Analysis of potassium according to the plan chemistry. Phosphorus and its compounds. Practical use of phosphorus compounds

Part I

According to the plan considered in the past lesson, give a characteristic of the phosphorus element.
1) This is the VA group member PS, the 3rd small period.
2) Atomic electron formula: + 15P 2e, 6e, 5e.
3) Phosphorus can exhibit oxidative properties with respect to metals and hydrogen, as well as reducing properties with respect to more electronegative elements, for example: O, Cl.
4-6) Allotropy is characteristic of phosphorus. It forms two allotropic modifications: P red and P white. The first one has an atomic crystal lattice, and the second one has a molecular crystal lattice and the P4 formula. Consequently, the cause of the allotropy of phosphorus is the crystal lattice, i.e. different structure.
Phosphorus red and P4 molecules are formed by the covalent non-polar bond. Between P4 molecules - weak intermolecular forces of interaction.
7-8) P\u003e active NM than Si, but< активный, чем S.
Phosphorus< активный восстановитель, чем Si, но > active than S.
9) Higher phosphorus oxide has the formula P2O5 and the name phosphorus oxide V. It is an acid oxide.
It interacts (write down the equations of possible reactions, including in full and abbreviated ionic form for reactions involving electrolytes):

10) The highest phosphorus hydroxide is phosphoric acid, the formula of which.
It is a dibasic, oxygen-containing, water-soluble, non-volatile, stable, but weak acid. Therefore, in the ionic equations of reactions involving phosphoric acid, its formula should be written in molecular form.
The reaction with metals for phosphoric acid is not typical. The remaining properties are typical of acids. It interacts (make up the equations of possible reactions - molecular, complete and abbreviated ionic):

11) Volatile hydrogen compound of phosphorus has the formula PH 3. It is built with a covalent chemical bond. The scheme of her education:

Part II

1. Cross out the "extra".
4) Be

2. Which of the following groups contains only non-metals?
1) VIIA

3. Eliminate the "extra" element in terms of the possibility of the formation of allotropic modifications.
2) nitrogen

4. What type of chemical bond can occur only between atoms of non-metals?
1) covalent polar
4) covalent non-polar

5. A solution of a volatile hydrogen compound of chlorine in water is called hydrochloric or hydrochloric acid.
Give the characteristics of the acid:
by basicity - monobasic
oxygen-free oxygen free
soluble - soluble
on strength - strong.
The compound exhibits all the typical properties of acids (write down the equations of possible reactions in the molecular, complete, and abbreviated ionic forms):

7. Chlorine oxide (VII) exhibits all the typical properties of acidic oxides (confirm by the equations of the corresponding reactions in the molecular, complete and abbreviated ionic forms, where this takes place):

8. Perchloric acid HClO4 - very strong acid, shows all the typical properties of acids. Confirm this conclusion with the equations of the corresponding reactions in the molecular, complete and abbreviated ionic forms.

A) Characterization of phosphorus.
1. Phosphorus is an element of the fifth group and the third period, Z \u003d 15,
Ar (P) \u003d 31.
Accordingly, the phosphorus atom contains 15 protons in the nucleus,
16 neutrons and 15 electrons. The structure of its electron shell
can be reflected using the following scheme:

The phosphorus atoms manifest as oxidative properties (taken
The three electrons that are missing for the completion of the external level are obtained, thus obtaining the oxidation state of -3, for example, in compounds with less electronegative elements — metals, hydrogen, etc.) and reducing properties (3 or 5 electrons are given to more electronegative elements — oxygen , halogens, etc., while acquiring the oxidation states of +3 and +5.)
Phosphorus is a less strong oxidizing agent than nitrogen, but stronger than arsenic, which is associated with an increase in the radii of atoms from nitrogen to arsenic. For the same reason, reducing properties, on the contrary, are enhanced.
2. Phosphorus is a simple substance, a typical non-metal. Phosphorus is characterized by the phenomenon of allotropy. For example, there are allotropic modifications of phosphorus, such as white, red, and black phosphorus, which have different chemical and physical properties.
3. Non-metallic properties of phosphorus are less pronounced than those of nitrogen, but stronger than those of arsenic (neighboring elements in the group).
4. The non-metallic properties of phosphorus are more pronounced than those of
silicon, but weaker than sulfur (adjacent elements in the period).
5. Higher phosphorus oxide has the formula P 2 O 5. This is an acidic oxide.
It exhibits all the typical properties of acidic oxides. For example, when interacting with water, it produces phosphoric acid.
Р 2 O 5 + 3H 2 O \u003d\u003e 2H 3 PO 4.
When interacting with basic oxides and bases, it
gives salt.
P 2 O 5 + 3MgO \u003d Mg 3 (PO 4) 2; Р 2 O 5 + 6KON \u003d 2K 3 РO 4 + 3Н 2 O.
6. Higher phosphorophosphoric acid hydroxide, H 3 PO 4,
the creator of which exhibits all the typical properties of acids: interaction with bases and basic oxides:
H 3 PO 4 + 3NaOH \u003d Na 3 PO 4 + 3H 2 O. 2H 3 PO 4 + 3CaO \u003d Ca, (PO 4) 2 ↓ + 3H 2 O.
7. Phosphorus forms a volatile compound H 3 P - phosphine.

B) Characterization of potassium.
1. Potassium has the serial number 19, Z \u003d 19 and the relative atomic mass Ar (K) \u003d 39. Accordingly, the nuclear charge of its atom is +19 (equal to the number of protons). Consequently, the number of neutrons in the nucleus is 20. Since the atom is electrically neutral, the number of electrons contained in the potassium atom is also equal to 19. The potassium element is in the fourth period of the periodic system, which means that all electrons are located on four energy levels. Thus, the structure of the potassium atom is written as:

Based on the structure of the atom, it is possible to predict the degree of oxidation
potassium in its compounds. Since in chemical reactions, the potassium atom gives one external electron, showing reducing properties, therefore, it acquires an oxidation state of +1.
The reducing properties of potassium are more pronounced than that of
but it is weaker than that of rubidium, which is associated with an increase in the radii from Na to Rb.
2. Potassium is a simple substance, it is characterized by metallic
the crystal lattice and the metallic chemical bond, and hence all the properties typical of metals.
3. Metallic properties of potassium are more pronounced than those of
triya, but weaker than rubidium, because a potassium atom gives up an electron more easily than a sodium atom, but is harder than a rubidium atom.
4. Metallic properties of potassium are more pronounced than those of calcium, since one electron of a potassium atom is easier to tear off than two electrons
calcium atom.
5. Potassium oxide K 2 O is the basic oxide and exhibits all the typical properties of the basic oxides. Interaction with acids and acid oxides.
K 2 O + 2HCl \u003d 2KSl + H 2 O; K 2 O + SO 3 \u003d K 2 SO 4.
6. As potassium hydroxide, there corresponds the base (alkali) KOH, which exhibits all the characteristic properties of bases: interaction with acids and acid oxides.
KOH + HNO 3 \u003d KNO 3 + H 2 O; 2KOH + N 2 O 5 \u003d 2KNO 3 + H 2 O.
7. Potassium does not form a volatile hydrogen compound, but forms potassium hydride KH.

Among biogenic elements, phosphorus should be highlighted. Indeed, without it, the existence of such vital compounds as, for example, ATP or phospholipids, as well as many others is impossible. Moreover, the inorganic structure of this element is very rich in various molecules. Phosphorus and its compounds are widely used in industry, are important participants in biological processes, are used in various fields of human activity. Therefore, consider what constitutes this element, what is its simple substance and the most important compounds.

Phosphorus: general characteristic of the element

The position in the periodic system can be described in several points.

The fifth group, the main subgroup.
The third small period.
The sequence number is 15.
The atomic mass is 30.974.
The electron configuration of the atom 1s 2 2s 2 2p 6 3s 2 3p 3.
Possible oxidation rates from -3 to +5.
Chemical symbol - P, pronunciation in the formulas "pe". The name of the element is phosphorus. The Latin name is Phosphorus.

The history of the discovery of this atom has its roots in the distant XII century. Even in the records of the alchemists there was information that spoke of the receipt of an unknown "luminous" substance. However, the official date of synthesis and discovery of phosphorus was 1669. A bankrupt merchant Brand, in search of a philosopher's stone, accidentally synthesized a substance capable of emitting a glow and burning with a bright blinding flame. He did this by repeatedly burning human urine.

