Carbon type of crystal lattice is ionic. Types of crystal lattices of various substances

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 the molecules of which 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.

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.

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.

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.

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.

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 the solid state 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.

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.

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. Center. Option 1.

For substances with a molecular crystal lattice 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: USE 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, as a rule, solid and refractory substances.

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

Answer: 1

Source: USE 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, as a rule, solid and refractory substances.

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.

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 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?

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

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.

Types of crystal lattices

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

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

Crystal cell - this is 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 (that is, 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 attributed to 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 a 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

	ionic			metallic
What is in the nodes of the crystal lattice, structural unit	ions	atoms	molecules	atoms and cations
Type of chemical bond between knot particles	ionic		covalent: polar and non-polar	metallic
Forces of interaction between crystal particles	electrostatic cal	covalent	intermolecular nye	electrostatic cal
Physical properties due to the crystal lattice	the attractive forces between the ions are strong, T pl. (refractory), Easily soluble in water melt and solution conducts electric current, non-volatile (no smell)	covalent bonds between atoms are large, T pl. and T kip very, are not soluble in water the melt does not conduct electricity	The attractive forces between molecules are small T pl. ↓, Some dissolve in water They have an odor - they are volatile	interaction forces are great T pl. , High thermal and electrical conductivity
Aggregate state of matter under normal conditions	solid	solid	hard, gaseous, liquid	hard, liquid(H g)
Examples	most salts, alkalis, typical metal oxides	C (diamond, graphite), Si, Ge, B, SiO 2, CaC 2, SiC (carborundum), BN, Fe 3 C, TaC (t pl. \u003d 3800 0 С) Red and black phosphorus. Oxides of some metals.	all gases, liquids, most non-metals: inert gases, halogens, H 2 , N 2 , O 2 , O 3 , P 4 (white), S 8 . Hydrogen compounds of non-metals, oxides of non-metals: H 2 O, CO 2 "dry ice". Majority organic compounds.	Metals, alloys

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

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.

		Group
			III			VII	VIII
P e R and about d						H2
				N 2	O2	F2
	III			P4	S8	Cl2
						Br2
						I 2
Type of crystal lattice		metallic			nuclear	molecular

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:

What is a crystal lattice?
What types of crystal lattices exist?
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:

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), table salt? Make a generalized conclusion: what properties of a substance can determine the type of its crystal lattice?
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.
Trainer number 1. "Crystal Grids"
Trainer number 2. "Test tasks"
Test (self-control):

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

a). refractory and highly soluble in water
b). fusible and volatile
in). Solid and electrically conductive
G). Thermally conductive and plastic

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

Back forward

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Lesson type: Combined.

The purpose of the lesson: To create conditions for the formation of students' ability to establish a causal dependence of the physical properties of substances on the type of chemical bond and type of crystal lattice, to predict the type of crystal lattice based on the physical properties of a substance.

Lesson objectives:

To form the concepts of crystalline and amorphous state solids introduce students to the different types crystal lattices, 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, give students basic ideas about the influence of the nature of the chemical bond and types of crystal lattices on the properties of a substance.
To continue the formation of students' worldview, to consider the mutual influence of the components of the whole-structural particles of substances, as a result of which new properties appear, to cultivate the ability to organize their educational work, to follow the rules of working in a team.
Develop cognitive interest schoolchildren, using problem situations;

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

During the classes

1. Organizational moment.

The teacher greets the students, fixes the absent ones.

2. Checking knowledge on topics” Chemical bond. The degree of oxidation”.

Independent work (15 minutes)

3. Learning new material.

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

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

Knowledge update.

The teacher asks the class questions:

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

Teacher:“Any substance can be gas, liquid and 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 a 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 consider 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 become fluid. Amorphous substances include, for example, chocolate, which melts both in the hands and in the 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 correct location particles at strictly defined points in space. (Slides 5,6) When these points are connected by straight lines, a spatial frame is formed, called a crystal lattice. The points at which crystal particles are located are called lattice nodes.

Students write down the definition in a notebook: “A crystal lattice is a set of points in space in which the particles that form a crystal are located. The points where the particles of the crystal are located are called the nodes of the lattice.

