Diamond has an ionic crystal lattice. Crystal structure of metals

A substance, as you know, can exist in three states of aggregation: gaseous, liquid and solid (Fig. 70). For example, oxygen, which normal conditions It is a gas, at a temperature of -194 ° C it turns into a blue liquid, and at a temperature of -218.8 ° C it solidifies into a snow-like mass consisting of blue crystals.

Rice. 70.
Aggregate states of water

Solids are divided into crystalline and amorphous.

Amorphous substances do not have a clear melting point - when heated, they gradually soften and become fluid. Amorphous substances include most plastics (for example, polyethylene), wax, chocolate, plasticine, various resins and chewing gums (Fig. 71).

Rice. 71.
Amorphous substances and materials

Crystalline substances are characterized correct location their constituent particles at strictly defined points in space. When these points are connected by straight lines, a spatial frame is formed, called the crystal lattice. The points at which crystal particles are located are called lattice nodes.

At the nodes of an imaginary crystal lattice there can be monatomic ions, atoms, molecules. These particles oscillate. With an increase in temperature, the range of these oscillations increases, which, as a rule, leads to thermal expansion of bodies.

Depending on the type of particles located at the nodes of the crystal lattice, and the nature of the connection between them, four types of crystal lattices are distinguished: ionic, atomic, molecular and metallic (Table 6).

Table 6
Position of elements in Periodic system D. I. Mendeleev and types of crystal lattices of their simple substances

Simple substances formed by elements not listed in the table have a metal lattice.

Ionic crystal lattices are called, in the nodes of which there are ions. They are formed by substances with an ionic bond, which can be associated with both simple ions Na +, Cl -, and complex ones, OH -. Consequently, ionic crystal lattices have salts, bases (alkalis), some oxides. For example, a sodium chloride crystal is built from alternating positive Na + and negative Cl - ions, forming a cube-shaped lattice (Fig. 72). The bonds between the ions in such a crystal are very strong. Therefore, substances with an ionic lattice have a relatively high hardness and strength, they are refractory and non-volatile.

Rice. 72.
Ionic crystal lattice (sodium chloride)

Atomic lattices are called crystal lattices, in the nodes of which there are individual atoms. In such lattices, the atoms are interconnected by very strong covalent bonds.

Rice. 73.
Atomic crystal lattice (diamond)

This type of crystal lattice has a diamond (Fig. 73) - one of the allotropic modifications of carbon. Cut and polished diamonds are called brilliants. They are widely used in jewelry (Fig. 74).

Rice. 74.
Two imperial crowns with diamonds:
a - the crown of the British Empire; b - Great Imperial Crown of the Russian Empire

Substances with an atomic crystal lattice include crystalline boron, silicon and germanium, as well as complex substances, such as silica, quartz, sand, rock crystal, which include silicon oxide (IV) SiO 2 (Fig. 75).

Rice. 75.
Atomic crystal lattice (silicon (IV) oxide)

Most substances with an atomic crystal lattice have very high melting points (for example, for diamond it is over 3500 ° C, for silicon - 1415 ° C, for silica - 1728 ° C), they are strong and hard, practically insoluble.

Molecular lattices are called crystal lattices, at the nodes of which molecules are located. Chemical bonds in these molecules can be both covalent polar (hydrogen chloride HCl, water H 2 0), and covalent non-polar (nitrogen N 2, ozone 0 3). Despite the fact that the atoms within the molecules are bound by very strong covalent bonds, there are weak forces of intermolecular attraction between the molecules themselves. Therefore, substances with molecular crystal lattices have low hardness, low melting points, and are volatile.

Examples of substances with molecular crystal lattices are solid water - ice, solid carbon monoxide (IV) C) 2 - “dry ice” (Fig. 76), solid hydrogen chloride HCl and hydrogen sulfide H 2 S, solid simple substances formed by one- (noble gases: helium, neon, argon, krypton), two- (hydrogen H 2, oxygen O 2, chlorine Cl 2, nitrogen N 2, iodine 1 2), three- (ozone O 3), four- (white phosphorus P 4 ), eight-atom (sulfur S 7) molecules. Most solid organic compounds have molecular crystal lattices (naphthalene, glucose, sugar).

Rice. 76.
Molecular crystal lattice (carbon dioxide)

Substances with a metallic bond have metallic crystal lattices (Fig. 77). At the nodes of such lattices there are atoms and ions (either atoms or ions, into which metal atoms easily turn, giving their outer electrons to common use). Such an internal structure of metals determines their characteristic physical properties: malleability, plasticity, electrical and thermal conductivity, metallic luster.

Rice. 77.
Metallic crystal lattice (iron)

Laboratory experiment No. 13
Acquaintance with the collection of substances with different types of crystal lattice. Making models of crystal lattices

Review the collection of samples of substances given to you. Write down their formulas, characterize the physical properties and, based on them, determine the type of crystal lattice.

Assemble a model of one of the crystal lattices.

