3 in a fluorine molecule is a chemical bond. The least strong chemical bond in the fluorine molecule. Chemical bond. Physical properties of fluorine
Task number 1
From the proposed list, select two compounds in which there is an ionic chemical bond.
- 1. Ca(ClO 2) 2
- 2. HClO 3
- 3.NH4Cl
- 4. HClO 4
- 5.Cl2O7
Answer: 13
In the vast majority of cases, the presence of an ionic type of bond in a compound can be determined by the fact that its structural units simultaneously include atoms of a typical metal and non-metal atoms.
On this basis, we establish that there is an ionic bond in compound number 1 - Ca(ClO 2) 2, because in its formula, one can see atoms of a typical calcium metal and atoms of non-metals - oxygen and chlorine.
However, there are no more compounds containing both metal and non-metal atoms in this list.
Among the compounds indicated in the assignment there is ammonium chloride, in which the ionic bond is realized between the ammonium cation NH 4 + and the chloride ion Cl − .
Task number 2
From the proposed list, select two compounds in which the type of chemical bond is the same as in the fluorine molecule.
1) oxygen
2) nitric oxide (II)
3) hydrogen bromide
4) sodium iodide
Write down the numbers of the selected connections in the answer field.
Answer: 15
The fluorine molecule (F 2) consists of two atoms of one non-metal chemical element, therefore the chemical bond in this molecule is covalent non-polar.
A covalent non-polar bond can only be realized between atoms of the same chemical element of a non-metal.
Of the proposed options, only oxygen and diamond have a covalent non-polar type of bond. The oxygen molecule is diatomic, consists of atoms of one chemical element of a non-metal. Diamond has an atomic structure and in its structure each carbon atom, which is a non-metal, is bonded to 4 other carbon atoms.
Nitric oxide (II) is a substance consisting of molecules formed by atoms of two different non-metals. Since the electronegativity of different atoms is always different, the common electron pair in the molecule is shifted towards the more electronegative element, in this case to oxygen. Thus, the bond in the NO molecule is covalent polar.
Hydrogen bromide also consists of diatomic molecules made up of hydrogen and bromine atoms. The shared electron pair forming the H-Br bond is shifted to the more electronegative bromine atom. The chemical bond in the HBr molecule is also covalent polar.
Sodium iodide is an ionic substance formed by a metal cation and an iodide anion. The bond in the NaI molecule is formed due to the transfer of an electron from 3 s-orbitals of the sodium atom (the sodium atom turns into a cation) to an underfilled 5 p-orbital of the iodine atom (the iodine atom turns into an anion). Such a chemical bond is called ionic.
Task number 3
From the proposed list, select two substances between the molecules of which hydrogen bonds are formed.
- 1. C 2 H 6
- 2.C2H5OH
- 3.H2O
- 4. CH 3 OCH 3
- 5. CH 3 COCH 3
Write down the numbers of the selected connections in the answer field.
Answer: 23
Explanation:
Hydrogen bonds take place in substances of a molecular structure, in which there are covalent bonds H-O, H-N, H-F. Those. covalent bonds of the hydrogen atom with the atoms of the three chemical elements with the highest electronegativity.
Thus, obviously, there are hydrogen bonds between molecules:
2) alcohols
3) phenols
4) carboxylic acids
5) ammonia
6) primary and secondary amines
7) hydrofluoric acid
Task number 4
From the proposed list, select two compounds with an ionic chemical bond.
- 1. PCl 3
- 2.CO2
- 3.NaCl
- 4. H 2 S
- 5. MgO
Write down the numbers of the selected connections in the answer field.
Answer: 35
Explanation:
In the overwhelming majority of cases, it can be concluded that there is an ionic type of bond in a compound by the fact that the composition of the structural units of a substance simultaneously includes atoms of a typical metal and non-metal atoms.
On this basis, we establish that there is an ionic bond in compound number 3 (NaCl) and 5 (MgO).
Note*
In addition to the above feature, the presence of an ionic bond in a compound can be said if its structural unit contains an ammonium cation (NH 4 +) or its organic analogs - cations of alkylammonium RNH 3 + , dialkylammonium R 2 NH 2 + , trialkylammonium R 3 NH + or tetraalkylammonium R 4 N + , where R is some hydrocarbon radical. For example, the ionic type of bond takes place in the compound (CH 3) 4 NCl between the cation (CH 3) 4 + and the chloride ion Cl - .
Task number 5
From the proposed list, select two substances with the same type of structure.
4) table salt
Write down the numbers of the selected connections in the answer field.
Answer: 23
Task number 8
From the proposed list, select two substances of non-molecular structure.
2) oxygen
3) white phosphorus
5) silicon
Write down the numbers of the selected connections in the answer field.