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

The teacher asks students questions:

- What will be called crystal lattices, in the nodes of which there are atoms, molecules?

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

Now we will fill in the table: "Crystal lattices, type of bond and properties of substances." In the course of filling in the table, we will establish the relationship between the type of lattice, the type of connection between particles and the physical properties of solids.

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). At its nodes are positively and negatively charged ions. For example, a sodium chloride crystal is made up of positive sodium ions and negative chloride ions in a cube-shaped lattice. Substances with an 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, in which the 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). According to this type of crystal lattice, you yourself will make necessary information in the table, having independently worked with the textbook.

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

Such an internal structure of metals determines their characteristic physical properties.

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

Teacher: What groups are all substances divided into by structure? (Slide 12)

Consider the type of crystal lattice, which is possessed by such well-known substances as water, carbon dioxide, oxygen, nitrogen and others. It's called molecular. (Slide 14)

What particles are located at the nodes of this lattice?

The chemical bond in the molecules that are at the lattice sites can be both covalent polar and covalent non-polar. Despite the fact that the atoms within the molecule are bound by very strong covalent bonds, weak forces of intermolecular attraction act between the molecules themselves. Therefore, substances with a molecular crystal lattice have low hardness, low melting points and are volatile. When gaseous or liquid substances turn into solids under special conditions, then they have a molecular crystal lattice. Examples of such substances can be solid water - ice, solid carbon dioxide - dry ice. Such a 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 you can see, the molecular crystal lattice can have not only solid simple substances: noble gases, H 2, O 2, N 2, I 2, O 3, white phosphorus R 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 non-polar or polar molecules. Despite the fact that the atoms inside the molecules are bound by strong covalent bonds, weak forces of intermolecular interaction act between the molecules themselves.

Conclusion: Substances are fragile, have low hardness, low temperature melting, flying.

Question: What process is called sublimation or sublimation?

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

Demonstration of experience: iodine sublimation

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

Crystal lattices, type of bond and properties of substances.

Lattice type	Types of particles at lattice sites	Communication type between particles	Substance examples	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 electricity
Atomic	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, strong, non-volatile, insoluble in water
Molecular	molecules	Between molecules - weak forces intermolecular attraction, but inside molecules - a strong covalent bond	Solids under special conditions, which under ordinary conditions are gases or liquids (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 a small hardness
metal	atom ions	Metal - different strength	Metals and alloys	Malleable, have gloss, ductility, heat and electrical conduction

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

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

Question: Which type of crystal lattice of the above is not found in simple substances?

Answer: Ionic crystal lattices.

Question: What crystal lattices are typical for simple substances?

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

Work with the Periodic system of D.I. Mendeleev.

Question: Where in Periodic system are metal elements and why? Elements are non-metals and why?

Answer : If we draw a diagonal from boron to astatine, then in the lower left corner from 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 for 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 contain from four to eight electrons. These are elements IV A, V A, VI A, VII A, VIII A and boron.

Teacher: Let's find the non-metal elements that have 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 the Periodic system of D.I. Mendeleev.

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 lattice type is metallic.

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 closely at the table. What pattern is observed?

We carefully listen to the answers of the students, after which we draw a conclusion together with the class. 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 in relation to the structural unit of a substance:
a) Water
b) Oxygen
c) Diamond
d) Ozone

The atomic crystal lattice is characteristic for:
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, has a high melting point, and is electrically conductive, then its crystal lattice:
a) Molecular
b) Nuclear
c) Ionic
d) metal

5. Reflection.

6. Homework.

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 the particles of the crystal → Physical properties due to the crystal lattice → Aggregate state of matter under normal conditions → Examples.

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 expected physical properties of each of the four substances.

During the implementation of many physical and chemical reactions the substance passes into a solid state of aggregation. At the same time, molecules and atoms tend to arrange themselves in such a spatial order in which the interaction forces between the particles of the substance would be maximally balanced. This is how the strength of the solid is achieved. Atoms, once having taken a certain position, make small oscillatory movements, the amplitude of which depends on temperature, but their position in space remains fixed. The forces of attraction and repulsion balance each other over a certain distance.