For substances having a molecular structure, the law of composition constancy discovered by the French chemist J. L. Proust (1799-1803) is valid. This law is currently formulated as follows:

Proust's law is one of the fundamental laws of chemistry. However, for substances of a nonmolecular structure, for example, ionic, this law is not always true.

Keywords and phrases

1. Solid, liquid and gaseous states of matter.
2. Solids: amorphous and crystalline.
3. Crystal lattices: ionic, atomic, molecular and metallic.
4. Physical properties of substances with various types crystal lattices.
5. The law of constancy of composition.

Work with computer

1. Refer to the electronic application. Study the material of the lesson and complete the suggested tasks.
2. Search online email addresses, which can serve as additional sources that reveal the content of the keywords and phrases of the paragraph. Offer the teacher your help in preparing a new lesson - make a report on the key words and phrases of the next paragraph.

Questions and tasks

1. In what state of aggregation will oxygen be at -205 ° C?
2. Remember the work of A. Belyaev "The seller of air" and characterize the properties of solid oxygen using its description given in the book.
3. What type of substance (crystalline or amorphous) are plastics? What properties of plastics underlie their industrial applications?
4. What type of diamond crystal lattice is it? List the physical properties of a diamond.
5. What type of crystal lattice is iodine? List the physical properties of iodine.
6. Why does the melting point of metals vary over a very wide range? To prepare an answer to this question, use additional literature.
7. Why does a product made of silicon break into pieces on impact, while a product made of lead only flattens out? In which of these cases does the destruction of a chemical bond occur, and in which does not? Why?

It is not individual atoms or molecules that enter into chemical interactions, but substances.

Our task is to get acquainted with the structure of matter.

At low temperatures, substances are in a stable solid state.

☼ The hardest substance in nature is diamond. He is considered the king of all gems and precious stones. And its very name means in Greek "indestructible." Diamonds have long been regarded as miraculous stones. It was believed that a person wearing diamonds does not know stomach diseases, poison does not affect him, he retains his memory and cheerful mood until old age, enjoys royal favor.

☼ A diamond subjected to jewelry processing - cutting, polishing, is called a diamond.

During melting, as a result of thermal vibrations, the order of the particles is violated, they become mobile, while the nature of the chemical bond is not violated. Thus, there are no fundamental differences between the solid and liquid states.

Fluidity appears in the liquid (i.e., the ability to take the shape of a vessel).

Liquid crystals were discovered at the end of the 19th century, but have been studied in the last 20-25 years. Many display devices modern technology, for example, some electronic clocks, minicomputers, run on liquid crystals.

In general, the words "liquid crystals" sound no less unusual than "hot ice". However, in fact, ice can also be hot, because. at pressures over 10,000 atm. water ice melts at temperatures above 200 0 C. The unusual combination of "liquid crystals" is that the liquid state indicates the mobility of the structure, and the crystal assumes strict order.

If a substance consists of polyatomic molecules of an elongated or lamellar shape and having an asymmetric structure, then when it melts, these molecules are oriented in a certain way relative to each other (their long axes are parallel). In this case, the molecules can freely move parallel to themselves, i.e. the system acquires the fluidity characteristic of a liquid. At the same time, the system retains an ordered structure that determines the properties characteristic of crystals.

The high mobility of such a structure makes it possible to control it by very weak influences (thermal, electrical, etc.), i.e. purposefully change the properties of a substance, including optical ones, with very little energy, which is used in modern technology.

Any chemical substance is formed by a large number of identical particles that are interconnected.

At low temperatures, when thermal motion is hindered, the particles are strictly oriented in space and form crystal lattice.

Crystal cell - This a structure with a geometrically correct arrangement of particles in space.

In the crystal lattice itself, nodes and internodal space are distinguished.

The same substance depending on the conditions (p, t,…) exists in various crystalline forms (i.e., they have different crystal lattices) - allotropic modifications that differ in properties.

For example, four modifications of carbon are known - graphite, diamond, carbyne and lonsdaleite.

☼ The fourth variety of crystalline carbon "lonsdaleite" is little known. It was found in meteorites and obtained artificially, and its structure is still being studied.

☼ Soot, coke, charcoal were classified as amorphous polymers of carbon. However, it has now become known that these are also crystalline substances.

☼ By the way, shiny black particles were found in the soot, which they called "mirror carbon". Mirror carbon is chemically inert, heat-resistant, impervious to gases and liquids, has smooth surface and absolute compatibility with living tissues.

☼ The name graphite comes from the Italian "graffito" - I write, I draw. Graphite is a dark-gray crystals with a slight metallic sheen, has a layered lattice. Separate layers of atoms in a graphite crystal, relatively weakly bonded to each other, are easily separated from each other.

TYPES OF CRYSTAL LATTICES

If the crystal growth rate is low upon cooling, a glassy state (amorphous) is formed.

1. The relationship between the position of an element in the Periodic system and the crystal lattice of its simple substance.

There is a close relationship between the position of an element in the periodic table and the crystal lattice of its corresponding elementary substance.