Answer: 45
Task number 11
From the proposed list, select two substances in the molecules of which there is a double bond between carbon and oxygen atoms.
3) formaldehyde
4) acetic acid
5) glycerin
Write down the numbers of the selected connections in the answer field.
Answer: 34
Task number 14
From the proposed list, select two substances with an ionic bond.
1) oxygen
3) carbon monoxide (IV)
4) sodium chloride
5) calcium oxide
Write down the numbers of the selected connections in the answer field.
Answer: 45
Task number 15
From the proposed list, select two substances with the same type of crystal lattice as diamond.
1) silica SiO 2
2) sodium oxide Na 2 O
3) carbon monoxide CO
4) white phosphorus P 4
5) silicon Si
Write down the numbers of the selected connections in the answer field.
Answer: 15
Task number 20
From the proposed list, select two substances in the molecules of which there is one triple bond.
- 1. HCOOH
- 2.HCOH
- 3. C 2 H 4
- 4. N 2
- 5.C2H2
Write down the numbers of the selected connections in the answer field.
Answer: 45
Explanation:
In order to find the correct answer, let's draw the structural formulas of the compounds from the list presented:
Thus, we see that the triple bond exists in the molecules of nitrogen and acetylene. Those. correct answers 45
Task number 21
From the proposed list, select two substances in the molecules of which there is a covalent non-polar bond.
Chemistry preparation for ZNO and DPA
Comprehensive edition
PART AND
GENERAL CHEMISTRY
CHEMISTRY OF THE ELEMENTS
HALOGENS
Simple substances
Chemical properties of Fluorine
Fluorine is the strongest oxidizing agent in nature. Directly it does not react only with helium, neon and argon.
During the reaction with metals, fluorides are formed, ionic type compounds:
Fluorine reacts vigorously with many non-metals, even with some inert gases:
Chemical properties of chlorine. Interaction with complex substances
Chlorine is a stronger oxidizing agent than bromine or iodine, so chlorine displaces heavy halogens from their salts:
Dissolving in water, chlorine partially reacts with it, resulting in the formation of two acids: chloride and hypochlorite. In this case, one chlorine atom increases the degree of oxidation, and the other atom reduces it. Such reactions are called disproportionation reactions. Disproportionation reactions are self-healing-self-oxidation reactions, i.e. reactions in which one element exhibits the properties of both an oxide and a reducing agent. With disproportionation, compounds are simultaneously formed in which the element is in a more oxidized and reduced state compared to the primitive one. The oxidation state of the Chlorine atom in the hypochlorite acid molecule is +1:
The interaction of chlorine with alkali solutions proceeds similarly. In this case, two salts are formed: chloride and hypochlorite.
Chlorine interacts with various oxides:
Chlorine oxidizes some salts in which the metal is not in the maximum oxidation state:
Molecular chlorine reacts with many organic compounds. In the presence of ferrum(III) chloride as a catalyst, chlorine reacts with benzene to form chlorobenzene, and when irradiated with light, the same reaction produces hexachlorocyclohexane:
Chemical properties bromine and iodine
Both substances react with hydrogen, fluorine and alkalis:
Iodine is oxidized by various strong oxidizing agents:
Methods for the extraction of simple substances
Extraction of fluorine
Since fluorine is the strongest chemical oxide, it is impossible to isolate it by chemical reactions from compounds in a free form, and therefore fluorine is mined by the physicochemical method - electrolysis.
To extract fluorine, potassium fluoride melt and nickel electrodes are used. Nickel is used due to the fact that the surface of the metal is passivated by fluorine due to the formation of insoluble
NiF2, therefore, the electrodes themselves are not destroyed by the action of the substance that is released on them:Extraction of chlorine
Chlorine is commercially produced by electrolysis of sodium chloride solution. As a result of this process, sodium hydroxide is also extracted:
In small quantities, chlorine is obtained by oxidizing a solution of hydrogen chloride by various methods:
Chlorine is a very important product of the chemical industry.
Its world production is millions of tons.
Extraction of bromine and iodine
For industrial use, bromine and iodine are obtained from the oxidation of bromides and iodides, respectively. For oxidation, molecular chlorine, concentrated sulfate acid or manganese dioxide are most often used:
Fluorine and some of its compounds are used as an oxidizing agent for rocket fuel. Large amounts of fluorine are used to produce various refrigerants (freons) and some polymers that are characterized by chemical and thermal resistance (Teflon and some others). Fluorine is used in nuclear technology to separate uranium isotopes.
