Among the biogenic elements, a special place should be given to phosphorus. Indeed, without it, the existence of such vital compounds as, for example, ATP or phospholipids, as well as many other organic substances, is impossible. At the same time, the inorganic matter of this element is very rich in various molecules. Phosphorus and its compounds are widely used in industry, are important participants in biological processes, and are used in various branches of human activity. Therefore, consider what this element is, what its simple substance and the most important compounds are.
Phosphorus: general characteristics of the element
The position in the periodic table can be described in several points.
- Fifth group, main subgroup.
- Third small period.
- Ordinal number - 15.
- Atomic mass is 30, 974.
- Electronic configuration of the atom 1s22s22p63s 23p3.
- Possible oxidation states from-3 to +5.
- Chemical symbol - P, pronunciation in formulas "pe". The name of the element is phosphorus. Latin name Phosphorus.
The history of the discovery of this atom goes back to the distant XII century. Even in the records of alchemists there was information indicating the receipt of an unknown "luminous" substance. However, the official date for the synthesis and discovery of phosphorus was 1669. The bankrupt merchant Brand, in search of the philosopher's stone, accidentally synthesized a substance capable of emitting a glow and burning with a bright blinding flame. He did this by repeatedly calcining human urine.
After it, independently of each other, this element was received in approximately the same ways:
- I. Kunkel;
- R. Boyle;
- A. Margrave;
- K. Scheele;
- A. Lavoisier.
Today, one of the most popular methods for the synthesis of this substance is the reduction from the corresponding phosphorus-containing minerals at high temperatures under the influence of carbon monoxide and silica. The process is carried out in special furnaces. Phosphorus and its compounds are very important substances both for living beings and for many syntheses in the chemical industry. Therefore, one should consider what this element is as a simple substance and where it is found in nature.
Simple substance phosphorus
It's hard to name a specific compound when it comes to phosphorus. This is due to the numerousallotropic modifications that this element has. There are four main varieties of the simple substance phosphorus.
- White. This is a compound whose formula is Р4. It is a white volatile substance with a sharp unpleasant odor of garlic. It ignites spontaneously in air at normal temperatures. Burns with a luminous pale green light. Very poisonous and life-threatening. The chemical activity is extremely high, so it is obtained and stored under a layer of purified water. This is possible due to poor solubility in polar solvents. Carbon disulfide and organic substances are best suited for this white phosphorus. When heated, it is capable of transforming into the next allotropic form - red phosphorus. When condensing and cooling vapors, it is able to form layers. Oily to the touch, soft, easily cut with a knife, white (slightly yellowish). Melting point 440C. Due to its chemical activity it is used in syntheses. But due to its toxicity, it does not have a wide industrial application.
- Yellow. It is a poorly purified form of white phosphorus. It is even more poisonous, it also smells unpleasantly of garlic. Ignites and burns with a bright luminous green flame. These yellow or brown crystals do not dissolve in water at all; when fully oxidized, they emit puffs of white smoke with the composition P4O10.
- Red phosphorus and its compounds are the most common and most commonly used modification of this substance in industry. Pasty red mass, which under increased pressure canto pass into the form of violet crystals, is chemically inactive. It is a polymer that can only dissolve in certain metals and nothing else. At a temperature of 2500С, it sublimates, turning into a white modification. Not as toxic as previous forms. However, long-term exposure to the body is toxic. It is used in applying an incendiary coating to matchboxes. This is explained by the fact that it cannot ignite spontaneously, but it explodes (ignites) during denotation and friction.
- Black. According to external data, it is very similar to graphite, it is also greasy to the touch. It is an electrical semiconductor. Dark crystals, shiny, which are not able to dissolve in any solvents at all. In order for it to catch fire, very high temperatures and preliminary heating are needed.
Also interesting is the recently discovered form of phosphorus - metallic. It is a conductor and has a cubic crystal lattice.
Chemical properties
The chemical properties of phosphorus depend on what form it is in. As mentioned above, the most active yellow and white modification. In general, phosphorus is able to interact with:
- metals, forming phosphides and acting as an oxidizing agent;
- non-metals, acting as a reducing agent and forming volatile and non-volatile compounds of various kinds;
- strong oxidizing agents, turning into phosphoric acid;
- with concentrated caustic alkalis by typedisproportionation;
- with water at very high temperature;
- with oxygen to form various oxides.
The chemical properties of phosphorus are similar to those of nitrogen. After all, he is part of the pnictogen group. However, the activity is several orders of magnitude higher due to the variety of allotropic modifications.
Being in nature
As a nutrient, phosphorus is very abundant. Its percentage in the earth's crust is 0.09%. This is a fairly large indicator. Where is this atom found in nature? There are several main places to name:
- green part of plants, their seeds and fruits;
- animal tissues (muscles, bones, tooth enamel, many important organic compounds);
- crust;
- soil;
- rocks and minerals;
- sea water.
In this case, we can only talk about related forms, but not about a simple substance. After all, he is extremely active, and this does not allow him to be free. Among the minerals richest in phosphorus are:
- English;
- fluorapaptite;
- svanbergite;
- phosphorite and others.
The biological significance of this element cannot be overestimated. After all, it is part of compounds such as:
- proteins;
- phospholipids;
- DNA;
- RNA;
- phosphoproteins;
- enzymes.
That is, all those that are vital and from which the whole organism is built. The daily allowance for an average adult is about 2 grams.
Phosphorus and its compounds
Being very active, this element forms many different substances. After all, it also forms phosphides, and itself acts as a reducing agent. Due to this, it is difficult to name an element that would be inert when reacting with it. Therefore, the formulas of phosphorus compounds are extremely diverse. There are several classes of substances in the formation of which he is an active participant.
