Basic types of chemical bonds. Chemical bond. Types of chemical bonds Test 3 types of chemical bonds types

Types of chemical wigeons.

Part A

1) Li+ and I - 2) Br- And H + 3) H+ and B 3+ 4) S 2- and O 2-

1) ionic 2) metallic 3) covalent nonpolar 4) covalent polar

1) ionic 2) metallic 3) covalent nonpolar 4) covalent polar

1) ionic 2) metallic 3) covalent nonpolar 4) covalent polar

1) NaCl, KOH 2) HI, H 2 O 3)CO 2 , Br 2 4)CH 4 , F 2

1)1 2)2 3)3 4)4

1) KCl 2) CO 3) H 2 O 4) HCl

Part B

A) iron 1) ionic

D) nitrogen

Part C

Types of chemical wigeons.

Part A

1. Chemical bond in a hydrogen fluoride molecule

1) ionic 2) metallic 3) covalent nonpolar 4) covalent polar

2. ionic bond is formed between atoms

1) sodium and fluorine 2) sulfur and hydrogen 3) sulfur and oxygen 4) chlorine and hydrogen

3. An ionic bond is formed between ions

1) Li+ and I - 2) Br- And H + 3) H+ and B 3+ 4) S 2- and O 2-

4. Chemical bond between atoms of chemical elements with serial numbers 3 and 35

1) ionic 2) metallic 3) covalent nonpolar 4) covalent polar

5. A chemical bond between atoms whose electronegativities do not differ from each other is called

1) ionic 2) metallic 3) covalent nonpolar 4) covalent polar

6. Chemical bond of an atom of a chemical element having six electrons in the outer electron layer with hydrogen

1) ionic 2) metallic 3) covalent nonpolar 4) covalent polar

7. Covalent polar bond in each of two substances:

1) NaCl, KOH 2) HI, H 2 O 3)CO 2 , Br 2 4)CH 4 , F 2

8. There are two common electron pairs in the molecule

1) hydrogen 2) hydrogen bromide 3) hydrogen sulfide 4) ammonia

9. A molecule has one covalent bond

1)hydrogen iodide 2)nitrogen 3)methane 4)oxygen

10. Number of shared electron pairs in EO compounds 2

1)1 2)2 3)3 4)4

11. Give the formula for the extra compound

1) KCl 2) CO 3) H 2 O 4) HCl

Part B

12. Match the name of the compound and the type of chemical bond in this compound.

Name of compound Type of chemical bond

A) iron 1) ionic

B) oxygen 2) covalent polar

B) water 3) covalent non-polar

D) lithium bromide 4) metal

D) nitrogen

13. Covalent polar bonds occur in compounds:

1) hydrogen sulfide 2) carbon monoxide 3) fluorine 4) zinc 5) potassium fluoride 3) fluorine

14. Molecules have three covalent polar bonds

1) nitrogen 2) phosphine 3) carbon dioxide 4) ammonia 5) methane

Part C

15. Give examples of four potassium compounds that have both ionic and covalent bonds.

16. Name a compound that has one covalent nonpolar bond of atoms whose electrons are located on three energy layers.

1. The bond between metal ions and stray electrons is called: IONIC COVALENT NOPOLAR METAL COVALENT POLAR

2. A chemical bond that occurs between atoms of non-metals of the same type is called: IONIC COVALENT NON-POLAR METAL COVALENT POLAR

3. A chemical bond that occurs between non-metal atoms having different electronegativity is called IONIC COVALENT NON-POLAR METAL COVALENT POLAR

4. The chemical bond that occurs between the atoms of a typical metal and a typical non-metal is called: IONIC COVALENT NON-POLAR METAL COVALENT POLAR

5. Select a group of substances that includes only substances with a covalent nonpolar bond: N 2, NH 3, CO 2, NH 3, H 2, KF H 2 O, Na. Cl N 2, H 2, F 2, C Na, H 2, HF, Ca. CO3

6. Select a group of substances that includes only substances with a covalent polar bond: N 2, NH 3, CO 2, Na, NH 3, H 2, KF H 2 O, HCl F 2, HF, C Ca. CO3

7. Select a group of substances that includes only substances with a metallic bond: Na, CO 2, K, Al, NH 3, Fe H 2 O, Na. Cl N 2, H 2, F 2, C Na, H 2, HF, Ca. CO3

8. Select a group of substances that includes only substances with ionic bonds: Na, K, Al, Fe CO 2, Na. Cl, NH 3, H 2, H 2 O, HCl F 2, C KF, Mg. I 2, Ca. Cl2

9. Determine the type of chemical bond and the type of crystal lattice, if the substance has a high melting and boiling point, is solid, refractory, and highly soluble in water. The solution conducts electric current. Covalent polar bond and atomic crystal lattice Ionic bond and ionic crystal lattice Covalent polar bond and molecular crystal lattice. Metal bond and metal crystal lattice. Covalent nonpolar bond and molecular crystal lattice

Study the main types of chemical bonds.

Practice the skill of determining the type of chemical bond.

Learn to create graphic formulas for substances.

Lesson progress: (Slide 3)

Chemical dictation

Checking homework (oral questioning)

1. Explanation of the topic “Basic types of chemical bonds.”
2. Reinforcement (Test)
3. Working in the graphic editor “Paint” – drawing up graphic formulas of substances.
4. Homework.

During the classes

I. Chemical dictation.(Slide 4)

Chemistry Tests Program

“Chemical dictation”

Answer 10 questions in 2 minutes

II. Checking homework

(Slide 5)

(Oral survey)

1. What is electronegativity?
2. Dependence of electronegativity on the location of an element in the periodic table?
3. How to determine whether an element is a metal or non-metal by electronegativity?

