Slide 7

At the beginning of the 20th century, a scandalous story occurred at a military equipment warehouse in St. Petersburg: during an audit, to the horror of the quartermaster, it turned out that tin buttons for soldiers’ uniforms had disappeared, and the boxes in which they were stored were filled to the top with gray powder. And although it was bitterly cold in the warehouse, the unfortunate quartermaster felt hot. Of course: he will, of course, be suspected of theft, and this does not promise anything other than hard labor. What saved the poor fellow was the conclusion of the chemical laboratory, where the auditors sent the contents of the boxes: “The substance you sent for analysis is undoubtedly tin. Obviously, in this case, a phenomenon known in chemistry as the “tin plague” took place. ?

Slide 8

"Tin Plague"

White tin is stable at t0 >130С Gray tin is stable at t0

Slide 9

Allotropy is the ability of atoms of one chemical element to form several simple substances. Allotropic modifications are simple substances formed by atoms of the same chemical element.

Slide 10

Allotropic modifications of oxygen

O2 is oxygen, a colorless gas; has no smell; poorly soluble in water; boiling point -182.9 C. O3 – ozone (“smelling”) gas of pale violet color; has a pungent odor; dissolves 10 times better than oxygen; boiling point -111.9 C; most bactericidal.

Slide 11

Allotropic modifications of carbon

Graphite Diamond Soft Has a gray color Low metallic luster Electrically conductive Leaves a mark on paper. Hard Colorless Cuts glass Refracts light Dielectric

Slide 12

Fullerene Carbin Graphene Harder and stronger than diamond, but stretches to a quarter of its length, like rubber. Graphene does not allow gases and liquids to pass through, and conducts heat and electricity better than copper. Fine-crystalline black powder (density 1.9-2 g/cm³), semiconductor.

Slide 13

Rhombic sulfur is a type of octahedron with cut corners. Light yellow powder. Monoclinic sulfur - in the form of needle-shaped crystals yellow color. Plastic sulfur is a rubber-like mass of dark yellow color. Can be obtained in the form of threads.

Slide 14

Allotropic modifications of phosphorus

P (red phosphorus) (white phosphorus) P4 Odorless, does not glow in the dark, non-toxic! It has a garlicky smell, glows in the dark, and is poisonous!

Slide 15

С4Н8

Here is a painting by an unknown artist. The one who offers the most isomers will be able to purchase it. Starting price – 2 isomers.

Slide 16

CH2 = CH – CH2 – CH3 CH2 = C – CH3 Butene-1CH3 2-methylpropene-1 (methylpropene) Butene-2 ​​CH3 CH = CH–CH3 C = C C = C CH3 CH3 CH3 CH3 H H H H Cis – butene - 2 Trans - butene - 2 H2C CH2 H2C CH2 Cyclobutane H2C CH CH3 CH2 methylcyclopropane

Reasons for diversity chemical substances

Currently, the reasons for the diversity of chemical substances are usually explained by two phenomena - isomerism and allotropy.

Substances that have the same composition, but different chemical or spatial structures, and therefore different properties, are called isomers.

Main types isomerism :

Structural isomerism, in which substances differ in the order of bonding of atoms in molecules:isomerism carbon skeleton

isomerism positions of multiple bonds:

deputies

isomerism positions of functional groups

ALLOTROPY, the existence of chemical elements in two or more molecular or crystalline forms. For example, allotropes are ordinary oxygen O2 and ozone O3; in this case, allotropy is due to the formation of molecules with different numbers of atoms. Most often, allotropy is associated with the formation of crystals of various modifications. Carbon exists in two distinct crystalline allotropes: diamond and graphite. Previously it was believed that the so-called. amorphous forms of carbon, charcoal and soot are also its allotropic modifications, but it turned out that they have the same crystalline structure as graphite. Sulfur occurs in two crystalline modifications: orthorhombic (a-S) and monoclinic (b-S); at least three of its non-crystalline forms are known: l-S, m-S and violet. For phosphorus, white and red modifications have been well studied, black phosphorus has also been described; at temperatures below -77° C there is another type of white phosphorus. Allotropic modifications of As, Sn, Sb, Se were discovered, and when high temperatures- iron and many other elements.

