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Substances have a molecular crystal lattice. Crystal lattices – Knowledge Hypermarket

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, and 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, usually solid and refractory substances.

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

Answer: 4

Source: Demo version of the Unified State Exam 2012 in chemistry.

In solid form, the molecular structure has

1) silicon(IV) oxide

2) calcium chloride

3) copper (II) sulfate

Explanation.

Substances with a molecular crystal lattice have lower boiling points than all other substances. Using 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. The iodine molecule has covalent bonds, and it easily sublimes, which means this is the correct answer, the crystal lattice is molecular.

Answer: 4

Source: Demo version of the Unified State Exam 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, usually solid and refractory substances.

Answer: 3

Source: Unified State Exam in Chemistry 06/10/2013. Main wave. Far East. Option 1.

Has an ionic crystal lattice

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, usually solid and refractory substances.

Magnesium bromide has an ionic crystal lattice.

Answer: 4

Source: Unified State Exam in Chemistry 06/10/2013. Main wave. Far East. Option 2.

Sodium sulfate has a crystal lattice

1) metal

3) molecular

4) atomic

Explanation.

Sodium sulfate is a salt that has an ionic crystal lattice.

Answer: 2

Source: Unified State Exam in Chemistry 06/10/2013. Main wave. Far East. Option 3.

Each of 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, usually solid and refractory substances.

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

Answer: 2

Source: Unified State Exam in Chemistry 06/10/2013. Main wave. Far East. Option 4.

A substance with an ionic 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, usually solid and refractory substances.

Sodium sulfate has an ionic crystal lattice.

Answer: 4

Source: Unified State Exam in Chemistry 06/10/2013. Main wave. Siberia. Option 1.

The metal crystal lattice is characteristic of

2) white phosphorus

3) aluminum oxide

4) calcium

Explanation.

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

Answer: 4

Source: Unified State Exam 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. Could you tell me what kind of crystal lattice does mercury and amalgam have?

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, usually solid and refractory substances.

Calcium oxide has an ionic crystal lattice.

Answer: 2

Source: Unified State Exam in Chemistry 06/10/2013. Main wave. Siberia. Option 2.

Has a molecular crystal lattice in the solid state

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, usually solid and refractory substances.

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

Answer: 2

Source: Unified State Exam in Chemistry 06/10/2013. Main wave. Siberia. Option 4.

Has an ionic crystal lattice

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, usually solid and refractory substances.

Sodium hydride has an ionic crystal lattice.

Answer: 3

Source: Unified State Exam 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: Unified State Exam in Chemistry 06/10/2013. Main wave. Center. Option 1.

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

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: Unified State Exam in Chemistry 06/10/2013. Main wave. Center. 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, usually solid and refractory substances.

Of the above substances, all have an ionic crystal lattice except hydrogen chloride.

Answer: 1

Source: Unified State Exam in Chemistry 06/10/2013. Main wave. Center. 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, usually solid and refractory substances.

Among the listed substances, carbon monoxide has a molecular structure.

Answer: 4

Source: Demo version of the Unified State Exam 2014 in chemistry.

The substance of 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, and 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, usually solid and refractory substances.

1) ammonium chloride - ionic structure

2) cesium chloride - ionic structure

3) iron(III) chloride - ionic structure

4) hydrogen chloride - molecular structure

Answer: 4

Which chlorine compound has the highest melting point?

Answer: 3

Which oxygen compound 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 Unified State Examination teaches that the bond between metal and non-metal atoms is ionic, aluminum oxide should form an ionic crystal. And substances with an ionic structure (like atomic ones) also have a melting point higher than molecular substances.

Anton Golyshev

It is better to simply learn substances with an atomic crystal lattice.

Uncharacteristic for substances with a metal crystal lattice

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: Unified State Exam 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, usually solid and refractory substances.

Answer: 1

Has a molecular crystal lattice

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, carbon dioxide has a molecular crystal lattice.

Answer: 2

Has an atomic crystal lattice

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 electric current, has a crystal lattice

2) metal

3) atomic

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?