After him, independently from each other in approximately the same ways, this element was obtained:

I. Kunkel;
R. Boyle;
A. Marggraf;
K. Scheele;
A. Lavoisier.

Today, one of the most popular methods for the synthesis of this substance is the reduction of 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 for both living creatures and for many syntheses in the chemical industry. Therefore, we should consider what constitutes this element as a simple substance and where it is contained in nature.

Simple substance phosphorus

It is difficult to name any particular compound when it comes to phosphorus. This is due to the large number of allotropic modifications that this element has. There are four main varieties of simple phosphorus substances.

White. This is a compound whose formula is P 4. It is a white volatile substance with a strong unpleasant smell of garlic. Ignite spontaneously in air at normal temperatures. Burns with a glowing pale green light. Very toxic and life threatening. Reactivity is extremely high, so they get it and store it under a layer of purified water. This is possible due to poor solubility in polar solvents. The best way for this white phosphorus is carbon disulfide and organic matter. When heated, it can transfer to the following allotropic form - red phosphorus. During condensation and cooling, vapor is able to form seams. It feels greasy, soft, easily cut with a knife, white (slightly yellowish). Melting point 44 0 C. Due to its chemical activity it is used in syntheses. But because of its toxicity, it does not have wide industrial application.
Yellow. This is a poorly purified form of white phosphorus. It is even more poisonous, it also smells like garlic. It burns and burns with a bright glowing green flame. These yellow or brown crystals do not dissolve in water at all, with full oxidation they emit puffs of white smoke with the composition P 4 O 10.
Red phosphorus and its compounds are the most common and most commonly used in the industry modification of this substance. Pasty red mass, which at elevated pressure can turn into the form of purple crystals, is chemically inactive. It is a polymer that can dissolve only in certain metals and is no longer in anything. At a temperature of 250 0 C sublimates, turning into a white modification. Not as toxic as previous forms. However, with prolonged exposure to the body is toxic. It is used in the application of igniting coating on matchboxes. This is explained by the fact that it cannot ignite spontaneously, but explodes (ignites) during denotation and friction.
The black. According to external data is very similar to graphite, is also greasy to the touch. It is a semiconductor electric current. Dark crystals, shiny, which are not able to dissolve in any solvents at all. In order for it to catch fire, we need very high temperatures and preliminary incandescence.

Also interesting not so long ago, the open form of phosphorus - metal. It is a conductor and has a cubic crystal lattice.

Chemical properties

The chemical properties of phosphorus depend on the form in which it is found. 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 nonvolatile compounds of various kinds;
strong oxidizing agents, going into;
with concentrated caustic alkalis by type of disproportionation;
with water at very high temperature;
with oxygen to form different oxides.

The chemical properties of phosphorus are similar to those of nitrogen. after all, he belongs to the group of pnictogens. However, the activity is several orders higher due to the variety of allotropic modifications.

Being in nature

As a nutrient, phosphorus is very common. Its percentage in the earth's crust is 0.09%. This is quite a large indicator. Where does this atom occur in nature? There are several main places:

the green part of the plants, their seeds and fruits;
animal tissues (muscles, bones, tooth enamel, many important organic compounds);
earth's crust;
the soil;
rocks and minerals;
sea \u200b\u200bwater.

At the same time, one can speak only about connected 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, the richest in phosphorus are:

english;
fluorapaptit;
svanbergite;
phosphorite and others.

The biological value of this element can not be overemphasized. After all, it is part of such compounds as:

squirrels;
phospholipids;
phosphoproteins;
enzymes.

That is, all those that are vital and from which the whole organism is built as a whole. The daily rate for an ordinary adult about 2 grams.

Phosphorus and its compounds

As very active, this element forms many different substances. After all, it forms and phosphides, and he acts as a reducing agent. Because of 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: P 2 O 5, PCL 3, P 2 S 3, PH 3, and others.
Complex substances: salts of all types (medium, acidic, basic, double, complex), acids. Example: H 3 PO 4, Na 3 PO 4, H 4 P 2 O 6, Ca (H 2 PO 4) 2, (NH 4) 2 HPO 4 and others.
Oxygen-containing organic compounds: proteins, phospholipids, ATP, DNA, RNA and others.

