: P 4 = 2P 2. At temperatures above 2000 °C, molecules break down into atoms.

PHOSPHORUS, P (lat. Phosphorus * a. phosphorus; n. Phosphor; f. phosphore; i. fosforo), is a chemical element of group V of the periodic system of Mendeleev, atomic number 15, atomic mass 30.97376. Natural phosphorus is represented by one stable isotope 31 R. There are 6 known artificial radioactive isotopes of phosphorus with mass numbers 28-30 and 32-34.

The method of obtaining phosphorus may have been known to Arab alchemists as early as the 12th century, but the generally accepted date for the discovery of phosphorus is 1669, when H. Brand () obtained a substance that glowed in the dark, called “cold fire”. The existence of phosphorus as a chemical element was proven in the early 70s. 18th century French chemist A. Lavoisier.

Modifications and properties

Elemental phosphorus exists in the form of several allotropic modifications - white, red, black. White phosphorus is a waxy, transparent substance with a characteristic odor, formed by the condensation of phosphorus vapor. In the presence of impurities - traces of red phosphorus, arsenic, iron, etc. - it is colored yellow, therefore commercial white phosphorus is called yellow. There are 2 modifications of white phosphorus: a-P has a densely packed cubic lattice a = 0.185 nm; density 1828 kg/m3; melting point 44.2°C, boiling point 277°C; thermal conductivity 0.56 W/(m.K); molar heat capacity 23.82 J/(mol.K); temperature coefficient of linear expansion 125.10 -6 K -1 ; In terms of electrical properties, white phosphorus is close to dielectrics. At a temperature of 77.8°C and a pressure of 0.1 MPa, a-P transforms into b-P (rhombic lattice, density 1880 kg/m 3). Heating white phosphorus without air access at 250-300°C for several hours leads to the formation of a red modification. Ordinary commercial red phosphorus is practically amorphous, but upon prolonged heating it can transform into one of the crystalline forms (triclinic, cubic) with a density of 2000 to 2400 kg/m 3 and a melting point of 585-610°C. During sublimation (sublimation temperature 431°C), red phosphorus turns into gas, upon cooling of which mainly white phosphorus is formed. When white phosphorus is heated to 200-220°C under a pressure of 1.2-1.7 GPa, black phosphorus is formed. This type of transformation can be carried out at normal pressure (at 370°C), using as a catalyst, as well as a small amount of black phosphorus for seeding. Black phosphorus is a crystalline substance with a rhombic lattice (a=0.331, b=0.438 and c=1.05 nm), density 2690 kg/m 3, melting point 1000 °C; similar in appearance to graphite; semiconductor, diamagnetic. When heated to a temperature of 560-580°C and saturated vapor pressure, it turns into red phosphorus.

Chemical phosphorus

Phosphorus atoms combine into diatomic (P 2) and tetraatomic (P 4) polymer molecules. The most stable molecules under normal conditions are those containing long chains of interconnected P4 tetrahedra. In compounds, phosphorus has an oxidation state of +5, +3, -3. Like nitrogen in chemical compounds, it forms mainly a covalent bond. Phosphorus is a chemically active element. Its white modification is characterized by the greatest activity, which spontaneously ignites at a temperature of about 40°C, therefore it is stored under a layer of water. Red phosphorus ignites when struck or rubbed. Black phosphorus is inactive and difficult to ignite when ignited. Phosphorus oxidation is usually accompanied by chemiluminescence. When phosphorus burns in an excess of oxygen, P 2 O 5 is formed, and when there is a deficiency, mainly P 2 O 3 is formed. Phosphorus forms acids: ortho- (H 3 PO 4), polyphosphoric (H n + 2 PO 3n + 1), phosphorous (H 3 PO 3), phosphorous (H 4 P 2 O 6), phosphorous (H 3 PO 2) , as well as peracids: perphosphoric (H 4 P 2 O 8) and monoperphosphoric (H 3 PO 5).