Instructions

As you can easily guess from the name itself, the metal type of lattice is found in metals. These substances are usually characterized by a high melting point, metallic luster, hardness, and are good conductors of electric current. Remember that lattice sites of this type contain either neutral atoms or positively charged ions. In the spaces between the nodes there are electrons, the migration of which ensures the high electrical conductivity of such substances.

Ionic type of crystal lattice. It should be remembered that it is also inherent in salts. Characteristic - crystals of the well-known table salt, sodium chloride. Positively and negatively charged ions alternate alternately at the sites of such lattices. Such substances are usually refractory and have low volatility. As you might guess, they have ion type.

The atomic type of crystal lattice is inherent in simple substances - nonmetals, which, when normal conditions are solid bodies. For example, sulfur, phosphorus,... At the sites of such lattices there are neutral atoms connected to each other by covalent chemical bonds. Such substances are characterized by refractoriness and insolubility in water. Some (for example, carbon in the form) have exceptionally high hardness.

Finally, the last type of lattice is molecular. It is found in substances that are under normal conditions in liquid or gaseous form. As again can be easily understood from, at the nodes of such lattices there are molecules. They can be either non-polar (for simple gases such as Cl2, O2) or polar (the most famous example– water H2O). Substances with this type of lattice do not conduct current, are volatile, and have low melting points.

Sources:

grating type

Temperature melting of a solid is measured to determine its purity. Impurities in a pure substance usually lower the temperature melting or increase the interval over which the compound melts. The capillary method is a classic method for controlling impurities.

You will need

- test substance;
- glass capillary, sealed at one end (diameter 1 mm);
- glass tube with a diameter of 6-8 mm and a length of at least 50 cm;
- heated block.

Instructions

Grind the pre-dried test substance in a mortar until it is fine. Carefully take the capillary and immerse the open end into the substance, while some of it should fall into the capillary.

Place the glass tube vertically on a hard surface and drop the capillary through it several times, sealed end down. This helps compact the substance. To determine the temperature, the column of the substance in the capillary should be about 2-5 mm.

Place the capillary thermometer in the heated block and observe the changes in the test substance as the temperature increases. Before and during heating, the thermometer should not touch the walls of the block or other very hot surfaces, otherwise it may burst.

Note the temperature at which the first drops appear in the capillary (beginning melting), and the temperature at which the last substances disappear (end melting). In this interval, the substance begins to decrease until it completely transforms into a liquid state. When performing the analysis, also look for changes or decomposition of the substance.

Repeat measurements 1-2 more times. Present the results of each measurement in the form of the corresponding temperature interval during which the substance passes from solid to liquid. At the end of the analysis, make a conclusion about the purity of the test substance.

Video on the topic

In crystals, chemical particles (molecules, atoms and ions) are arranged in a certain order; under certain conditions they form regular symmetrical polyhedra. There are four types crystal lattices- ionic, atomic, molecular and metallic.

Crystals

The crystalline state is characterized by the presence of long-range order in the arrangement of particles, as well as the symmetry of the crystal lattice. Solid crystals are three-dimensional formations in which the same structural element is repeated in all directions.

The correct shape of crystals is determined by their internal structure. If you replace molecules, atoms and ions in them with points instead of the centers of gravity of these particles, you get a three-dimensional regular distribution - . The repeating elements of its structure are called elementary cells, and the points are called nodes of the crystal lattice. There are several types of crystals depending on the particles that form them, as well as the nature of the chemical bond between them.

Ionic crystal lattices

Ionic crystals form anions and cations, between which there are. This type of crystal includes salts of most metals. Each cation is attracted to the anion and repelled by other cations, so it is impossible to isolate single molecules in an ionic crystal. The crystal can be considered as one huge one, and its size is not limited; it is capable of attaching new ions.

Atomic crystal lattices

In atomic crystals, individual atoms are united by covalent bonds. Like ionic crystals, they can also be thought of as huge molecules. At the same time, atomic crystals are very hard and durable, and do not conduct electricity and heat well. They are practically insoluble and are characterized by low reactivity. Substances with atomic lattices melt at very high temperatures Oh.