Modern ideas about the structure of matter

Modern science claims that an atom consists of a charged nucleus, which carries a positive charge, and electrons, which carry negative charges. At a speed of several thousand trillion revolutions per second, electrons rotate in their orbits, creating an electron cloud around the nucleus. The positive charge of the nucleus is numerically equal to negative charge electrons. Thus, the atom of the substance remains electrically neutral. Possible interactions with other atoms occur when electrons are detached from the native atom, thereby disturbing the electrical balance. In one case, the atoms line up in a certain order, which is called the crystal lattice. In the other, due to the complex interaction of nuclei and electrons, they combine into molecules different kind and complexity.

Determination of the crystal lattice

Taken together, various types of crystal lattices of substances are grids with different spatial orientations, at the nodes of which ions, molecules or atoms are located. This stable geometric spatial position is called the crystal lattice of a substance. The distance between the nodes of one crystal cell is called the identity period. The spatial angles at which the nodes of the cell are located are called parameters. According to the method of building bonds, crystal lattices can be simple, base-centered, face-centered and body-centered. If the particles of matter are located only in the corners of the parallelepiped, such a lattice is called simple. An example of such a lattice is shown below:

If, in addition to nodes, the particles of a substance are also located in the middle of the spatial diagonals, then such a construction of particles in a substance is called a body-centered crystal lattice. The figure shows this type clearly.

If, in addition to nodes at the vertices of the lattice, there is a node at the place where the imaginary diagonals of the parallelepiped intersect, then you have a face-centered type of lattice.

Types of crystal lattices

Different microparticles that make up a substance determine different types of crystal lattices. They can determine the principle of building a bond between microparticles inside a crystal. Physical types of crystal lattices - ionic, atomic and molecular. This also includes various types of crystal lattices of metals. By learning the principles internal structure elements deals with chemistry. The types of crystal lattices are detailed below.

Ionic crystal lattices

These types of crystal lattices are present in compounds with an ionic type of bond. In this case, the lattice sites contain ions with opposite electric charges. Thanks to electromagnetic field, the forces of interionic interaction turn out to be quite strong, and this determines the physical properties of the substance. The usual characteristics are refractoriness, density, hardness and the ability to conduct electric current. Ionic types of crystal lattices are found in substances such as table salt, potassium nitrate and others.

Atomic crystal lattices

This type of structure of a substance is inherent in elements whose structure is determined by a covalent chemical bond. Types of crystal lattices of this kind contain individual atoms at the nodes, interconnected by strong covalent bonds. A similar type of bond occurs when two identical atoms "share" electrons, thereby forming a common pair of electrons for neighboring atoms. Due to this interaction, covalent bonds evenly and strongly bind atoms in a certain order. Chemical elements that contain atomic types crystal lattices, have hardness, high melting point, poorly conduct electric current and are chemically inactive. Diamond, silicon, germanium, and boron are classic examples of elements with a similar internal structure.

Molecular crystal lattices

Substances having a molecular type of crystal lattice are a system of stable, interacting, closely packed molecules that are located at the nodes of the crystal lattice. In such compounds, the molecules retain their spatial position in the gaseous, liquid and solid phases. Molecules are held at the sites of the crystal by weak van der Waals forces, which are ten times weaker than the forces of ionic interaction.

The molecules forming the crystal can be either polar or non-polar. Due to the spontaneous movement of electrons and vibrations of nuclei in molecules, the electrical equilibrium can shift - this is how an instantaneous electric moment of the dipole arises. Appropriately oriented dipoles create attractive forces in the lattice. Carbon dioxide and paraffin are typical examples of elements with a molecular crystal lattice.

Metallic crystal lattices

A metallic bond is more flexible and plastic than an ionic one, although it may seem that both of them are based on the same principle. The types of crystal lattices of metals explain their typical properties - such as, for example, mechanical strength, thermal and electrical conductivity, fusibility.