The simple substances of the remaining elements have a metallic crystal lattice.

FIXING

Study the lecture material, answer the following questions in writing in your notebook:

1. What is a crystal lattice?
2. What types of crystal lattices exist?
3. Describe each type of crystal lattice according to the plan: What is in the nodes of the crystal lattice, structural unit → Type of chemical bond between the particles of the node → Forces of interaction between particles of the crystal → Physical properties due to the crystal lattice → Aggregate state of matter under normal conditions → Examples

Complete the tasks on this topic:

1. What type of crystal lattice do the following substances widely used in everyday life have: water, acetic acid(CH 3 COOH), sugar (C 12 H 22 O 11), potash fertilizer (KCl), river sand (SiO 2) - melting point 1710 0 C, ammonia (NH 3), salt? Make a generalized conclusion: what properties of a substance can determine the type of its crystal lattice?
2. According to the formulas of the given substances: SiC, CS 2, NaBr, C 2 H 2 - determine the type of crystal lattice (ionic, molecular) of each compound and, based on this, describe the physical properties of each of the four substances.
   
3. Trainer number 1. "Crystal Grids"
   
4. Trainer number 2. "Test tasks"
   
5. Test (self-control):

1) Substances having a molecular crystal lattice, as a rule:

2) The concept of "molecule" not applicable in relation to the structural unit of the substance:

a). water

b). oxygen

in). diamond

G). ozone

3) The atomic crystal lattice is characteristic for:

a). aluminum and graphite

b). sulfur and iodine

in). silicon oxide and sodium chloride

G). diamond and boron

4) If a substance is highly soluble in water, has a high melting point, and is electrically conductive, then its crystal lattice:

a). molecular

b). nuclear

in). ionic

G). metallic

Topics of the USE codifier: Substances of molecular and non-molecular structure. Type of crystal lattice. The dependence of the properties of substances on their composition and structure.

Molecular Kinetic Theory

All molecules are made up of smallest particles- atoms. All currently discovered atoms are collected in the periodic table.

Atom is the smallest, chemically indivisible particle of a substance that retains its chemical properties. Atoms connect to each other chemical bonds. We have previously considered a. Be sure to study the theory on the topic: Types of chemical bonds, before studying this article!

Now let's look at how particles can combine in matter.

Depending on the location of the particles relative to each other, the properties of the substances they form can vary greatly. So, if the particles are located from each other far(the distance between the particles is much more sizes particles themselves), practically do not interact with each other, move randomly and continuously in space, then we are dealing with gas .

If the particles are located close to each other, but chaotically, more interact with each other, make intense oscillatory movements in one position, but can jump to another position, then this is a model of the structure liquids .

If the particles are located close to each other, but more orderly, and interact more among themselves, but move only within one equilibrium position, practically without moving to other position, we are dealing with solid .

Most known chemicals and mixtures can exist in solid, liquid and gaseous states. The simplest example is water. At normal conditions she is liquid, at 0 o C it freezes - it passes from a liquid state to solid, and at 100 ° C it boils - goes into gas phase- water vapor. At the same time, many substances under normal conditions are gases, liquids or solids. For example, air, a mixture of nitrogen and oxygen, is a gas under normal conditions. But at high pressure and low temperature, nitrogen and oxygen condense and pass into the liquid phase. Liquid nitrogen is actively used in industry. Sometimes isolated plasma, as well as liquid crystals, as separate phases.

Many properties of individual substances and mixtures are explained by mutual arrangement particles in space relative to each other!

This article considers properties solids , depending on their structure. Basic physical properties of solids: melting point, electrical conductivity, thermal conductivity, mechanical strength, plasticity, etc.

Melting temperature is the temperature at which a substance changes from solid to liquid and vice versa.

is the ability of a substance to deform without breaking.

Electrical conductivity is the ability of a substance to conduct current.

Current is the ordered movement of charged particles. Thus, current can be conducted only by substances in which there are moving charged particles. According to the ability to conduct current, substances are divided into conductors and dielectrics. Conductors are substances that can conduct current (i.e. contain mobile charged particles). Dielectrics are substances that practically do not conduct current.

In a solid, the particles of a substance can be located chaotically, or more orderly about. If the particles of a solid are located in space chaotically, the substance is called amorphous. Examples amorphous substances – coal, mica glass.

If the particles of a solid are arranged in space in an orderly manner, i.e. form repeating three-dimensional geometric structures, such a substance is called crystal, and the structure itself crystal lattice . Most of the substances known to us are crystals. The particles themselves are located in nodes crystal lattice.

Crystalline substances are distinguished, in particular, by type of chemical bond between particles in a crystal - atomic, molecular, metallic, ionic; according to the geometric shape of the simplest cell of the crystal lattice - cubic, hexagonal, etc.

Depending on the type of particles forming a crystal lattice , distinguish atomic, molecular, ionic and metallic crystal structure .