Molecular crystals

Molecular crystal lattices are formed from molecules whose atoms are united by covalent bonds. Because of this, weak molecular forces act between molecules. Such crystals are characterized by low hardness, low melting point and high fluidity. The substances that they form, as well as their melts and solutions, do not conduct electric current well.

Metal crystal lattices

In metal crystal lattices, atoms are arranged with maximum density, their bonds are delocalized, and they extend throughout the entire crystal. Such crystals are opaque, have a metallic luster, are easily deformed, and are good conductors of electricity and heat.

This classification describes only limiting cases, most crystals inorganic substances belongs to intermediate types - molecular-covalent, covalent, etc. As an example, a graphite crystal has covalent-metallic bonds inside each layer, and molecular bonds between the layers.

Sources:

alhimik.ru, Solids

Diamond is a mineral that belongs to one of the allotropic modifications of carbon. Distinctive feature its high hardness, which rightfully earns it the title of the hardest substance. Diamond is a fairly rare mineral, but at the same time it is the most widespread. Its exceptional hardness finds its application in mechanical engineering and industry.

Instructions

Diamond has an atomic crystal lattice. The carbon atoms that form the basis of the molecule are arranged in the form of a tetrahedron, which is why diamond has such high strength. All atoms are connected by strong covalent bonds, which are formed based on the electronic structure of the molecule.

The carbon atom has sp3 hybridized orbitals that are at an angle of 109 degrees and 28 minutes. The overlap of hybrid orbitals occurs in a straight line in the horizontal plane.

Thus, when the orbitals overlap at such an angle, a centered

Crystal cell- a system of points located in equal, parallel oriented vertices and parallelepipeds adjacent along the faces without gaps, filling the space of points called nodes, straight lines - rows, planes - grids, parallelepipeds are called elementary cells.

Types of crystal lattices: atomic - if atoms are located at the nodes, ionic - if ions are located at the nodes, molecular - if molecules are located at the nodes

2. Properties of crystalline substances - homogeneity, anisotropy, ability to self-cut.

Uniformity- two identical elementary volumes of a substance, parallel oriented in space, but isolated at different points of the substance, absolutely identical in properties (beryl - tourmaline).

Anisotropy- in different directions of the crystal lattice in non-parallel directions, many properties (for example, strength, hardness, refractive index) are different.

Ability to self-destruct– the property of crystals, when growing freely, to form regularly faceted polyhedra.

Property of constancy of dihedral nodes– the angles between the corresponding faces and edges in all crystals of the same substance are the same.

3. The concept of syngony. What categories are syngonies divided into?

Syngony is a set of types of symmetries that have 1 or several common symmetry elements, with an equal number of unit directions. The cell is characterized by the relationships between the a, b, and c axes and the cell angles.

There are 7 Divided into:

Lowest( do not have symmetry axes higher than the second order)

Average ( they have one axis of symmetry of higher order)

Single directions– directions that are not repeated in crystals.

Being the largest classification division in the symmetry of crystals, each symmetry group includes several point groups of symmetries and Bravais lattices.

4.Simple shapes and combinations. The physical meaning of isolating simple forms in a crystal.

Based on their appearance, crystals are divided into simple shapes and combinations. Simple forms– crystals obtained from one face by the action of an element of symmetry on it.

Elements of symmetry:

geometric image

plane of symmetry- a plane perpendicular to the image, dividing the figure into 2 parts, corresponding as an object and its mirror image.

Axis of symmetry- this is a straight line perpendicular to the image, when rotated around 360 o the figure is aligned with itself n times.

Center of symmetry- a point inside a crystal characterized by the fact that each straight line drawn through it meets identical points on both sides at equal distances.

Combinations- crystals consisting of faces of various types, differing in shape and size. Formed by a combination of two or more simple forms. There are as many types of faces on a uniformly developed crystal as there are simple forms in it.

Selecting faces of different types has physical meaning , since different faces grow at different rates and have different properties (hardness, density, refractive index).