A distinctive feature of the metal crystal lattice is the presence of positively charged metal ions (cations) at the nodes of this lattice. Between the nodes are electrons that are directly involved in the creation electric field around the grid. The number of electrons moving within this crystal lattice is called the electron gas.

In the absence of an electric field, free electrons make chaotic movement, randomly interacting with lattice ions. Each such interaction changes the momentum and direction of motion of a negatively charged particle. With their electric field, electrons attract cations to themselves, balancing their mutual repulsion. Although electrons are considered free, their energy is not enough to leave the crystal lattice, so these charged particles are constantly within it.

The presence of an electric field gives the electron gas additional energy. The connection with ions in the crystal lattice of metals is not strong, so the electrons easily leave its limits. Electrons move along lines of force leaving positively charged ions behind.

conclusions

Chemistry pays great attention to the study of the internal structure of matter. Types of crystal lattices various elements determine almost the entire range of their properties. By influencing crystals and changing their internal structure, it is possible to enhance the desired properties of a substance and remove unwanted ones, transform chemical elements. Thus, the study of the internal structure of the surrounding world can help to understand the essence and principles of the structure of the universe.

As we already know, matter can exist in three states of aggregation: gaseous, solid and liquid. Oxygen, which under normal conditions is in a gaseous state, at a temperature of -194 ° C is converted into a bluish liquid, and at a temperature of -218.8 ° C it turns into a snowy mass with blue crystals.

The temperature interval for the existence of a substance in the solid state is determined by the boiling and melting points. Solids are crystalline and amorphous.

At amorphous substances there is no fixed melting point - when heated, they gradually soften and become fluid. In this state, for example, there are various resins, plasticine.

Crystalline substances differ in the regular arrangement of the particles of which they are composed: atoms, molecules and ions, at strictly defined points in space. When these points are connected by straight lines, a spatial frame is created, it is called a crystal lattice. The points where the crystal particles are located are called lattice nodes.

At the nodes of the lattice we imagine, there can be ions, atoms and molecules. These particles oscillate. When the temperature increases, the scope of these fluctuations also increases, which leads to thermal expansion of the bodies.

Depending on the type of particles located in 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 metal.

Ionic called such crystal lattices, at the nodes of which ions are located. They are formed by substances with an ionic bond, which can be associated with both simple ions Na +, Cl-, and complex SO24-, OH-. Thus, ionic crystal lattices have salts, some oxides and hydroxyls of metals, i.e. those substances in which there is an ionic chemical bond. Let's consider a crystal of sodium chloride, it consists of positively alternating Na+ and negative CL- ions, together they form a lattice in the form of a cube. The bonds between ions in such a crystal are extremely stable. Because of this, substances with an ionic lattice have a relatively high strength and hardness, they are refractory and non-volatile.

nuclear crystal lattices are called such crystal lattices, at the nodes of which there are individual atoms. In such lattices, atoms are interconnected by very strong covalent bonds. For example, diamond is one of the allotropic modifications of carbon.

Substances with an atomic crystal lattice are not very common in nature. These include crystalline boron, silicon and germanium, as well as complex substances, for example, those that contain silicon oxide (IV) - SiO 2: silica, quartz, sand, rock crystal.

The vast majority of substances with an atomic crystal lattice have very high temperatures melting (for diamond it exceeds 3500 ° C), such substances are strong and hard, practically insoluble.

Molecular called such crystal lattices, at the nodes of which molecules are located. Chemical bonds in these molecules can also be either polar (HCl, H 2 0) or non-polar (N 2 , O 3). And although the atoms inside the molecules are connected by very strong covalent bonds, weak forces of intermolecular attraction act between the molecules themselves. That is why substances with molecular crystal lattices are characterized by low hardness, low melting point, and volatility.

Examples of such substances are solid water - ice, solid carbon monoxide (IV) - "dry ice", solid hydrogen chloride and hydrogen sulfide, solid simple substances formed by one - (noble gases), two - (H 2, O 2, CL 2 , N 2, I 2), three - (O 3), four - (P 4), eight-atomic (S 8) molecules. The vast majority of solid organic compounds have molecular crystal lattices (naphthalene, glucose, sugar).

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