Phosphorus reacts directly with all halogens, releasing large amounts of heat. Phosphorus sulfides and nitrides are known. At a temperature of 2000°C, phosphorus reacts with carbon, forming carbide (PC 3); when phosphorus is heated with metals - phosphides. White phosphorus and its compounds are highly toxic, MPC 0.03 mg/m3.

Phosphorus in nature

The average phosphorus content in the earth's crust (clarke) is 9.3.10 -2%, in ultrabasic rocks it is 1.7. 10 -2%, basic - 1.4.10 -2%, acidic - 7.10 -2%, sedimentary - 7.7.10 -2%. Phosphorus is involved in magmatic processes and migrates vigorously in the biosphere. Both processes are associated with its large accumulations, forming industrial deposits of apatites - Ca 5 (PO 4) 3 (F, Cl) and phosphorites - amorphous Ca 5 (PO 4) 3 (OH, CO 3) with various impurities. Phosphorus is an extremely important biogenic element that is accumulated by many organisms. The processes of phosphorus concentration in the earth's crust are associated with biogenic migration. Over 180 minerals containing phosphorus are known.

Receipt and use

On an industrial scale, phosphorus is extracted from natural phosphates by electrothermal reduction with coke at temperatures of 1400-1600°C in the presence of silica (quartz sand); After cleaning from dust, gaseous phosphorus is sent to condensation units, where liquid technical white phosphorus is collected under a layer of water. The bulk of the phosphorus produced is processed into phosphoric acid and phosphorus fertilizers and technical salts obtained on its basis. Salts of phosphoric acids - phosphates, and to a slightly lesser extent - phosphites and hypophosphites are widely used. White phosphorus is used in the manufacture of incendiary and smoke projectiles; red - in match production.

STRUCTURE OF THE ATOM OF PHOSPHORUS

Phosphorus is located in the III period, in group 5 of the main subgroup “A”, under serial number No. 15. Relative atomic mass A r (P) = 31.

P +15) 2) 8) 5

1S 2 2S 2 2P 6 3S 2 3P 3, phosphorus: p – element, non-metal

Trainer No. 1. "Characteristics of phosphorus by position in the Periodic Table of Elements of D. I. Mendeleev"

The valence possibilities of phosphorus are wider than those of the nitrogen atom, since the phosphorus atom has free d-orbitals. Therefore, pairing of 3S 2 electrons can occur and one of them can move to the 3d orbital. In this case, the third energy level of phosphorus will have five unpaired electrons and phosphorus will be able to exhibit valency V.

In the free state, phosphorus forms several allotscommon modifications: white, red and black phosphorus

"White Phosphorus Glow in the Dark"

Phosphorus is present in living cells in the form of ortho- and pyrophosphoric acids, and is part of nucleotides, nucleic acids, phosphoproteins, phospholipids, coenzymes, and enzymes. Human bones consist of hydroxyapatite 3Ca 3 (PO 4) 3 ·CaF 2. The composition of tooth enamel includes fluorapatite. The liver plays the main role in the transformation of phosphorus compounds in the body of humans and animals. The metabolism of phosphorus compounds is regulated by hormones and vitamin D. The daily human need for phosphorus is 800-1500 mg. With a lack of phosphorus in the body, various bone diseases develop.

TOXICOLOGY OF PHOSPHORUS

· Red phosphorus practically non-toxic. Red phosphorus dust, when inhaled into the lungs, causes chronic pneumonia.

· White phosphorus very toxic, soluble in lipids. The lethal dose of white phosphorus is 50-150 mg. When white phosphorus gets on the skin, it causes severe burns.

Acute phosphorus poisoning is manifested by a burning sensation in the mouth and stomach, headache, weakness, and vomiting. After 2-3 days, jaundice develops. Chronic forms are characterized by calcium metabolism disorders and damage to the cardiovascular and nervous systems. First aid for acute poisoning is gastric lavage, laxatives, cleansing enemas, intravenous glucose solutions. For skin burns, treat the affected areas with solutions of copper sulfate or soda. The maximum permissible concentration for phosphorus vapors in the air is 0.03 mg/m³.