Atomic crystal lattice

An atomic crystal lattice is formed when there are atoms. Atoms are connected to each other covalent chemical bonds. Accordingly, such a crystal lattice will be very durable, it is not easy to destroy it. An atomic crystal lattice can be formed by atoms with a high valency, i.e. with a large number of bonds with neighboring atoms (4 or more). As a rule, these are non-metals: simple substances - silicon, boron, carbon (allotropic modifications of diamond, graphite), and their compounds (borocarbon, silicon (IV) oxide, etc..). Since a predominantly covalent chemical bond occurs between non-metals, free electrons(as well as other charged particles) in substances with an atomic crystal lattice in most cases no. Therefore, these substances are usually perform very poorly electricity, i.e. are dielectrics. These are general patterns, of which there are a number of exceptions.

Communication between particles in atomic crystals: .

At the nodes of the crystal with atomic crystal structure arranged atoms.

Phase state atomic crystals under normal conditions: as a rule, solids .

Substances, which form atomic crystals in the solid state:

1. Simple substances high valency (located in the middle of the periodic table): boron, carbon, silicon, etc.
2. Complex substances formed by these non-metals: silica (silicon oxide, quartz sand) SiO 2 ; silicon carbide (corundum) SiC; boron carbide, boron nitride, etc.

Physical properties of substances with an atomic crystal lattice:

— strength;

- refractoriness (high melting point);

- low electrical conductivity;

- low thermal conductivity;

— chemical inertness(inactive substances);

- insolubility in solvents.

Molecular crystal lattice is a lattice whose nodes are molecules. hold the molecules in the crystal weak forces of intermolecular attraction (van der Waals forces, hydrogen bonds, or electrostatic attraction). Accordingly, such a crystal lattice, as a rule, quite easy to destroy. Substances with a molecular crystal lattice - flimsy, fragile. How more power attraction between molecules, the higher the melting point of the substance. As a rule, the melting points of substances with a molecular crystal lattice are not higher than 200-300K. Therefore, under normal conditions, most substances with a molecular crystal lattice exist in the form gases or liquids. The molecular crystal lattice, as a rule, is formed in solid form by acids, oxides of non-metals, other binary compounds of non-metals, simple substances that form stable molecules (oxygen O 2, nitrogen N 2, water H 2 O, etc.), organic substances. As a rule, these are substances with a covalent polar (rarely non-polar) bond. Because electrons are involved in chemical bonds, substances with a molecular crystal lattice - dielectrics, poor conductors of heat.

Communication between particles in molecular crystals: m intermolecular, electrostatic, or intermolecular forces of attraction.

At the nodes of the crystal with molecular crystal structure arranged molecules.

Phase state molecular crystals under normal conditions: gases, liquids and solids.

Substances, forming in the solid state molecular crystals:

1. Simple non-metal substances that form small, strong molecules (O 2 , N 2 , H 2 , S 8 and others);
2. Complex substances (compounds of non-metals) with covalent polar bonds (except for oxides of silicon and boron, compounds of silicon and carbon) - water H 2 O, sulfur oxide SO 3, etc.
3. Monatomic rare gases (helium, neon, argon, krypton and etc.);
4. Most organic substances that do not have ionic bonds — methane CH 4, benzene C 6 H 6, etc.

Physical properties substances with a molecular crystal lattice:

- fusibility (low melting point):

— high compressibility;

- molecular crystals in solid form, as well as in solutions and melts, do not conduct current;

- phase state under normal conditions - gases, liquids, solids;

- high volatility;

- low hardness.

Ionic crystal lattice

If there are charged particles at the nodes of the crystal - ions, we can talk about ionic crystal lattice . As a rule, with ionic crystals alternate positive ions(cations) and negative ions(anions), so the particles in the crystal are retained forces of electrostatic attraction . Depending on the type of crystal and the type of ions that form the crystal, such substances can be quite strong and tough. In the solid state, there are, as a rule, no mobile charged particles in ionic crystals. But when the crystal is dissolved or melted, the ions are released and can move under the action of an external electric field. Those. conduct current only solutions or melts ionic crystals. The ionic crystal lattice is characteristic of substances with ionic chemical bond. Examples such substances salt NaCl calcium carbonate- CaCO 3, etc. The ionic crystal lattice, as a rule, is formed in the solid phase salts, bases, as well as metal oxides and binary compounds of metals and non-metals.

Communication between particles in ionic crystals: .

At the nodes of the crystal with an ionic lattice ions.

Phase state ionic crystals under normal conditions: usually solids.

Chemical substances with an ionic crystal lattice:

1. Salts (organic and inorganic), including ammonium salts (For example, ammonium chloride NH4Cl);
2. grounds;
3. metal oxides;
4. Binary compounds containing metals and non-metals.

Physical properties of substances with an ionic crystal structure:

- high melting point (refractory);

- solutions and melts of ionic crystals - current conductors;

- most compounds are soluble in polar solvents (water);

- solid phase state in most compounds under normal conditions.