Most of the chlorine is used to produce hydrochloric acid, and also as an oxidizing agent for the extraction of other halogens. In industry, it is used to bleach fabrics and paper. In larger quantities than fluorine, it is used for the production of polymers (PVC and others) and refrigerants. Chlorine is used to disinfect drinking water. It is also needed to extract some solvents such as chloroform, methylene chloride, carbon tetrachloride. And it is also used to produce many substances, such as potassium chlorate (bertolet salt), bleach and many other compounds containing chlorine atoms.
Bromine and iodine are not used in industry on the same scale as chlorine or fluorine, but the use of these substances is increasing every year. Bromine is used in the manufacture of various sedative medicines. Iodine is used in the manufacture of antiseptic preparations. Bromine and iodine compounds are widely used in quantitative analysis substances. With the help of iodine, some metals are purified (this process is called iodine refining), such as titanium, vanadium and others.
The work selected tasks on chemical bonds.
Pugacheva Elena Vladimirovna
Development description
6. A covalent non-polar bond is characteristic of
1) Cl 2 2) SO3 3) CO 4) SiO 2
1) NH 3 2) Cu 3) H 2 S 4) I 2
3) ionic 4) metallic
15. Three common electron pairs form a covalent bond in a molecule
16. Hydrogen bonds are formed between molecules
1) HI 2) HCl 3) HF 4) HBr
1) water and diamond 2) hydrogen and chlorine 3) copper and nitrogen 4) bromine and methane
19. Hydrogen bond not typical for substance
1) fluorine 2) chlorine 3) bromine 4) iodine
1) CF 4 2) CCl 4 3) CBr 4 4) CI 4
1) 1 2) 2 3) 3 4) 4
1) 1 2) 2 3) 3 4) 4
32. Atoms of chemical elements of the second period of the periodic system D.I. Mendeleev form compounds with an ionic chemical bond of composition 1) LiF 2) CO 2 3) Al 2 O 3 4) BaS
1) ionic 2) metallic
43. An ionic bond is formed by 1) H and S 2) P and C1 3) Cs and Br 4) Si and F
when interacting
1) ionic 2) metallic
1) ionic 2) metallic
NAME OF THE SUBSTANCE TYPE OF COMMUNICATION
1) zinc A) ionic
2) nitrogen B) metal
62. Match
TYPE OF COMMUNICATION CONNECTION
1) ionic A) H 2
2) metal B) Va
3) covalent polar B) HF
66. The strongest chemical bond takes place in the molecule 1) F 2 2) Cl 2 3) O 2 4) N 2
67. Bond strength increases in the series 1) Cl 2 -O 2 -N 2 2) O 2 - N 2- Cl 2 3) O 2 -Cl 2 -N 2 4) Cl 2 -N 2 -O 2
68. Indicate a series characterized by an increase in the length of a chemical bond
1) O 2, N 2, F 2, Cl 2 2) N 2, O 2, F 2, Cl 2 3) F 2, N 2, O 2, Cl 2 4) N 2, O 2, Cl 2, F2
Let's analyze tasks number 3 from USE options for 2016.
Tasks with solutions.
Task number 1.
Compounds with a covalent non-polar bond are located in the series:
1. O2, Cl2, H2
2. HCl, N2, F2
3. O3, P4, H2O
4.NH3, S8, NaF
Explanation: we need to find such a series in which there will be only simple substances, since a covalent non-polar bond is formed only between atoms of the same element. The correct answer is 1.
Task number 2.
Substances with a covalent polar bond are listed in the series:
1. CaF2, Na2S, N2
2. P4, FeCl2, NH3
3. SiF4, HF, H2S
4. NaCl, Li2O, SO2
Explanation: here you need to find a series in which only complex substances and, moreover, all non-metals. The correct answer is 3.
Task number 3.
The hydrogen bond is characteristic of
1. Alkanes 2. Arenes 3. Alcohols 4. Alkynes
Explanation: A hydrogen bond is formed between a hydrogen ion and an electronegative ion. Such a set, among those listed, is only for alcohols.
The correct answer is 3.
Task number 4.
Chemical bond between water molecules
1. Hydrogen
2. Ionic
3. Covalent polar
4. Covalent non-polar
Explanation: a covalent polar bond is formed between the O and H atoms in water, since these are two non-metals, but a hydrogen bond is formed between water molecules. The correct answer is 1.
Task number 5.
Only covalent bonds have each of the two substances:
1. CaO and C3H6
2. NaNO3 and CO
3. N2 and K2S
4.CH4 and SiO2
Explanation: compounds must consist only of non-metals, i.e. the correct answer is 4.
Task number 6.
A substance with a covalent polar bond is
1. O3 2. NaBr 3. NH3 4. MgCl2
Explanation: A polar covalent bond is formed between atoms of different non-metals. The correct answer is 3.