Enantiotropic and monotropic forms. Crystalline modifications of a chemical element can transform into one another in different ways, which can be illustrated by the examples of sulfur and phosphorus. At ordinary temperatures, the orthorhombic modification of sulfur is stable, which, when heated to 95.6 ° C and a pressure of 1 atm, transforms into a monoclinic form. The latter, when cooled below 95.6 ° C, again transforms into a rhombic form. Thus, the transition from one form of sulfur to another occurs at the same temperature, and the forms themselves are called enantiotropic. A different picture is observed for phosphorus. Its white form can turn red at almost any temperature. At temperatures below 200° C, the process proceeds very slowly, but it can be accelerated with the help of a catalyst, such as iodine. The reverse transition of red phosphorus to white is impossible without the formation of an intermediate gas phase. The red form is stable over the entire temperature range where it is in the solid state, while the white form is unstable at any temperature (metastable). A transition from an unstable form to a stable one is, in principle, possible at any temperature, but the reverse is not, i.e. there is no specific transition point. Here we are dealing with monotropic modifications of the element. Two known modifications of tin are enantiotropic. Carbon modifications - graphite and diamond - are monotropic, and the graphite form is stable. The red and white forms of phosphorus are monotropic, and its two white modifications are enantiotropic, the transition temperature is -77 ° C at a pressure of 1 atm.

The lesson will examine types of crystal lattices, types of aggregate states of matter, and solids with a crystalline structure. The concept of polymorphism and allotropy is introduced.

I. Repetition

Repeat from the 8th grade course:

II. The variety of substances in the surrounding world

Currently, more than 100 chemical elements are known. They form more than 400 simple substances and several million of a wide variety of complex chemical compounds. What are the reasons for this diversity?

1. Isotopy of elements and their compounds

Isotopes - a variety of atoms of the same chemical element, differing from each other only in their mass.

For example, the hydrogen atom has three isotopes: 1 1 H - protium, 1 2 H (D) - deuterium and 1 3 H (T) - tritium. They and oxygen form a complex substance - water of various compositions: ordinary natural water - H 2 O, heavy water - D 2 O (contained in natural water in the ratio H: D = 6900: 1).

Isobars , atoms of different chemical elements with the same mass number A.

Isobar nuclei (in chemistry) contain an equal number of nucleons, but different numbers of protons Z and neutrons N.

For example, the atoms 4 10 Be, 5 10 B, 6 10 C represent three Isobars (in chemistry) with A = 10.

2. Allotropy

Allotropy - the phenomenon of the existence of a chemical element in the form of several simple substances (allotropic modifications or allotropic modifications).

For example, the oxygen atom occurs in the form of oxygen and ozone.

Audio Definition: “Allotropy”

Allotropy is explained by the different composition of a substance or the difference in their crystal lattice. Acid and ozone are al-lo-tropic mo-di-fi-ka-tions of hi-mi-che-sko-go element-men-ta sour-lo-ro-da. Coal-le-rod ob-ra-zu-et graph-fit, diamond, full-le-ren, car-bin. The distribution of atoms in their crystal lattice is different, and that is why they manifest their different -stva. Phosphorus has all-tropic substances - red, white and black phosphorus. Al-lo-tro-piya ha-rak-ter-na and for metals. For example, iron can exist in the form of α, β, δ, γ.

Te-ku-honor of amorphous substances

One of the properties by which amorphous bodies are distinguished from liquid ones is their fluidity. If you put a piece of resin on a heated surface, then it will gradually spread over this surface.

Viscosity- this is the ability to resist the movement of some parts of the body from others for liquids and gases : the higher it is, the more difficult it is to change the shape of the body. Window glass is a typical amorphous substance. Theo-re-ti-che-ski, they should gradually flow down. But the viscosity of the glass is high, and its deformation can be ignored. The viscosity of glass is approximately 1000 times higher than the viscosity of resin. Over the course of a year, the deformation of glass becomes 0.001%. Over 1000 years, the deformation of glass becomes 1%.

Dependence of the state of aggregation on long- and short-range order of arrangement

Depending on the pressure and temperature, all substances can exist in different ag-res -gat-nyh with-sto-ya-ni-yah: solid, liquid, gas-based or in the form of plasma. At low temperatures and high pressure, all substances exist in a solid ag-re-gat. hundred-i-nii. Solid and liquid substances are called kon-den-si-ro-van-nym.

In solid bodies, the parts are distributed compactly, in a certain row. Depending on the degree of concentration of particles in solids, 2 phase conditions are determined sto-i-niya: crystal-li-che-che-skoe and amorphous. If the parts are distributed in such a way that there is some kind of abutment between the neighboring parts, adequacy in race, namely: exact distance and angles between them, such a phenomenon is called close-in-a-row in the same dis-position. Rice. A.

A b

Rice. 1. Are there near and far in a row in the distribution of particles?

If the parts are distributed in such a way that the emphasis is on the blue and between close-to-si-si-mi, and at the greatest distances, this is what they call far away in a row. Rice. b.