Simple forms are open and closed. A closed simple form, with the help of faces of the same type, independently closes the space (tetragonal dipyramid), an open simple form can close the space only in combination with other simple forms (tetragonal pyramid + plane.) There are 47 simple forms in total. All of them are divided into categories:

Monohedron is a simple shape represented by one face.

Pinacoid - two equal parallel faces that can be reversed.

Dihedron - two equal intersecting faces (can intersect on their continuation).

Rhombic prism - four equal pairs of parallel faces; in cross-section they form a rhombus.

A rhombic pyramid has four equal intersecting sides; in cross-section they also form a rhombus. The listed simple forms are open, since they do not close the space. The presence in a crystal of open simple forms, for example, a rhombic prism, necessarily causes the presence of other simple forms, for example, a pinacoid or a rhombic bipyramid, necessary to obtain a closed form.

Of the closed simple forms of lower systems, we note the following. Rhombic dipyramid: two rhombic pyramids joined at their bases; the shape has eight different faces, giving a rhombus in cross section; A rhombic tetrahedron has four faces that enclose the space and have the shape of oblique triangles.

Middle category(systems: triclinic, tetragonal, hexagonal) – 27 p.f.: monohedron, pinocoid, 6 dipyramids, 6 pyramids, 6 prisms, tetrahedron, rhombohedron, 3 trapezohedrons (trapezoid-shaped faces), 2 scalenoids (formed by doubling the faces of a tetrahedron and rhombohedron).

Highest category– 15 p.f.: the main ones are tetrahedron, octahedron, cube. If instead of one face there are 3 faces - a tritetrahedron, if 6 - a hexatetrahedron, if 4 - a tetratetrahedron. The faces can be 3x, 4x, 5x: 3x - trigon, 4x - tetragon, 5x - pentagon.

A simple crystal form is a family of faces interconnected by symmetric operations of a given symmetry class. All faces that form one simple crystal shape must be equal in size and shape. A crystal may contain one or more simple forms. The combination of several simple forms is called a combination.

Closed forms are those whose edges completely enclose the space enclosed between them, such as a cube;

Open simple forms do not enclose space and cannot exist independently, but only in combinations. For example, prism + pinacoid.

Fig.6. Simple forms of the lowest category: monohedron (1), pinacoid (2), dihedron (3).

In lower syngonies the following open simple forms are possible (Fig. 6):

Monohedron (from the Greek “mono” - one, “hedron” - face) - a simple shape represented by one single face. A monohedron is, for example, the base of a pyramid.

 Pinacoid (from the Greek “pinax” - board) is a simple shape consisting of two equal parallel faces, often reversely oriented.

Dihedron (from the Greek "di" - two, "hedron" - face) - a simple shape formed by two equal intersecting (sometimes on their continuation) edges, forming a "straight roof".

Rhombic prism is a simple shape that consists of four equal, pairwise parallel faces, which in cross-section form a rhombus.

Rhombic pyramid - a simple shape consisting of four equal intersecting faces; in cross-section it is also a rhombus. Of the closed simple forms of lower systems, we note the following:

Rhombic dipyramid: two rhombic pyramids joined at their bases. The shape has eight equal faces, giving a rhombus in cross section.

The rhombic tetrahedron is a simple shape, the four faces of which are shaped like oblique triangles and enclose the space.

Open simple forms of crystal systems of the middle category will be prisms and pyramids.

 Trigonal prism (from the Greek "gon" - angle) - three equal faces intersecting along parallel edges and forming an equilateral triangle in cross-section;

 Tetragonal prism (from the Greek “tetra” - four) - four equal pairs of parallel faces, forming a square in cross-section;

Hexagonal prism (from the Greek "hexa" - six) - six equal faces intersecting along parallel edges and forming a regular hexagon in cross-section.

The names ditrigonal, ditetragonal and dihexagonal are given to prisms with double the number of faces, when all the faces are equal, and the same angles between the faces alternate every other.

Pyramids - simple forms of crystals of the middle category can be, like prisms, trigonal (and ditrigonal), tetragonal (and ditetragonal), hexagonal (and dihexagonal). They form regular polygons in cross-section. The faces of the pyramids are located at an oblique angle to the higher order symmetry axis.