Task number 7.
A non-polar covalent bond is characteristic of each of the two substances:
1. Water and diamond
2. Hydrogen and chlorine
3. Copper and nitrogen
4. Bromine and methane
Explanation: a non-polar covalent bond is characteristic of the connection of atoms of the same non-metal element. The correct answer is 2.
Task number 8.
What chemical bond is formed between atoms of elements with serial numbers 9 and 19?
1. Ionic
2. Metal
3. Covalent polar
4. Covalent non-polar
Explanation: these are elements - fluorine and potassium, that is, a non-metal and a metal, respectively, only an ionic bond can form between such elements. The correct answer is 1.
Task number 9.
A substance with an ionic bond type corresponds to the formula
1. NH3 2. HBr 3. CCl4 4. KCl
Explanation: an ionic bond is formed between a metal atom and a nonmetal atom, that is the correct answer is 4.
Task number 10.
The same type of chemical bond have hydrogen chloride and
1. Ammonia
2. Bromine
3. Sodium chloride
4. Magnesium oxide
Explanation: Hydrogen chloride has a covalent polar bond, that is, we need to find a substance consisting of two different non-metals - this is ammonia.
The correct answer is 1.
Tasks for independent decision.
1. Hydrogen bonds form between molecules
1. Hydrofluoric acid
2. Chloromethane
3. Dimethyl ether
4. Ethylene
2. A compound with a covalent bond corresponds to the formula
1. Na2O 2. MgCl2 3. CaBr2 4. HF
3. A substance with a covalent non-polar bond has the formula
1. H2O 2. Br2 3. CH4 4. N2O5
4. A substance with an ionic bond is
1. CaF2 2. Cl2 3. NH3 4. SO2
5. Hydrogen bonds form between molecules
1. Methanol
3. Acetylene
4. Methyl formate
6. A covalent non-polar bond is characteristic of each of the two substances:
1. Nitrogen and ozone
2. Water and ammonia
3. Copper and nitrogen
4. Bromine and methane
7. A covalent polar bond is characteristic of a substance
1. KI 2. CaO 3. Na2S 4. CH4
8. A covalent non-polar bond is characteristic of
1. I2 2. NO 3. CO 4. SiO2
9. A substance with a covalent polar bond is
1. Cl2 2. NaBr 3. H2S 4. MgCl2
10. A covalent non-polar bond is characteristic of each of the two substances:
1. Hydrogen and chlorine
2. Water and diamond
3. Copper and nitrogen
4. Bromine and methane
This note used assignments from the USE collection of 2016, edited by A.A. Kaverina.
A4 Chemical bond.
Chemical bond: covalent (polar and non-polar), ionic, metallic, hydrogen. Methods for the formation of a covalent bond. Characteristics of a covalent bond: bond length and energy. Formation of an ionic bond.
Option 1 - 1,5,9,13,17,21,25,29,33,37,41,45,49,53,57,61,65
Option 2 - 2,6,10,14,18,22,26,30,34,38,42,46,50,54,58,62,66
Option 3 - 3,7,11,15,19,23,27,31,35,39,43,47,51,55,59,63,67
Option 4 - 4,8,12,16,20,24,28,32,36,40,44,48,52,56,60,64,68
1. In ammonia and barium chloride, the chemical bond, respectively
1) ionic and covalent polar
2) covalent polar and ionic
3) covalent non-polar and metallic
4) covalent non-polar and ionic
2. Substances with only ionic bonds are listed in the series:
1) F 2, CCl 4, KCl 2) NaBr, Na 2 O, KI 3) SO 2 .P 4 .CaF 2 4) H 2 S, Br 2 , K 2 S