III. Explanation of the topic “Basic types of chemical bonds.” (

Slide 6)

• The bond between elements with the same or similar electronegativity is called covalent. (Slide 7)
• The bond between metals is called metallic.
• The bond between elements with significantly different electronegativity is called ionic.
• The bond between electronegative elements of different molecules using hydrogen is called hydrogen bonding. .

IV. Consolidation (Test)

(Slide 19)

Chemistry Tests program.

Choose:

“Reinforcement 3” – for those who are not entirely confident in their knowledge,
“Reinforcement 4” – for those who are confident in their knowledge,
“Reinforcement 5” is for those who are absolutely confident in their knowledge.

1. Answer questions.
2. You receive a grade and wait until the teacher allows you to close the program.

V. Work in the graphic editor “Paint” - drawing up graphic formulas of substances.

(Slide 9)

1.Open the “Paint” program.
2. Using “tool kits,” create graphic formulas for substances: water, sodium fluoride, hydrogen chloride, methane.
H 2 O, NaF, HCl, CH 4.

A covalent bond is the most common type of chemical bond, arising due to the sharing of an electron pair through an exchange mechanism, when each of the interacting atoms supplies one electron, or through a donor-acceptor mechanism, if an electron pair is shared by one atom (donor) to another atom (acceptor) (Fig. 3.2).

A classic example of a nonpolar covalent bond (the electronegativity difference is zero) is observed in homonuclear molecules: H–H, F–F. The energy of a two-electron two-center bond lies in the range of 200–2000 kJ∙mol –1.

When a heteroatomic covalent bond is formed, an electron pair is shifted to a more electronegative atom, which makes the bond polar. (HCl, H2O). The ionicity of a polar bond as a percentage is calculated by the empirical relation 16(χ A – χ B) + 3.5(χ A – χ B) 2, where χ A and χ B are the electronegativity of atoms A and B of the AB molecule. In addition to polarizability, a covalent bond has the property of saturation - the ability of an atom to form as many covalent bonds as it has energetically accessible atomic orbitals. The third property of a covalent bond - directionality - will be discussed below (see the method of valence bonds).

An ionic bond is a special case of a covalent bond, when the resulting electron pair completely belongs to a more electronegative atom, which becomes an anion. The basis for identifying this bond as a separate type is the fact that compounds with such a bond can be described in an electrostatic approximation, considering the ionic bond to be due to the attraction of positive and negative ions. The interaction of ions of the opposite sign does not depend on the direction, and Coulomb forces do not have the property of saturation. Therefore, each ion in an ionic compound attracts such a number of ions of the opposite sign that a crystal lattice of an ionic type is formed. There are no molecules in an ionic crystal. Each ion is surrounded by a certain number of ions of a different sign (the coordination number of the ion). Ion pairs can exist in the gaseous state as polar molecules. In the gaseous state, NaCl has a dipole moment of ~3∙10 –29 C∙m, which corresponds to a displacement of 0.8 electron charge per bond length of 0.236 nm from Na to Cl, i.e. Na 0.8+Cl 0.8–.

The metallic bond arises as a result of partial delocalization of valence electrons, which move quite freely in the metal lattice, electrostatically interacting with positively charged ions. The binding forces are not localized or directed, and delocalized electrons cause high thermal and electrical conductivity.

Hydrogen bond. Its formation is due to the fact that, as a result of a strong displacement of an electron pair towards an electronegative atom, a hydrogen atom, which has an effective positive charge, can interact with another electronegative atom (F, O, N, less often Cl, Br, S). The energy of such electrostatic interaction is 20–100 kJ∙mol –1. Hydrogen bonds can be intra- and intermolecular. An intramolecular hydrogen bond is formed, for example, in acetylacetone and is accompanied by ring closure (Fig. 3.3).

Carboxylic acid molecules in non-polar solvents dimerize due to two intermolecular hydrogen bonds (Fig. 3.4).

Hydrogen bonds play an extremely important role in biological macromolecules, such inorganic compounds as H 2O, H 2F 2, NH 3. Due to hydrogen bonds, water is characterized by such high melting and boiling points compared to H 2E (E = S, Se, Te) . If there were no hydrogen bonds, then water would melt at –100 °C and boil at –80 °C.

Van der Waals (intermolecular) bonding is the most universal type of intermolecular bonding, caused by dispersion forces (induced dipole - induced dipole), inductive interaction (permanent dipole - induced dipole) and orientational interaction (permanent dipole - permanent dipole). The energy of the van der Waals bond is less than the hydrogen bond and amounts to 2–20 kJ∙mol –1.

Chemical bonding in solids. The properties of solids are determined by the nature of the particles occupying the sites of the crystal lattice and the type of interaction between them.

Solid argon and methane form atomic and molecular crystals, respectively. Since the forces between atoms and molecules in these lattices are of the weak van der Waals type, such substances melt at fairly low temperatures. Most substances that are in liquid and gaseous states at room temperature form molecular crystals at low temperatures.

The melting points of ionic crystals are higher than those of atomic and molecular crystals because the electrostatic forces acting between ions far exceed the weak van der Waals forces. Ionic compounds are harder and more brittle. Such crystals are formed by elements with widely different electronegativities (for example, alkali metal halides). Ionic crystals containing polyatomic ions have lower melting points; so for NaCl t pl. = 801 °C, and for NaNO 3 t pl = 311 °C.

In covalent crystals, the lattice is built from atoms connected by a covalent bond, so these crystals have high hardness, melting point and low thermal and electrical conductivity.

Crystal lattices formed by metals are called metallic. The sites of such lattices contain positive metal ions, and the interstices contain valence electrons (electron gas).

Among the metals, d-elements have the highest melting point, which is explained by the presence in the crystals of these elements of a covalent bond formed by unpaired d-electrons, in addition to the metallic bond formed by s-electrons.