And, finally, metals are characterized by a special type of spatial structure - metal crystal lattice, which is due metallic chemical bond . Metal atoms hold valence electrons rather weakly. In a crystal formed by a metal, the following processes occur simultaneously: some atoms donate electrons and become positively charged ions; these electrons move randomly in the crystal; some of the electrons are attracted to the ions. These processes occur simultaneously and randomly. Thus, ions appear , as in the formation of an ionic bond, and common electrons are formed as in the formation of a covalent bond. Free electrons move randomly and continuously throughout the volume of the crystal, like a gas. Therefore, they are sometimes called electron gas ". Due to the presence a large number mobile charged particles metals conduct electricity, heat. The melting point of metals varies greatly. Metals are also characterized peculiar metallic luster, malleability, i.e. the ability to change shape without destruction under strong mechanical stress, tk. chemical bonds while not being destroyed.

Communication between particles : .

At the nodes of the crystal with metal grating located metal ions and atoms.

Phase state metals under normal conditions: usually solids(exception - mercury, liquid under normal conditions).

Chemical substances with a metal crystal lattice - simple substances - metals.

Physical properties of substances with a metal crystal lattice:

– high thermal and electrical conductivity;

- malleability and plasticity;

- metallic luster;

— metals are generally insoluble in solvents;

Most metals are solids under normal conditions.

Comparison of the properties of substances with different crystal lattices

The type of crystal lattice (or the absence of a crystal lattice) makes it possible to evaluate the basic physical properties of a substance. For a rough comparison of typical physical properties compounds with different crystal lattices it is very convenient to use chemical substances with characteristic properties. For a molecular lattice, for example, carbon dioxide, for the atomic crystal lattice - diamond, for metal - copper, and for the ionic crystal lattice - salt, sodium chloride NaCl.

Summary table on the structures of simple substances formed chemical elements from the main subgroups of the periodic table (the elements of the secondary subgroups are metals, therefore, they have a metallic crystal lattice).

The final table of the relationship of the properties of substances with the structure:

The molecular structure has

1) silicon(IV) oxide

2) barium nitrate

3) sodium chloride

4) carbon monoxide (II)

Explanation.

The structure of a substance is understood from which particles of molecules, ions, atoms its crystal lattice is built. Substances with ionic and metallic bonds have a non-molecular structure. Substances in whose molecules atoms are connected by covalent bonds can have molecular and atomic crystal lattices. Atomic crystal lattices: C (diamond, graphite), Si, Ge, B, SiO 2 , SiC (carborundum), BN, Fe 3 C, TaC, red and black phosphorus. This group includes substances, as a rule, solid and refractory substances.

Silicon oxide (IV) - covalent bonds, solid, refractory substance, atomic crystal lattice. Barium nitrate and sodium chloride substances with ionic bonds - the crystal lattice is ionic. Carbon monoxide (II) is a gas in a molecule of covalent bonds, which means that this is the correct answer, the crystal lattice is molecular.

Answer: 4

Source: Demo version of the USE-2012 in chemistry.

In solid form, the molecular structure is

1) silicon(IV) oxide

2) calcium chloride

3) copper (II) sulfate

Explanation.

The structure of a substance is understood from which particles of molecules, ions, atoms its crystal lattice is built. Substances with ionic and metallic bonds have a non-molecular structure. Substances in whose molecules atoms are connected by covalent bonds can have molecular and atomic crystal lattices. Atomic crystal lattices: C (diamond, graphite), Si, Ge, B, SiO 2 , SiC (carborundum), BN, Fe 3 C, TaC, red and black phosphorus. This group includes substances, as a rule, solid and refractory substances.

Substances with a molecular crystal lattice have lower boiling points than all other substances. According to the formula, it is necessary to determine the type of bond in the substance, and then determine the type of crystal lattice. Silicon oxide (IV) - covalent bonds, solid, refractory substance, atomic crystal lattice. Calcium chloride and copper sulfate are substances with ionic bonds - the crystal lattice is ionic. There are covalent bonds in the iodine molecule, and it easily sublimes, so this is the correct answer, the crystal lattice is molecular.

Answer: 4

Source: Demo version of the USE-2013 in chemistry.

1) carbon monoxide (II)

3) magnesium bromide

Explanation.

Substances with ionic and metallic bonds have a non-molecular structure. Substances in whose molecules atoms are connected by covalent bonds can have molecular and atomic crystal lattices. Atomic crystal lattices: C (diamond, graphite), Si, Ge, B, SiO2, SiC (carborundum), BN, Fe3 C, TaC, red and black phosphorus. This group includes substances, as a rule, solid and refractory substances.

Answer: 3

Source: USE in Chemistry 06/10/2013. main wave. Far East. Option 1.

The ionic crystal lattice has

2) carbon monoxide (II)

4) magnesium bromide

Explanation.

Substances with ionic and metallic bonds have a non-molecular structure. Substances in whose molecules atoms are connected by covalent bonds can have molecular and atomic crystal lattices. Atomic crystal lattices: C (diamond, graphite), Si, Ge, B, SiO2, CaC2, SiC (carborundum), BN, Fe3 C, TaC, red and black phosphorus. This group includes substances, as a rule, solid and refractory substances.