3. A compound with an ionic bond is formed by interaction
1) CH 4 and O 2 2) SO 3 and H 2 O 3) C 2 H 6 and HNO 3 4) NH 3 and HCI
4. In what series do all substances have a covalent polar bond?
1) HCl, NaCl, Cl 2 2) O 2, H 2 O, CO 2 3) H 2 O, NH 3, CH 4 4) NaBr, HBr, CO
5. In which row are the formulas of substances written only with a covalent polar bond?
1) Cl 2, NO 2, HCl 2) HBr, NO, Br 2 3) H 2 S, H 2 O, Se 4) HI, H 2 O, PH 3
6. A covalent non-polar bond is characteristic of
1) Cl 2 2) SO3 3) CO 4) SiO 2
7. A substance with a covalent polar bond is
1) C1 2 2) NaBr 3) H 2 S 4) MgCl 2
8. A substance with a covalent bond is
1) CaCl 2 2) MgS 3) H 2 S 4) NaBr
9. A substance with a covalent non-polar bond has the formula
1) NH 3 2) Cu 3) H 2 S 4) I 2
10. Substances with a non-polar covalent bond are
11. A chemical bond is formed between atoms with the same electronegativity
1) ionic 2) covalent polar 3) covalent non-polar 4) hydrogen
12. A covalent polar bond is characteristic of
1) KCl 2) HBr 3) P 4 4) CaCl 2
13. A chemical element in the atom of which the electrons are distributed over the layers as follows: 2, 8, 8, 2 forms a chemical bond with hydrogen
1) covalent polar 2) covalent non-polar
3) ionic 4) metallic
14. In a molecule of what substance is the bond length between carbon atoms the longest?
1) acetylene 2) ethane 3) ethene 4) benzene
15. Three common electron pairs form a covalent bond in a molecule
1) nitrogen 2) hydrogen sulfide 3) methane 4) chlorine
16. Hydrogen bonds are formed between molecules
1) dimethyl ether 2) methanol 3) ethylene 4) ethyl acetate
17. The polarity of the bond is most pronounced in the molecule
1) HI 2) HCl 3) HF 4) HBr
18. Substances with a non-polar covalent bond are
1) water and diamond 2) hydrogen and chlorine 3) copper and nitrogen 4) bromine and methane
19. Hydrogen bond not typical for substance
1) H 2 O 2) CH 4 3) NH 3 4) CH3OH
20. A covalent polar bond is characteristic of each of the two substances, the formulas of which
1) KI and H 2 O 2) CO 2 and K 2 O 3) H 2 S and Na 2 S 4) CS 2 and PC1 5
21. The least strong chemical bond in a molecule
22. In the molecule of which substance is the length of the chemical bond the longest?
1) fluorine 2) chlorine 3) bromine 4) iodine
23. Each of the substances indicated in the series has covalent bonds:
1) C 4 H 10, NO 2, NaCl 2) CO, CuO, CH 3 Cl 3) BaS, C 6 H 6, H 2 4) C 6 H 5 NO 2, F 2, CCl 4
24. Each of the substances indicated in the series has a covalent bond:
1) CaO, C 3 H 6, S 8 2) Fe, NaNO 3, CO 3) N 2, CuCO 3, K 2 S 4) C 6 H 5 N0 2, SO 2, CHC1 3
25. Each of the substances indicated in the series has a covalent bond:
1) C 3 H 4, NO, Na 2 O 2) CO, CH 3 C1, PBr 3 3) P 2 Oz, NaHSO 4, Cu 4) C 6 H 5 NO 2, NaF, CCl 4
26. Each of the substances indicated in the series has covalent bonds:
1) C 3 H a, NO 2, NaF 2) KCl, CH 3 Cl, C 6 H 12 0 6 3) P 2 O 5, NaHSO 4, Ba 4) C 2 H 5 NH 2, P 4, CH 3 Oh
27. Bond polarity is most pronounced in molecules
1) hydrogen sulfide 2) chlorine 3) phosphine 4) hydrogen chloride
28. In the molecule of what substance are chemical bonds the strongest?
1) CF 4 2) CCl 4 3) CBr 4 4) CI 4
29. Among the substances NH 4 Cl, CsCl, NaNO 3, PH 3, HNO 3 - the number of compounds with an ionic bond is
1) 1 2) 2 3) 3 4) 4
30. Among the substances (NH 4) 2 SO 4, Na 2 SO 4, CaI 2, I 2, CO 2 - the number of compounds with a covalent bond is
1) 1 2) 2 3) 3 4) 4
31. In substances formed by combining identical atoms, a chemical bond
1) ionic 2) covalent polar 3) hydrogen 4) covalent non-polar
32. Atoms of chemical elements of the second period of the periodic system D.I. Mendeleev form compounds with an ionic chemical bond of composition 1) LiF 2) CO 2 3) Al 2 O 3 4) BaS
33. Compounds with covalent polar and covalent non-polar bonds are respectively 1) water and hydrogen sulfide 2) potassium bromide and nitrogen 3) ammonia and hydrogen 4) oxygen and methane