In crystals of the middle category, closed simple forms are also found. There are several such forms:

Dipyramids are simple shapes formed by two equal pyramids joined at their bases. In such forms, the pyramid is doubled by a horizontal plane of symmetry perpendicular to the main axis of symmetry of a higher order (Fig. 8). Dipyramids, like simple pyramids, can have different cross-sectional shapes depending on the order of the axis. They can be trigonal, ditrigonal, tetragonal, ditetragonal, hexagonal and dihexagonal.

Rhombohedron is a simple shape that consists of six diamond-shaped faces and resembles an elongated or diagonally flattened cube. It is only possible in the trigonal system. The upper and lower groups of faces are rotated relative to each other at an angle of 60° so that the lower faces are located symmetrically between the upper ones.

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Lesson type: Combined.

The purpose of the lesson: To create conditions for the development of students’ ability to establish the cause-and-effect dependence of the physical properties of substances on the type of chemical bond and the type of crystal lattice, to predict the type of crystal lattice based on the physical properties of the substance.

Lesson objectives:

To form concepts about the crystalline and amorphous state of solids, to familiarize students with various types of crystal lattices, to establish the dependence of the physical properties of a crystal on the nature of the chemical bond in the crystal and the type of crystal lattice, to give students basic ideas about the influence of the nature of chemical bonds and types of crystal lattices on the properties of matter .
Continue to form the worldview of students, consider mutual influence components of whole-structural particles of substances, as a result of which new properties appear, to develop the ability to organize one’s educational work, and to observe the rules of working in a team.
To develop the cognitive interest of schoolchildren using problem situations;

Equipment: Periodic system D.I. Mendeleev, collection “Metals”, non-metals: sulfur, graphite, red phosphorus, crystalline silicon, iodine; Presentation “Types of crystal lattices”, models of crystal lattices different types(table salt, diamond and graphite, carbon dioxide and iodine, metals), samples of plastics and products made from them, glass, plasticine, computer, projector.

During the classes

1. Organizational moment.

The teacher welcomes students and records those who are absent.

2. Testing knowledge on the topics “Chemical bonding.” Oxidation state.”

Independent work (15 minutes)

3. Studying new material.

The teacher announces the topic of the lesson and the purpose of the lesson. (Slide 1,2)

Students write down the date and topic of the lesson in their notebooks.

Updating knowledge.

The teacher asks questions to the class:

What types of particles do you know? Do ions, atoms and molecules have charges?
What types of chemical bonds do you know?
What aggregative states of substances do you know?

Teacher:“Any substance can be a gas, a liquid or a solid. For example, water. Under normal conditions it is a liquid, but it can be steam and ice. Or oxygen under normal conditions is a gas, at a temperature of -1940 C it turns into liquid blue color, and at a temperature of -218.8°C it hardens into a snow-like mass consisting of crystals of blue color. In this lesson we will look at the solid state of substances: amorphous and crystalline.” (Slide 3)

Teacher: amorphous substances do not have a clear melting point - when heated, they gradually soften and turn into a fluid state. Amorphous substances include, for example, chocolate, which melts in both hands and mouth; chewing gum, plasticine, wax, plastics (examples of such substances are shown). (Slide 7)

Crystalline substances have a clear melting point and, most importantly, are characterized by the correct arrangement of particles at strictly defined points in space. (Slides 5,6) When these points are connected with straight lines, a spatial framework is formed, called a crystal lattice. The points at which crystal particles are located are called lattice nodes.

Students write down the definition in their notebooks: “A crystal lattice is a collection of points in space in which the particles that form a crystal are located. The points at which crystal particles are located are called lattice nodes.”

Depending on what types of particles are located at the nodes of this lattice, there are 4 types of lattices. (Slide 8) If there are ions at the nodes of a crystal lattice, then such a lattice is called ionic.

The teacher asks students questions:

– What will be the name of crystal lattices, in the nodes of which there are atoms and molecules?

But there are crystal lattices, at the nodes of which there are both atoms and ions. Such gratings are called metal gratings.