Substances with a molecular crystal lattice have lower boiling points than all other substances. According to the formula, it is necessary to determine the type of bond in the substance, and then determine the type of crystal lattice.

Magnesium bromide has an ionic crystal lattice.

Answer: 4

Source: USE in Chemistry 06/10/2013. main wave. Far East. Option 2.

Sodium sulfate has a crystal lattice

1) metal

3) molecular

4) nuclear

Explanation.

Substances with a molecular crystal lattice have lower boiling points than all other substances. According to the formula, it is necessary to determine the type of bond in the substance, and then determine the type of crystal lattice.

Sodium sulfate is a salt having an ionic crystal lattice.

Answer: 2

Source: USE in Chemistry 06/10/2013. main wave. Far East. Option 3.

Each of the two substances has a non-molecular structure:

1) nitrogen and diamond

2) potassium and copper

3) water and sodium hydroxide

4) chlorine and bromine

Explanation.

Substances with ionic and metallic bonds have a non-molecular structure. Substances in whose molecules atoms are connected by covalent bonds can have molecular and atomic crystal lattices. Atomic crystal lattices: C (diamond, graphite), Si, Ge, B, SiO2, SiC (carborundum), BN, red and black phosphorus. This group includes substances, as a rule, solid and refractory substances.

Substances with a molecular crystal lattice have lower boiling points than all other substances. According to the formula, it is necessary to determine the type of bond in the substance, and then determine the type of crystal lattice.

Of these substances, only diamond, potassium, copper and sodium hydroxide have a non-molecular structure.

Answer: 2

Source: USE in Chemistry 06/10/2013. main wave. Far East. Option 4.

A substance with an ionic type of crystal lattice is

3) acetic acid

4) sodium sulfate

Explanation.

Substances with ionic and metallic bonds have a non-molecular structure. Substances in whose molecules atoms are connected by covalent bonds can have molecular and atomic crystal lattices. Atomic crystal lattices: C (diamond, graphite), Si, Ge, B, SiO2, CaC2, SiC (carborundum), BN, Fe3 C, TaC, red and black phosphorus. This group includes substances, as a rule, solid and refractory substances.

Substances with a molecular crystal lattice have lower boiling points than all other substances. According to the formula, it is necessary to determine the type of bond in the substance, and then determine the type of crystal lattice.

Sodium sulfate has an ionic crystal lattice.

Answer: 4

Source: USE in Chemistry 06/10/2013. main wave. Siberia. Option 1.

The metallic crystal lattice is characteristic of

2) white phosphorus

3) aluminum oxide

4) calcium

Explanation.

The metallic crystal lattice is characteristic of metals, such as calcium.

Answer: 4

Source: USE in Chemistry 06/10/2013. main wave. Ural. Option 1.

Maxim Avramchuk 22.04.2015 16:53

All metals except mercury have a metallic crystal lattice. Can you tell me what is the crystal lattice of mercury and amalgam?

Alexander Ivanov

Mercury in the solid state also has a metallic crystal lattice

2) calcium oxide

4) aluminum

Explanation.

Substances with ionic and metallic bonds have a non-molecular structure. Substances in whose molecules atoms are connected by covalent bonds can have molecular and atomic crystal lattices. Atomic crystal lattices: C (diamond, graphite), Si, Ge, B, SiO2, CaC2, SiC (carborundum), BN, Fe3 C, TaC, red and black phosphorus. This group includes substances, as a rule, solid and refractory substances.

Substances with a molecular crystal lattice have lower boiling points than all other substances. According to the formula, it is necessary to determine the type of bond in the substance, and then determine the type of crystal lattice.

Calcium oxide has an ionic crystal lattice.

Answer: 2

Source: USE in Chemistry 06/10/2013. main wave. Siberia. Option 2.

The molecular crystal lattice in solid state It has

1) sodium iodide

2) sulfur oxide (IV)

3) sodium oxide

4) iron(III) chloride

Explanation.

Substances with ionic and metallic bonds have a non-molecular structure. Substances in whose molecules atoms are connected by covalent bonds can have molecular and atomic crystal lattices. Atomic crystal lattices: C (diamond, graphite), Si, Ge, B, SiO2, CaC2, SiC (carborundum), BN, Fe3 C, TaC, red and black phosphorus. This group includes substances, as a rule, solid and refractory substances.

Substances with a molecular crystal lattice have lower boiling points than all other substances. According to the formula, it is necessary to determine the type of bond in the substance, and then determine the type of crystal lattice.

Among the above substances, all except sulfur oxide (IV) have an ionic crystal lattice, and it has a molecular one.

Answer: 2

Source: USE in Chemistry 06/10/2013. main wave. Siberia. Option 4.

The ionic crystal lattice has

3) sodium hydride

4) nitric oxide (II)

Explanation.