Examples of amorphous substances

Amorphous body(from Greek A - not, morphe - form) - formless substances. In them there is only a nearby row and no further row.

Examples of amorphous bodies are shown in Fig. 2.

Rice. 2. Amorphous bodies

These are wax, glass, plasticine, resin, chocolate.

Properties of amorphous substances

• They only have a close order (as in liquids).
• Solid ag-re-gat-noe under normal conditions.
• There is no clear melting temperature. Swimming in the inter-va-le temp-pe-ra-tour.

Crystalline substances

IN cry-has-become-che-skom the body exists both near and far in a row. If you mentally connect the points that represent the lines, you get a spatial framework, which -wha-it-has-become-a-grill. Points in which particles are located - ions, atoms or molecules - are called knots of crystals -che-skoy lattice (Fig. 3). The parts are not rigidly fixed at the nodes; they can scramble a little without running away from these points. Depending on what parts are in the nodes of the crystal-steel lattice, you its types (Table 1).

Rice. 3. Cry-has-be-come-re-shet-ka

Dependence of properties on the type of crystal lattice

Physical properties of substances with different types of crystals

Table 1. Physical properties of substances

There are several sub-types of cry-ste-che-re-she-currents, different races -eat atoms in space.

In substances with an atomic, ionic, metal-li-che-cry-steel lattice, there are no mo-le-cools - this silent substances.Molecular substances- with a mo-le-ku-lyar-cry-ste-li-grid.

Polymorphism

Polymorphism - this is a phenomenon in which complex substances of the same composition have different crystals -shet-ki.

For example, pyrite and mar-ka-site. Their shape is FeS2. But they look different, and have different physics -stva-mi. Ana-logic-but, different-personal-mi-fi-zi-che-ski-mi properties-mi-la-da-yut mi-ne-ra-ly so-sta-va CaCO3: ara-go-nit, marble, Iceland spar, chalk.

2Preparation of alcohols from saturated and unsaturated hydrocarbons. Industrial synthesis of methanol.

3. Experiment. Carrying out transformations: salt - insoluble base - metal oxide.

When heated, sulfuric acid reacts with copper(II) oxide. Cu 2+ ions pass into the solution and give it a blue color.

CuO + H 2 SO 4 = CuSO 4 (copper sulfate salt) + H 2 O,

CuO + 2H + = Cu 2+ + H 2 O.

An alkali solution is added to the filtrate, and a blue precipitate appears:

CuSO 4 + 2NaOH = Cu(OH) 2 (insoluble copper oxide) + Na 2 SO 4,

Cu 2+ + 2OH – = Cu(OH) 2.

When a blue precipitate of copper (II) hydroxide is heated, a black substance is formed - this is copper (II) oxide and water:
Cu(OH)2 = CuO + H2O

1. Higher oxygen-containing acids and chemical elements of the third period, their composition and Comparative characteristics properties.

Phosphorus forms a number of oxygen-containing acids (oxoacids). Some of them are monomeric. for example, phosphinic, phosphorous and phosphoric(V) (orthophosphoric) acids. Phosphorus acids can be monobasic (single-protic) or polybasic (multiprotic). In addition, phosphorus also forms polymeric oxoacids. Such acids can have an acyclic or cyclic structure. For example, diphosphoric(V) (pyrophosphoric) acid is a dimeric oxoacid of phosphorus.

The most important of all these acids is phosphoric (V) acid (its other name is orthophosphoric acid). Under normal conditions, it is a white crystalline substance that spreads when it absorbs moisture from the air. Its 85% aqueous solution is called “phosphoric acid syrup.” Phosphorus(V) acid is a weak tribasic acid:

Chlorine forms several oxygen-containing acids. The higher the oxidation state of chlorine in these acids, the higher their thermal stability and acid strength:

HOCl< НСlO2 < НСlO3 < НClO4

HClO3 and HClO4 are strong acids, and HClO4 is one of the strongest among all known acids. The remaining two acids only partially dissociate in water and exist in an aqueous solution mainly in molecular form. Among oxygen-containing chlorine acids, only HClO4 can be isolated in free form. Other acids exist only in solution.

The oxidizing ability of oxygen-containing acids of chlorine decreases with increasing oxidation state:

HOCl and HClO2 are especially good oxidizing agents. For example, an acidic solution of HOCl:

1) oxidizes iron (II) ions to iron (III) ions:

2) decomposes in sunlight to form oxygen:

3) when heated to approximately 75 °C, it disproportionates into chloride ions and chlorate (V) ions:

The remaining higher acid-containing acids of the elements of the third period (H3AlO3, H2SiO3) are weaker than phosphoric acid. Sulfuric acid (H2SO4) is less strong than perchloric (VII) acid, but stronger than phosphoric acid. In general, as the oxidation state of an acid-forming element increases, the strength of the acid itself increases:

H3AlO3< H2SiO3 < H3PO4 < H2SO4 < НСlO4

2. general characteristics high-molecular compounds: composition, structure, reactions underlying their production (for example, polyethylene or synthetic rubber).