- Binary compounds - oxides, phosphides, volatile hydrogen compound, sulfide, nitride and others. For example: P2O5, PCL3, P2 S3, PH3 and others.
- Complex substances: s alts of all types (medium, acidic, basic, double, complex), acids. Example: N3PO4, Na3PO4, H4P2O6, Ca(H2 PO4)2, (NH4)2 HPO4 and others.
- Oxygen-containing organic compounds: proteins, phospholipids, ATP, DNA, RNA and others.
Most of the designated types of substances are of great industrial and biological importance. The use of phosphorus and its compounds is possible both for medical purposes and for the manufacture of quite ordinary household items.
Compounds with metals
Binary compounds of phosphorus with metals and less electronegative non-metals are called phosphides. These are s alt-like substances that are extremely unstable when exposed to various agents. Rapid decomposition (hydrolysis) causes evenplain water.
In addition, under the action of non-concentrated acids, the substance also breaks down into the corresponding products. For example, if we talk about the hydrolysis of calcium phosphide, then the products will be metal hydroxide and phosphine:
Ca3P2 + 6H2O=3Ca(OH) 2 + 2PH3↑
And by subjecting the phosphide to decomposition under the action of a mineral acid, we get the corresponding s alt and phosphine:
Ca3P2 + 6HCL=3CaCL2 + 2PH 3↑
In general, the value of the compounds under consideration lies precisely in the fact that as a result a hydrogen compound of phosphorus is formed, the properties of which will be considered below.
Volatile substances based on phosphorus
There are two main ones:
- white phosphorus;
- phosphine.
We already mentioned the first one above and gave the characteristics. They said it was thick white smoke, highly poisonous, foul-smelling, and self-igniting under normal conditions.
But what is phosphine? This is the most common and well-known volatile substance, which includes the element in question. It is binary, and the second participant is hydrogen. The formula of the hydrogen compound of phosphorus is pH3, the name is phosphine.
The properties of this substance can be described as follows.
- Volatile colorless gas.
- Very poisonous.
- It smells like rotten fish.
- Does not interact with water and dissolves very poorly in it. Well soluble inorganics.
- Under normal conditions, very reactive.
- Self-ignites in air.
- Produced from the decomposition of metal phosphides.
Another name is Phosphane. Stories from ancient times are associated with it. It's all about the "wandering lights" that people sometimes saw and see now in cemeteries and swamps. Spherical or candle-like lights that appear here and there, giving the impression of movement, were considered a bad omen and superstitious people were very afraid of them. The cause of this phenomenon, according to the modern views of some scientists, can be considered the spontaneous combustion of phosphine, which is formed naturally during the decomposition of organic residues, both plant and animal. The gas comes out and, in contact with oxygen in the air, ignites. Flame color and size may vary. Most often, these are greenish bright lights.
Obviously, all volatile phosphorus compounds are poisonous substances that are easily detected by a sharp unpleasant odor. This sign helps to avoid poisoning and unpleasant consequences.
Compounds with nonmetals
If phosphorus behaves as a reducing agent, then we should talk about binary compounds with non-metals. Most often, they are more electronegative. So, we can distinguish several types of substances of this kind:
- compound of phosphorus and sulfur - phosphorus sulfide P2S3;
- phosphorus chloride III, V;
- oxides and anhydride;
- bromide and iodide andothers.
The chemistry of phosphorus and its compounds is diverse, so it is difficult to identify the most important of them. If we talk specifically about the substances that are formed from phosphorus and non-metals, then oxides and chlorides of various compositions are of the greatest importance. They are used in chemical syntheses as dewatering agents, as catalysts, and so on.
So, one of the most powerful drying agents is the highest phosphorus oxide - P2O5. It attracts water so strongly that in direct contact with it, a violent reaction occurs with strong noise accompaniment. By itself, the substance is a white snow-like mass, closer to amorphous in its state of aggregation.
Oxygenated organic compounds with phosphorus
It is known that organic chemistry far exceeds inorganic chemistry in terms of the number of compounds. This is explained by the phenomenon of isomerism and the ability of carbon atoms to form chains of atoms of various structures, closing with each other. Naturally, there is a certain order, that is, a classification, to which all organic chemistry is subject. The connection classes are different, however, we are interested in one specific, directly related to the element in question. These are oxygen-containing compounds with phosphorus. These include:
- coenzymes - NADP, ATP, FMN, pyridoxal phosphate and others;
- proteins;
- nucleic acids, since the phosphoric acid residue is part of the nucleotide;
- phospholipids and phosphoproteins;
- enzymes and catalysts.
Type of ion in whichphosphorus is involved in the formation of a molecule of these compounds, the next one is PO43-, that is, it is an acid residue of phosphoric acid. It is included in some proteins in the form of a free atom or a simple ion.
For the normal functioning of every living organism, this element and the organic compounds formed by it are extremely important and necessary. Indeed, without protein molecules, it is impossible to build a single structural part of the body. And DNA and RNA are the main carriers and transmitters of hereditary information. In general, all connections must be present without fail.
Use of phosphorus in industry
The use of phosphorus and its compounds in industry can be characterized in several points.
- Used in the manufacture of matches, explosive compounds, incendiary bombs, some fuels, lubricants.
- As a gas absorber and in the manufacture of incandescent lamps.
- To protect metals from corrosion.
- In agriculture as soil fertilizer.
- As a water softener.
- In chemical syntheses in the production of various substances.
The role in living organisms is reduced to participation in the formation of tooth enamel and bones. Participation in the reactions of ana- and catabolism, as well as maintaining the buffering of the internal environment of the cell and biological fluids. It is the basis in the synthesis of DNA, RNA, phospholipids.