34. A covalent non-polar bond is characteristic of 1) water 2) ammonia 3) nitrogen 4) methane
35. Chemical bond in a hydrogen fluoride molecule
1) covalent polar 3) ionic
2) covalent non-polar 4) hydrogen
36. Choose a pair of substances, all bonds in which are covalent:
1) NaCl, Hcl 2) CO 2, BaO 3) CH 3 Cl, CH 3 Na 4) SO 2, NO 2
37. In potassium iodide, a chemical bond
1) covalent non-polar 3) metallic
2) covalent polar 4) ionic
38. In carbon disulfide CS 2 chemical bond
1) ionic 2) metallic
3) covalent polar 4) covalent non-polar
39. A covalent non-polar bond is realized in a compound
1) CrO 3 2) P 2 O 5 3) SO 2 4) F 2
40. A substance with a covalent polar bond has the formula 1) KCl 2) HBr 3) P 4 4) CaCl 2
41. Connection with the ionic nature of the chemical bond
1) phosphorus chloride 2) potassium bromide 3) nitric oxide (II) 4) barium
42. In ammonia and barium chloride, the chemical bond, respectively
1) ionic and covalent polar 2) covalent polar and ionic
3) covalent non-polar and metallic 4) covalent non-polar and ionic
43. An ionic bond is formed by 1) H and S 2) P and C1 3) Cs and Br 4) Si and F
44. What type of bond is in the H 2 molecule?
1) Ionic 2) Hydrogen 3) Covalent non-polar 4) Donor-acceptor
45. A substance with a covalent polar bond is
1) sulfur oxide (IV) 2) oxygen 3) calcium hydride 4) diamond
46. In a fluorine molecule, a chemical bond
1) covalent polar 2) ionic 3) covalent non-polar 4) hydrogen
47. In which series are substances listed only with a covalent polar bond:
1) CH 4 H 2 Cl 2 2) NH 3 HBr CO 2 3) PCl 3 KCl CCl 4 4) H 2 S SO 2 LiF
48. In what series do all substances have a covalent polar bond?
1) Hcl, NaCl, Cl 2 2) O 2 H 2 O, CO 2 3) H 2 O, NH 3, CH 4 4) KBr, HBr, CO
49. In which row are listed substances only with an ionic type of bond:
1) F 2 O LiF SF 4 2) PCl 3 NaCl CO 2 3) KF Li 2 O BaCl 2 4) CaF 2 CH 4 CCl 4
50. A compound with an ionic bond is formed when interacting
1) CH 4 and O 2 2) NH 3 and HCl 3) C 2 H 6 and HNO 3 4) SO 3 and H 2 O
51. A hydrogen bond is formed between the molecules of 1) ethane 2) benzene 3) hydrogen 4) ethanol
52. What substance has hydrogen bonds? 1) Hydrogen sulfide 2) Ice 3) Hydrogen bromide 4) Benzene
53. Relationship formed between elements with serial numbers 15 and 53
1) ionic 2) metallic
3) covalent non-polar 4) covalent polar
54. Relationship formed between elements with serial numbers 16 and 20
1) ionic 2) metallic
3) covalent polar 4) hydrogen
55. A bond arises between the atoms of elements with serial numbers 11 and 17
1) metallic 2) ionic 3) covalent 4) donor-acceptor
56. Hydrogen bonds are formed between molecules
1) hydrogen 2) formaldehyde 3) acetic acid 4) hydrogen sulfide
57. In which row are the formulas of substances written only with a covalent polar bond?
1) Cl 2, NH 3, HCl 2) HBr, NO, Br 2 3) H 2 S, H 2 O, S 8 4) NI, H 2 O, PH 3
58. In what substance are there both ionic and covalent chemical bonds?
1) Sodium chloride 2) Hydrogen chloride 3) Sodium sulfate 4) Phosphoric acid
59. A chemical bond in a molecule has a more pronounced ionic character.
1) lithium bromide 2) copper chloride 3) calcium carbide 4) potassium fluoride
60. In what substance are all chemical bonds - covalent non-polar?
1) Diamond 2) Carbon monoxide (IV) 3) Gold 4) Methane
61. Establish a correspondence between the substance and the type of bond of atoms in this substance.
NAME OF THE SUBSTANCE TYPE OF COMMUNICATION
1) zinc A) ionic
2) nitrogen B) metal
3) ammonia B) covalent polar
4) calcium chloride D) covalent non-polar
62. Match
TYPE OF COMMUNICATION CONNECTION
1) ionic A) H 2
2) metal B) Va
3) covalent polar B) HF
4) covalent non-polar D) BaF 2
63. In what compound is the covalent bond between atoms formed by the donor-acceptor mechanism? 1) KCl 2) CCl 4 3) NH 4 Cl 4) CaCl 2
64. Indicate the molecule in which the binding energy is the highest: 1) N≡N 2) H-H 3) O=O 4) H-F
65. Indicate the molecule in which the chemical bond is the strongest: 1) HF 2) HCl 3) HBr 4) HI
(first electron)
(according to Pauling)
| F | 9 |
| 18,9984 | |
| 2s 2 2p 5 | |
| Fluorine | |
Chemical properties
The most active non-metal, it violently interacts with almost all substances (rare exceptions are fluoroplasts), and with most of them - with combustion and explosion. The contact of fluorine with hydrogen leads to ignition and explosion even at very low temperatures (up to −252°C). Even water and platinum: uranium for the nuclear industry burn in a fluorine atmosphere.