Substances with ionic and metallic bonds have a non-molecular structure. Substances in whose molecules atoms are connected by covalent bonds can have molecular and atomic crystal lattices. Atomic crystal lattices: C (diamond, graphite), Si, Ge, B, SiO2, CaC2, SiC (carborundum), BN, Fe3 C, TaC, red and black phosphorus. This group includes substances, as a rule, solid and refractory substances.

Substances with a molecular crystal lattice have lower boiling points than all other substances. According to the formula, it is necessary to determine the type of bond in the substance, and then determine the type of crystal lattice.

Sodium hydride has an ionic crystal lattice.

Answer: 3

Source: USE in Chemistry 06/10/2013. main wave. Ural. Option 5.

For substances with a molecular crystal lattice, a characteristic property is

1) refractoriness

2) low boiling point

3) high melting point

4) electrical conductivity

Explanation.

Substances with a molecular crystal lattice have lower boiling points than all other substances. Answer: 2

Answer: 2

Source: USE in Chemistry 06/10/2013. main wave. Centre. Option 1.

For substances with a molecular crystal lattice characteristic property is an

1) refractoriness

2) high boiling point

3) low melting point

4) electrical conductivity

Explanation.

Substances with a molecular crystal lattice have lower melting and boiling points than all other substances.

Answer: 3

Source: USE in Chemistry 06/10/2013. main wave. Centre. Option 2.

The molecular structure has

1) hydrogen chloride

2) potassium sulfide

3) barium oxide

4) calcium oxide

Explanation.

Substances with ionic and metallic bonds have a non-molecular structure. Substances in whose molecules atoms are connected by covalent bonds can have molecular and atomic crystal lattices. Atomic crystal lattices: C (diamond, graphite), Si, Ge, B, SiO2, CaC2, SiC (carborundum), BN, Fe3 C, TaC, red and black phosphorus. This group includes substances, as a rule, solid and refractory substances.

Substances with a molecular crystal lattice have lower boiling points than all other substances. According to the formula, it is necessary to determine the type of bond in the substance, and then determine the type of crystal lattice.

Of these substances, all have an ionic crystal lattice, except for hydrogen chloride.

Answer: 1

Source: USE in Chemistry 06/10/2013. main wave. Centre. Option 5.

The molecular structure has

1) silicon(IV) oxide

2) barium nitrate

3) sodium chloride

4) carbon monoxide (II)

Explanation.

Substances with ionic and metallic bonds have a non-molecular structure. Substances in whose molecules atoms are connected by covalent bonds can have molecular and atomic crystal lattices. Atomic crystal lattices: C (diamond, graphite), Si, Ge, B, SiO2, CaC2, SiC (carborundum), BN, Fe3 C, TaC, red and black phosphorus. This group includes substances, as a rule, solid and refractory substances.

Substances with a molecular crystal lattice have lower boiling points than all other substances. According to the formula, it is necessary to determine the type of bond in the substance, and then determine the type of crystal lattice.

Among these substances, carbon monoxide has a molecular structure.

Answer: 4

Source: Demo version of the USE-2014 in chemistry.

The molecular structure is

1) ammonium chloride

2) cesium chloride

3) iron(III) chloride

4) hydrogen chloride

Explanation.

The structure of a substance is understood from which particles of molecules, ions, atoms its crystal lattice is built. Substances with ionic and metallic bonds have a non-molecular structure. Substances in whose molecules atoms are connected by covalent bonds can have molecular and atomic crystal lattices. Atomic crystal lattices: C (diamond, graphite), Si, Ge, B, SiO2, SiC (carborundum), BN, Fe3C, TaC, red and black phosphorus. This group includes substances, as a rule, solid and refractory substances.

Substances with a molecular crystal lattice have lower boiling points than all other substances. According to the formula, it is necessary to determine the type of bond in the substance, and then determine the type of crystal lattice.

1) ammonium chloride - ionic structure

2) cesium chloride - ionic structure

3) iron(III) chloride - ionic structure

4) hydrogen chloride - molecular structure

Answer: 4

Which of the chlorine compounds has the highest melting point?

Answer: 3

Which of the oxygen compounds has the highest melting point?

Answer: 3

Alexander Ivanov

No. This is an atomic crystal lattice

Igor Srago 22.05.2016 14:37

Since the USE teaches that the bond between the atoms of metals and non-metals is ionic, aluminum oxide must form an ionic crystal. And substances of an ionic structure, too (as well as atomic) have a melting point higher than molecular substances.

Anton Golyshev

Substances with an atomic crystal lattice are better to just learn.

For substances with a metallic crystal lattice is uncharacteristic

1) fragility

2) plasticity

3) high electrical conductivity

4) high thermal conductivity

Explanation.

Metals are characterized by plasticity, high electrical and thermal conductivity, but fragility is not typical for them.

Answer: 1

Source: USE 05/05/2015. Early wave.

Explanation.

Substances in whose molecules atoms are connected by covalent bonds can have molecular and atomic crystal lattices. Atomic crystal lattices: C (diamond, graphite), Si, Ge, B, SiO2, SiC (carborundum), BN, Fe3C, TaC, red and black phosphorus. This group includes substances, as a rule, solid and refractory substances.