3. 3 a d a h a. Calculation of the mass of the starting substance if the practical yield of the product is known and its mass fraction (in percent) of the theoretically possible yield is indicated.

Task. Determine the mass of magnesium carbonate reacted with hydrochloric acid if 8.96 liters of carbon monoxide (IV) are obtained, which is 80% of the theoretically possible yield.

Ticket number 25.

General methods of obtaining metals. The practical significance of electrolysis using the example of salts of oxygen-free acids.

Metals are found in nature mainly in the form of compounds. Only metals with low chemical activity (noble metals) are found in nature in a free state (platinum metals, gold, copper, silver, mercury). Of the structural metals, only iron, aluminum, and magnesium are found in sufficient quantities in nature in the form of compounds. They form thick deposits of relatively rich ores. This makes them easier to harvest on a large scale.

Since the metals in the compounds are in an oxidized state (have a positive oxidation state), obtaining them in a free state comes down to a reduction process:

This process can be carried out chemically or electrochemically.

In chemical reduction, the reducing agent most often used is coal or carbon (II) monoxide, as well as hydrogen, active metals, silicon. With the help of carbon monoxide (II), iron is produced (in the blast furnace process), many non-ferrous metals (tin, lead, zinc, etc.):

Hydrogen reduction is used, for example, to produce tungsten from tungsten(VI) oxide:

The use of hydrogen as a reducing agent ensures the highest purity of the resulting metal. Hydrogen is used to produce very pure iron, copper, nickel and other metals.

A method for producing metals in which metals are used as a reducing agent is called metallothermic. In this method, active metals are used as a reducing agent. Examples of metallothermic reactions:

aluminothermy:

Magniethermy:

Metallothermic experiments in the production of metals were first carried out by the Russian scientist N. N. Beketov in the 19th century.

Metals are most often obtained by the reduction of their oxides, which in turn are isolated from the corresponding natural ore. If the source ore is sulfide minerals, then the latter are subjected to oxidative roasting, for example:

Electrochemical production of metals is carried out by electrolysis of melts of the corresponding compounds. In this way, the most active metals, alkali and alkaline earth metals, aluminum, and magnesium are obtained.

Electrochemical reduction is also used for refining(purification) of “raw” metals (copper, nickel, zinc, etc.) obtained by other methods. During electrolytic refining, a “rough” (with impurities) metal is used as an anode, and a solution of compounds of this metal is used as an electrolyte.

Methods for producing metals carried out at high temperatures are called pyrometallurgical(in Greek pyr - fire). Many of these methods have been known since ancient times. On turn of XIX-XX centuries begin to develop hydrometallurgical methods of obtaining metals (in Greek hydor - water). With these methods, the components of the ore are transferred into an aqueous solution and the metal is then isolated by electrolytic or chemical reduction. This is how copper is obtained, for example. Copper ore, containing copper (II) oxide CuO, is treated with dilute sulfuric acid:

To reduce copper, the resulting solution of copper (II) sulfate is either subjected to electrolysis or the solution is exposed to iron powder.

The hydrometallurgical method has a great future, as it makes it possible to obtain a product without extracting ore from the ground.

2. Types of synthetic rubbers, their properties and applications.

3. Experiment. Obtaining the named gaseous substance and carrying out reactions characterizing its properties; (carbon dioxide)

CO2 is a typical acidic oxide: it reacts with alkalis (for example, it causes cloudiness in lime water), with basic oxides and water.

Carbon dioxide is produced by reacting carbonic acid salts - carbonates with solutions of hydrochloric, nitric and even acetic acid. In the laboratory, carbon dioxide is produced by the action of hydrochloric acid on chalk or marble:

CaC03 + 2HCl = CaCl2 + H20 + C02 this is carbon dioxide

In industry large quantities carbon dioxide is obtained by burning limestone:

CaC03 = CaO + CO2

Chemical reactions with carbon dioxide

When carbon monoxide (IV) is dissolved in water, carbonic acid H2CO3 is formed, which is very unstable and easily decomposes into its initial components - carbon dioxide and water:

CO2 + H20 -> H2CO3

It does not burn and does not support combustion (Fig. 44) and therefore is used to extinguish fires. However, magnesium continues to burn in carbon dioxide, forming an oxide and releasing carbon in the form of soot.