chlorine trifluoride ClF 3 - a fluorinating agent and a powerful rocket fuel oxidizer
sulfur hexafluoride SF 6 - gaseous insulator in the electrical industry
metal fluorides (for example, W and V), which have some useful properties
freons are good refrigerants
teflon - chemically inert polymers
sodium hexafluoroaluminate - for the subsequent production of aluminum by electrolysis
various fluorine compounds
Missile technology
Fluorine compounds are widely used in rocket technology as a propellant oxidizer.Application in medicine
Fluorine compounds are widely used in medicine as blood substitutes.
Biological and physiological role
Fluorine is a vital element for the body. In the human body, fluorine is mainly found in tooth enamel as part of fluorapatite - Ca 5 F (PO 4) 3 . With insufficient (less than 0.5 mg / liter of drinking water) or excessive (more than 1 mg / liter) fluoride intake by the body, dental diseases can develop: caries and fluorosis (mottled enamel) and osteosarcoma, respectively.
To prevent caries, it is recommended to use toothpastes with fluoride additives or drink fluoridated water (up to a concentration of 1 mg / l), or apply local applications with a 1-2% solution of sodium fluoride or stannous fluoride. Such actions can reduce the likelihood of caries by 30-50%.
Maximum allowable concentration of bound fluorine in air industrial premises equal to 0.0005 mg/liter.
Additional Information
Fluorine, Fluorum, F(9)
Fluorine (Fluorine, French and German Fluor) was obtained in a free state in 1886, but its compounds have been known for a long time and were widely used in metallurgy and glass production. The first mention of fluorite (CaP,) under the name fluorspar (Fliisspat) dates back to the 16th century. One of the works attributed to the legendary Vasily Valentin mentions stones painted in various colors - fluxes (Fliisse from Latin fluere - flow, pour), which were used as fluxes in the smelting of metals. Agricola and Libavius write about the same. The latter introduces special names for this flux - fluorspar (Flusspat) and mineral melt. Many authors of chemical and technical writings of the 17th and 18th centuries. describe different types fluorspar. In Russia, these stones were called plavik, spalt, spat; Lomonosov classified these stones as selenites and called them spar or flux (crystal flux). Russian masters, as well as collectors of mineral collections (for example, in the 18th century, Prince P.F. Golitsyn) knew that some types of spars when heated (for example, in hot water) glow in the dark. However, even Leibniz in his history of phosphorus (1710) mentions in this connection thermophosphorus (Thermophosphorus).
Apparently, chemists and artisan chemists became acquainted with hydrofluoric acid no later than the 17th century. In 1670, the Nuremberg craftsman Schwanhard used fluorspar mixed with sulfuric acid to etch designs on glass goblets. However, at that time the nature of fluorspar and hydrofluoric acid was completely unknown. It was believed, for example, that silicic acid has an etching effect in the Schwanhard process. This erroneous opinion was eliminated by Scheele, proving that when fluorspar interacts with sulfuric acid, silicic acid is obtained as a result of the erosion of the glass retort by the resulting hydrofluoric acid. In addition, Scheele established (1771) that fluorspar is a combination of calcareous earth with a special acid, which was called "Swedish acid".
Lavoisier recognized the hydrofluoric acid radical (radical fluorique) as a simple body and included it in his table of simple bodies. In more or less pure form hydrofluoric acid was obtained in 1809. Gay-Lussac and Tenard by distilling fluorspar with sulfuric acid in a lead or silver retort. During this operation, both researchers were poisoned. The true nature of hydrofluoric acid was established in 1810 by Ampère. He rejected Lavoisier's opinion that hydrofluoric acid must contain oxygen, and proved the analogy of this acid with hydrochloric acid. Ampère reported his findings to Davy, who shortly before that had established the elemental nature of chlorine. Davy fully agreed with Ampere's arguments and spent a lot of effort on obtaining free fluorine by electrolysis of hydrofluoric acid and in other ways. Taking into account the strong corrosive effect of hydrofluoric acid on glass, as well as on plant and animal tissues, Ampere suggested calling the element contained in it fluorine (Greek - destruction, death, pestilence, plague, etc.). However, Davy did not accept this name and proposed another - fluorine (Fluorine) by analogy with the then name of chlorine - chlorine (Chlorine), both names are still used in English language. In Russian, the name given by Ampere has been preserved.