Most of the indicated types of substances have important industrial and biological significance. The use of phosphorus and its compounds is possible both for medical purposes and for the manufacture of completely everyday household items.

Compounds with metals

Binary phosphorus compounds with metals and less electronegative non-metals are called phosphides. These are salt-like substances, which are extremely unstable when exposed to different agents. Rapid decomposition (hydrolysis) causes even ordinary water.

In addition, under the action of non-concentrated acids, the decomposition of the substance into the corresponding products also occurs. For example, if we talk about the hydrolysis of calcium phosphide, the products will be metal hydroxide and phosphine:

Ca 3 P 2 + 6H 2 O \u003d 3Ca (OH) 2 + 2PH 3

And subjecting phosphide to decomposition under the action of a mineral acid, we get the corresponding salt and phosphine:

Ca 3 P 2 + 6HCL \u003d 3CaCL 2 + 2PH 3

In general, the value of the compounds in question is precisely in the fact that the result is a hydrogen compound of phosphorus, the properties of which are discussed below.

Phosphorus based volatiles

There are two main ones:

white phosphorus;
phosphine.

We already mentioned the first one and the characteristics were given. They said it was white thick smoke, very poisonous, smelling unpleasant 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 phosphorus hydrogen compound is PH 3, the name is phosphine.

The properties of this substance can be described as follows.

Flying colorless gas.
Very poisonous.
It has the smell of rotten fish.
Does not interact with water and dissolves very poorly in it. Well soluble in organics.
Under normal conditions it is very chemically active.
Self-igniting in air.
Formed by the decomposition of metal phosphides.

Another name is phosphane. Associated with it are stories from antiquity itself. The whole thing in which sometimes people saw and see now in cemeteries, marshes. Ball-shaped 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 reason for this phenomenon, according to the modern views of some scientists, is the spontaneous combustion of phosphine, which is formed naturally by the decomposition of organic residues, both plant and animal. The gas comes out and, in contact with the oxygen of the air, lights up. Flame color and size may vary. Most often, it is a greenish bright lights.

It is obvious that all volatile phosphorus compounds are toxic substances that are easily detected by a sharp unpleasant odor. This symptom helps to avoid poisoning and unpleasant consequences.

Compounds with non-metals

If phosphorus behaves as a reducing agent, then one should speak about binary compounds with non-metals. Most often, they are more electronegative. So, you can select several types of substances of this kind:

a compound of phosphorus and sulfur - phosphorus sulfide P 2 S 3;
phosphorus chloride III, V;
oxides and anhydride;
bromide and iodide, and others.

The chemistry of phosphorus and its compounds is diverse, so it is difficult to identify the most important ones. If we talk specifically about the substances that are formed from their phosphorus and non-metals, then oxides and chlorides of different composition are most important. They are used in chemical syntheses as water-removing agents, as catalysts, and so on.

So, one of the most powerful drying means is the highest - P 2 O 5. It so strongly attracts water that when in direct contact with it a violent reaction occurs with strong noise accompaniment. In itself, the substance is a white snow-like mass, on an aggregate state closer to the amorphous.

It is known that organic chemistry is far superior to inorganic chemistry. This is explained by the phenomenon of isomerism and the ability of carbon atoms to form different structures of a chain of atoms, becoming isolated with each other. Naturally, there is a certain order, that is, a classification that governs all organic chemistry. Classes of compounds 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;
squirrels;
nucleic acids, since the phosphoric acid residue is part of the nucleotide;
phospholipids and phosphoproteins;
enzymes and catalysts.

The type of ion in which phosphorus is involved in the formation of a molecule of these compounds is as follows: PO 4 3-, that is, it is an acidic residue of phosphoric acid. It is a part of some proteins in the form of a free atom or a simple ion.

For the normal life of each 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.

The 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 an absorber of gases, as well as in the manufacture of incandescent lamps.
To protect metals from corrosion.
In agriculture as a fertilizer soil.
As a means for softening water.
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 capacity of the internal environment of the cell and biological fluids. It is the basis for the synthesis of DNA, RNA, phospholipids.