Now we will fill out the table: “Crystal lattices, type of bond and properties of substances.” As we fill out the table, we will establish the relationship between the type of lattice, the type of connection between particles and the physical properties of solids.

Let's consider the 1st type of crystal lattice, which is called ionic. (Slide 9)

– What is the chemical bond in these substances?

Look at the ionic crystal lattice (a model of such a lattice is shown). Its nodes contain positively and negatively charged ions. For example, a sodium chloride crystal is made up of positive sodium ions and negative chloride ions, forming a cube-shaped lattice. Substances with ionic crystal lattice include salts, oxides and hydroxides of typical metals. Substances with an ionic crystal lattice have high hardness and strength, they are refractory and non-volatile.

Teacher: The physical properties of substances with an atomic crystal lattice are the same as those of substances with an ionic crystal lattice, but often in superlatives– very hard, very durable. Diamond, which has an atomic crystal lattice, is the hardest substance of all natural substances. It serves as a standard of hardness, which, according to a 10-point system, is rated with the highest score of 10. (Slide 10). For this type of crystal lattice, you yourself will enter the necessary information into the table by working with the textbook yourself.

Teacher: Let's consider the 3rd type of crystal lattice, which is called metallic. (Slides 11,12) At the nodes of such a lattice there are atoms and ions, between which electrons move freely, connecting them into a single whole.

This internal structure metals and determines their characteristic physical properties.

Teacher: What physical properties of metals do you know? (malleability, plasticity, electrical and thermal conductivity, metallic luster).

Teacher: What groups are all substances divided into according to their structure? (Slide 12)

Let's consider the type of crystal lattice possessed by such well-known substances as water, carbon dioxide, oxygen, nitrogen and others. It's called molecular. (Slide14)

– What particles are located at the nodes of this lattice?

The chemical bond in molecules that are located at lattice sites can be either polar covalent or nonpolar covalent. Despite the fact that the atoms inside the molecule are connected by very strong covalent bonds, between the molecules themselves there are weak forces intermolecular attraction. Therefore, substances with a molecular crystal lattice have low hardness, low melting points and are volatile. When gaseous or liquid substances special conditions turn into solids, then they have a molecular crystal lattice. Examples of such substances can be solid water - ice, solid carbon dioxide - dry ice. This lattice has naphthalene, which is used to protect woolen products from moths.

– What properties of the molecular crystal lattice determine the use of naphthalene? (volatility). As we see, not only solids can have a molecular crystal lattice. simple substances: noble gases, H 2 , O 2 , N 2 , I 2 , O 3 , white phosphorus P 4, but and complex: solid water, solid hydrogen chloride and hydrogen sulfide. Most solid organic compounds have molecular crystal lattices (naphthalene, glucose, sugar).

The lattice sites contain nonpolar or polar molecules. Despite the fact that the atoms inside the molecules are connected by strong covalent bonds, weak intermolecular forces act between the molecules themselves.

Conclusion: The substances are fragile, have low hardness, low temperature melting, volatile.

Question: Which process is called sublimation or sublimation?

Answer: The transition of a substance from a solid state of aggregation directly to a gaseous state, bypassing the liquid state, is called sublimation or sublimation.

Demonstration of experiment: sublimation of iodine

Then students take turns naming the information they wrote down in the table.

Crystal lattices, type of bond and properties of substances.

Grille type	Types of particles at lattice sites	Type of communication between particles	Examples of substances	Physical properties of substances
Ionic	Ions	Ionic – strong bond	Salts, halides (IA, IIA), oxides and hydroxides of typical metals	Solid, strong, non-volatile, brittle, refractory, many soluble in water, melts conduct electric current
Nuclear	Atoms	1. Covalent non-polar – the bond is very strong 2. Covalent polar – the bond is very strong	*Simple substances* A: diamond (C), graphite (C), boron (B), silicon (Si). *Complex substances* : aluminum oxide (Al 2 O 3), silicon oxide (IV) – SiO 2	Very hard, very refractory, durable, non-volatile, insoluble in water
Molecular	Molecules	There are weak forces between molecules intermolecular attraction, but inside the molecules - strong covalent bond	Solids under special conditions that are gases or liquids under normal conditions (O 2, H 2, Cl 2, N 2, Br 2, H 2 O, CO 2, HCl); sulfur, white phosphorus, iodine; organic matter	Fragile, volatile, fusible, capable of sublimation, have low hardness
Metal	Atom ions	Metal - different strengths	Metals and alloys	Malleable, shiny, ductile, thermally and electrically conductive

Teacher: What conclusion can we draw from the work done on the table?