Numerous attempts to isolate free fluorine in the 19th century did not lead to successful results. Only in 1886 did Moissan manage to do this and obtain free fluorine in the form of a yellow-green gas. Since fluorine is an unusually aggressive gas, Moissan had to overcome many difficulties before he found a material suitable for the apparatus in experiments with fluorine. The U-tube for electrolysis of hydrofluoric acid at 55°C (cooled with liquid methyl chloride) was made of platinum with fluorspar plugs. After the chemical and physical properties of free fluorine were investigated, it found wide application. Now fluorine is one of the critical components synthesis of fluoroorganic substances of a wide range. In Russian literature early XIX in. fluorine was called differently: the base of hydrofluoric acid, fluorine (Dvigubsky, 1824), fluorine (Iovsky), fluor (Shcheglov, 1830), fluor, fluorine, fluorine. Hess from 1831 introduced the name fluorine.
Atom, molecule, nuclear properties
The structure of the fluorine atom.
At the center of an atom is a positively charged nucleus. 9 negatively charged electrons revolve around.
Electronic formula: 1s2;2s2;2p5
m prot. = 1.00783 (a.m.u.)
m neutral = 1.00866 (a.m.u.)
m proton = m electron
Isotopes of fluorine.
Isotope: 18F
a brief description of: Prevalence in nature: 0%
The number of protons in the nucleus is 9. The number of neutrons in the nucleus is 9. The number of nucleons is 18.E bonds \u003d 931.5 (9 * m pr. + 9 * m neutron-M (F18)) \u003d 138.24 (MEV) E specific = E bonds/N nucleons = 7.81 (MEV/nucleon)
Alpha decay is impossibleBeta minus decay is impossiblePositron decay: F(Z=9,M=18)-->O(Z=8,M=18)+e(Z=+1,M=0)+0.28( MeV) Electronic capture: F(Z=9,M=18)+e(Z=-1,M=0)-->O(Z=8,M=18)+1.21(MeV)
Isotope: 19F
Brief description: Prevalence in nature: 100%
fluorine molecule.
Free fluorine consists of diatomic molecules. From the chemical point of view, fluorine can be characterized as a monovalent non-metal, and, moreover, the most active of all non-metals. This is due to a number of reasons, including the ease of decomposition of the F2 molecule into individual atoms - the energy required for this is only 159 kJ / mol (against 493 kJ / mol for O2 and 242 kJ / mol for C12). Fluorine atoms have a significant electron affinity and are relatively small in size. Therefore, their valence bonds with atoms of other elements are stronger than similar bonds of other metalloids (for example, the energy H-F bonds is - 564 kJ/mol versus 460 kJ/mol for N-O connections and 431 kJ/mol for the H-C1 bond).
F-F connection characterized by a nuclear distance of 1.42 A. For the thermal dissociation of fluorine, the following data were obtained by calculation:
Temperature, °С 300 500 700 900 1100 1300 1500 1700
Degree of dissociation, % 5 10-3 0.3 4.2 22 60 88 97 99
The fluorine atom in the ground state has the structure of the outer electron layer 2s22p5 and is monovalent. The excitation of the trivalent state associated with the transfer of one 2p electron to the 3s level requires an expenditure of 1225 kJ/mol and is practically not realized. The electron affinity of a neutral fluorine atom is estimated at 339 kJ/mol. The F- ion is characterized by an effective radius of 1.33 A and a hydration energy of 485 kJ/mol. The covalent radius of fluorine is usually taken to be 71 pm (i.e., half the internuclear distance in the F2 molecule).
Chemical properties of fluorine.
Since fluorine derivatives of metalloid elements are usually highly volatile, their formation does not protect the surface of the metalloid from further action of fluorine. Therefore, the interaction often proceeds much more vigorously than with many metals. For example, silicon, phosphorus and sulfur ignite in fluorine gas. Amorphous carbon (charcoal) behaves similarly, while graphite reacts only at a red heat temperature. Fluorine does not combine directly with nitrogen and oxygen.
From the hydrogen compounds of other elements, fluorine takes away hydrogen. Most oxides are decomposed by it with the displacement of oxygen. In particular, water interacts according to the scheme F2 + H2O --> 2 HF + O
moreover, the displaced oxygen atoms combine not only with each other, but also partially with water and fluorine molecules. Therefore, in addition to gaseous oxygen, this reaction always produces hydrogen peroxide and fluorine oxide (F2O). The latter is a pale yellow gas, similar in smell to ozone.
Fluorine oxide (otherwise - oxygen fluoride - OF2) can be obtained by passing fluorine in 0.5 N. NaOH solution. The reaction proceeds according to the equation: 2 F2 + 2 NaOH = 2 NaF + H2O + F2OT The following reactions are also characteristic of fluorine:
H2 + F2 = 2HF (with explosion)