OBTAINING PHOSPHORUS

Phosphorus is obtained from apatites or phosphorites as a result of interaction with coke and silica at a temperature of 1600 ° C:

2Ca 3 (PO 4) 2 + 10C + 6SiO 2 → P 4 + 10CO + 6CaSiO 3.

The resulting white phosphorus vapors are condensed in a receiver under water. Instead of phosphorites, other compounds can be reduced, for example, metaphosphoric acid:

4HPO 3 + 12C → 4P + 2H 2 + 12CO.

CHEMICAL PROPERTIES OF PHOSPHORUS

Oxidizer	Reducing agent
1. With metals - an oxidizing agent, forms phosphides: 2P + 3Ca → Ca 3 P 2 Experiment "Preparation of calcium phosphide" 2P + 3Mg → Mg 3 P 2 . Phosphides decompose acids and water to form phosphine gas Mg 3 P 2 + 3H 2 SO 4 (p-p) = 2PH 3 + 3MgSO 4 Experiment "Hydrolysis of calcium phosphide" Properties of phosphine- PH 3 + 2O 2 = H 3 PO 4. PH 3 + HI = PH 4 I	1. Phosphorus is easily oxidized by oxygen: "Phosphorus Burning" "White Phosphorus Burning Underwater" "Comparison of the ignition temperatures of white and red phosphorus" 4P + 5O 2 → 2P 2 O 5 (with excess oxygen), 4P + 3O 2 → 2P 2 O 3 (with slow oxidation or with a lack of oxygen).
	2. With non-metals - reducing agent: 2P + 3S → P 2 S 3, 2P + 3Cl 2 → 2PCl 3. ! Does not interact with hydrogen .
	3. Strong oxidizing agents convert phosphorus into phosphoric acid: 3P + 5HNO 3 + 2H 2 O → 3H 3 PO 4 + 5NO; 2P + 5H 2 SO 4 → 2H 3 PO 4 + 5SO 2 + 2H 2 O.
	4. The oxidation reaction also occurs when matches are lit; Berthollet salt acts as an oxidizing agent: 6P + 5KClO 3 → 5KCl + 3P 2 O 5

APPLICATION OF PHOSPHORUS

Phosphorus is the most important biogenic element and at the same time finds very wide application in industry.

Perhaps the first property of phosphorus that man has put to his service is flammability. The flammability of phosphorus is very high and depends on allotropic modification.

Most chemically active, toxic and flammable white (“yellow”) phosphorus, therefore it is very often used (in incendiary bombs, etc.).

Red phosphorus- the main modification produced and consumed by industry. It is used in the production of matches; it, together with finely ground glass and glue, is applied to the side surface of the box; when the match head, which contains potassium chlorate and sulfur, is rubbed, ignition occurs. Red phosphorus is also used in the production of explosives, incendiary compositions, and fuels.

Phosphorus (in the form of phosphates) is one of the three most important biogenic elements and is involved in the synthesis of ATP. Most of the phosphoric acid produced is used to produce phosphorus fertilizers - superphosphate, precipitate, etc.

ASSIGNMENT TASKS

No. 1. Red phosphorus is the main modification produced and consumed by industry. It is used in the production of matches; it, together with finely ground glass and glue, is applied to the side surface of the box; when the match head, which contains potassium chlorate and sulfur, is rubbed, ignition occurs.
The reaction occurs:
P + KClO 3 = KCl + P 2 O 5
Arrange the coefficients using an electronic balance, indicate the oxidizing agent and the reducing agent, the processes of oxidation and reduction.

No. 2. Carry out transformations according to the scheme:
P -> Ca 3 P 2 -> PH 3 -> P 2 O 5
For the last reaction PH 3 -> P 2 O 5 draw up an electronic balance, indicate the oxidizing agent and reducing agent.

No. 3. Carry out transformations according to the scheme:
Ca 3 (PO 4 ) 2 -> P -> P 2 O 5