Conclusion 1: The physical properties of substances depend on the type of crystal lattice. Composition of the substance → Type of chemical bond → Type of crystal lattice → Properties of substances . (Slide 18).

Question: Which type of crystal lattice from those discussed above is not found in simple substances?

Answer: Ionic crystal lattices.

Question: What crystal lattices are characteristic of simple substances?

Answer: For simple substances - metals - a metal crystal lattice; for non-metals – atomic or molecular.

Working with the Periodic System D.I. Mendeleev.

Question: Where are the metal elements located in the Periodic Table and why? Non-metal elements and why?

Answer : If you draw a diagonal from boron to astatine, then in the lower left corner of this diagonal there will be metal elements, because at the last energy level they contain from one to three electrons. These are elements I A, II A, III A (except boron), as well as tin and lead, antimony and all elements of secondary subgroups.

Non-metal elements are located in the upper right corner of this diagonal, because at the last energy level they contain from four to eight electrons. These are the elements IV A, V A, VI A, VII A, VIII A and boron.

Teacher: Let's find non-metal elements whose simple substances have an atomic crystal lattice (Answer: C, B, Si) and molecular ( Answer: N, S, O , halogens and noble gases )

Teacher: Formulate a conclusion on how you can determine the type of crystal lattice of a simple substance depending on the position of the elements in D.I. Mendeleev’s Periodic Table.

Answer: For metal elements that are in I A, II A, IIIA (except boron), as well as tin and lead, and all elements of secondary subgroups in a simple substance, the type of lattice is metal.

For non-metal elements IV A and boron in a simple substance, the crystal lattice is atomic; and the elements V A, VI A, VII A, VIII A in simple substances have a molecular crystal lattice.

We continue to work with the completed table.

Teacher: Look carefully at the table. What pattern can be observed?

We listen carefully to the students’ answers, and then together with the class we draw a conclusion. Conclusion 2 (slide 17)

4. Fixing the material.

Test (self-control):

Substances that have a molecular crystal lattice, as a rule:
a) Refractory and highly soluble in water
b) Fusible and volatile
c) Solid and electrically conductive
d) Thermally conductive and plastic

The concept of “molecule” is not applicable to the structural unit of a substance:
a) Water
b) Oxygen
c) Diamond
d) Ozone

The atomic crystal lattice is characteristic of:
a) Aluminum and graphite
b) Sulfur and iodine
c) Silicon oxide and sodium chloride
d) Diamond and boron

If a substance is highly soluble in water, it has high temperature melting, electrically conductive, then its crystal lattice:
a) Molecular
b) Nuclear
c) Ionic
d) Metal

5. Reflection.

6. Homework.

Characterize 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 → Interaction forces between the particles of the crystal → Physical properties due to the crystal lattice → Aggregate state of the substance under normal conditions → Examples.

Using 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 expected physical properties of each of the four substances.

Diagnostics and diseases. Medicines from A to Z

Substances have a molecular crystal lattice. Crystal lattices – Knowledge Hypermarket

Crystals

Ionic crystal lattices

Atomic crystal lattices

Molecular crystals

Metal crystal lattices

2. Properties of crystalline substances - homogeneity, anisotropy, ability to self-cut.

3. The concept of syngony. What categories are syngonies divided into?

4.Simple shapes and combinations. The physical meaning of isolating simple forms in a crystal.

During the classes

1. Organizational moment.

2. Testing knowledge on the topics “Chemical bonding.” Oxidation state.”

3. Studying new material.

4. Fixing the material.

5. Reflection.

6. Homework.