Answer: 1

The molecular crystal lattice has

Explanation.

Substances with ionic (BaSO 4) and metallic bonds have a non-molecular structure.

Substances whose atoms are connected by covalent bonds can have molecular and atomic crystal lattices.

Atomic crystal lattices: C (diamond, graphite), Si, Ge, B, SiO 2, SiC (carborundum), B 2 O 3, Al 2 O 3.

Substances that are gaseous under normal conditions (O 2, H 2, NH 3, H 2 S, CO 2), as well as liquid (H 2 O, H 2 SO 4) and solid, but fusible (S, glucose), have a molecular structure

Therefore, the molecular crystal lattice has - carbon dioxide.

Answer: 2

The atomic crystal lattice has

1) ammonium chloride

2) cesium oxide

3) silicon(IV) oxide

4) crystalline sulfur

Explanation.

Substances with ionic and metallic bonds have a non-molecular structure.

Substances in whose molecules atoms are connected by covalent bonds can have molecular and atomic crystal lattices. Atomic crystal lattices: C (diamond, graphite), Si, Ge, B, SiO2, SiC (carborundum), BN, Fe3C, TaC, red and black phosphorus. The rest refer to substances with a molecular crystal lattice.

Therefore, silicon (IV) oxide has an atomic crystal lattice.

Answer: 3

A solid brittle substance with a high melting point, the solution of which conducts an electric current, has a crystal lattice

2) metal

3) nuclear

4) molecular

Explanation.

Such properties are characteristic of substances with an ionic crystal lattice.

Answer: 1

Which silicon compound has a molecular crystal lattice in the solid state?

Solids, as a rule, have a crystalline structure. It is characterized by the correct arrangement of particles at strictly defined points in space. When these points are mentally connected by intersecting straight lines, a spatial frame is formed, which is called crystal lattice. The points where the particles are placed are called lattice nodes. The nodes of an imaginary lattice can contain ions, atoms or molecules. They make oscillatory movements. With an increase in temperature, the amplitude of oscillations increases, which manifests itself in the thermal expansion of bodies.

Depending on the type of particles and the nature of the bond between them, 4 types of crystal lattices are distinguished: ionic (NaCl, KCl), atomic, molecular and metallic.

Crystal lattices made up of ions are called ionic. They are formed by substances with ionic bonds. An example is a sodium chloride crystal in which each sodium ion is surrounded by 6 chloride ions and each chloride ion by 6 sodium ions.

Crystal lattice of NaCl

The number of nearest neighboring particles closely adjacent to a given particle in a crystal or a single molecule is called focal number.

In the NaCl lattice, the coordination numbers of both ions are equal to 6. And so, in the NaCl crystal, it is impossible to isolate individual salt molecules. They are not here. The whole crystal should be considered as a giant macromolecule consisting of an equal number of Na + and Cl - ions, Na n Cl n – where n is a large number. The bonds between ions in such a crystal are very strong. Therefore, substances with an ionic lattice have a relatively high hardness. They are refractory and low volatility.

The melting of ionic crystals leads to a violation of the geometrically correct orientation of the ions relative to each other and a decrease in the strength of the bond between them. Therefore, their melts conduct electric current. Ionic compounds tend to readily dissolve in liquids composed of polar molecules, such as water.

Crystal lattices, at the nodes of which there are individual atoms, are called atomic. Atoms in such lattices are interconnected by strong covalent bonds. An example is diamond - one of the modifications of carbon. A diamond is made up of carbon atoms, each of which is bonded to 4 neighboring atoms. The coordination number of carbon in diamond is 4. Substances with an atomic crystal lattice have a high melting point (diamond has over 3500 ° C), are strong and hard, and practically insoluble in water.

Crystal lattices consisting of molecules (polar and non-polar) are called molecular. Molecules in such lattices are interconnected by relatively weak intermolecular forces. Therefore, substances molecular lattice have low hardness and low melting point, are insoluble or slightly soluble in water, their solutions almost do not conduct electric current. Examples of them are ice, solid CO 2 (“dry ice”), halogens, crystals of hydrogen, oxygen, nitrogen, noble gases, etc.

Valence

An important quantitative characteristic showing the number of interacting atoms in the resulting molecule is valence- the property of atoms of one element to attach a certain number of atoms of other elements.

Quantitatively, valence is determined by the number of hydrogen atoms that a given element can attach or replace. So, for example, in hydrofluoric acid(HF) fluorine is monovalent, in ammonia (NH 3) nitrogen is trivalent, in silicon hydrogen (SiH 4 - silane) silicon is tetravalent, etc.

Later, with the development of ideas about the structure of atoms, the valence of elements began to be associated with the number of unpaired electrons (valence), due to which the bond between atoms is carried out. Thus, valence is determined by the number of unpaired electrons in an atom that take part in the formation of a chemical bond (in the ground or excited state). In the general case, valence is equal to the number of electron pairs that bind a given atom to atoms of other elements.